Re: Does allocating an HFS or zFS erase all existing data?intervals formatted?
Because Wikipedia would not consider that a reliable source. What I need is a published document that I can cite to justify the challenged footnote " 1 Not true for CMS file system[2] on a CMS minidisk, TSS VAM-formatted volume,[3] z/OS Unix file systems[citation needed] or VSAM in IBM mainframes " to "As a general rule,[nb 1] formatting a disk by default leaves most if not all existing data on the disk medium; some or most of which might be recoverable with privileged[nb 2] or special tools.[4]" -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of Mark Jacobs [0224d287a4b1-dmarc-requ...@listserv.ua.edu] Sent: Tuesday, May 19, 2020 10:08 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Does allocating an HFS or zFS erase all existing data?intervals formatted? Unless I'm totally off the mark here, why not go through this process (or something like it) and see for yourself. 1) Use an empty 3390 volume. 2) Allocate a single PS dataset that takes up the entire volume. 3) Use IEBDG to write a known value to each block in the dataset. 4) Delete the dataset. 5) Allocate HSF and zFS datasets on the volume. 6) DFDSS (or other tool) to print the track contents in the allocated space. 7) Review output. Mark Jacobs Sent from ProtonMail, Swiss-based encrypted email. GPG Public Key - https://secure-web.cisco.com/1gFYwIxkr1KZghOPP0bmd9UCZ3A32F6aKyRlie071QEp6B8F4K5623W_ZThHbxX_9XjtAI51EmQ9VqQf6ftGgqa8RHkNUgQkupA2dcNYGPCDt6hjTWtXQmUgUhtrSHHZlbJlpusSRr-cqz27SDoB0auiltqFr6X0jamxG0gDa9X4vnUbwfQRrN6ZBsFsclp6TI8zlzKOCxB4jcXLIHe8sPvcS0QuUExDXarvaWIMKe46mi7YeFieyHxf_FaQL2FUshplNXeIwn-QQ6Tgt40GL3JTb9DGoVje-22LgV5w783cp7btfgseip0nl64JQdpJpKzZFs2RHMTAXLxouRfAahorTrMcGBxcZOG0gMEgbSf_8xgeOzCYJrDzc3VUIz3WRguaRh0vgG5kO5f2EK9iU-ZqFeQEK8_K8tIBrKpf0SBlIGosd0whdiKKOoUETBlSB/https%3A%2F%2Fapi.protonmail.ch%2Fpks%2Flookup%3Fop%3Dget%26search%3Dmarkjacobs%40protonmail.com ‐‐‐ Original Message ‐‐‐ On Tuesday, May 19, 2020 9:30 AM, Seymour J Metz wrote: > There is, or used to be, a common service used by VSAM and other components > for data with CI-like formatting, including PDSE. If it still exists then I > assume that it is also used for HFS. My prime concern was HFS and zFS, and I > don't know whether SPEED/RECOVERY applies to linear, which zFS is based on. > > > -- > > Shmuel (Seymour J.) Metz > http://mason.gmu.edu/~smetz3 > > From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of > Mike Kerford-Byrnes [m...@hill-leys.com] > Sent: Tuesday, May 19, 2020 8:11 AM > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: Re: Does allocating an HFS or zFS erase all existing data?intervals > formatted? > > From various manuals - and a lot of time spent with VSAM... > > A VSAM file is DEFINEd with an amount of space. This space is managed by > VSAM as a set of Control Areas (CAs). The maximum size of a CA is 1 > Cylinder, and the minimum is one track. > > Each CA contains a number of Control Intervals (CIs), of fixed length, > determined at DEFINE time. The last 4 bytes of a CI (the CIDF) contain > information as to the occupancy of the CI (amount of unused space and its > offset). A CIDF containing all zeros is known as a Software End Of File or > SEOF. The CIDF of an EMPTY CI shows (CISIZ - 4) bytes available at offset > 0. > > Records are stored in the CI (left to right) along with control information > (3-byte 'RDF' stored right to left). > > Linear Datasets are different. They do not have any control information in > the (mandatory) 4K CIs which are employed to store the data. As far as I > can deduce, the only connection to VSAM is that it provides the vehicle to > read and write 4K blocks of data to and from a disk and a catalog structure > in which to hold relevant data about the file - name, size, volser etc. > Although I have used a linear Dataset in the past (1994!) I have not > researched it in any detail. > > When a file is DEFINEd, nothing happens to the tracks. Only when the file > is loaded does anything happen. > > What happens depends on the choice of SPEED/RECOVERY at DEFINE time and the > type of VSAM file. > > SPEED > > When SPEED is specified, records are loaded into each control interval, > along with the RDF, and the CIDF is updated as each record is loaded. This > continues across all relevant CIs until the load is complete. At CLOSE (and
Re: Does allocating an HFS or zFS erase all existing data?intervals formatted?
Unless I'm totally off the mark here, why not go through this process (or something like it) and see for yourself. 1) Use an empty 3390 volume. 2) Allocate a single PS dataset that takes up the entire volume. 3) Use IEBDG to write a known value to each block in the dataset. 4) Delete the dataset. 5) Allocate HSF and zFS datasets on the volume. 6) DFDSS (or other tool) to print the track contents in the allocated space. 7) Review output. Mark Jacobs Sent from ProtonMail, Swiss-based encrypted email. GPG Public Key - https://api.protonmail.ch/pks/lookup?op=get&search=markjac...@protonmail.com ‐‐‐ Original Message ‐‐‐ On Tuesday, May 19, 2020 9:30 AM, Seymour J Metz wrote: > There is, or used to be, a common service used by VSAM and other components > for data with CI-like formatting, including PDSE. If it still exists then I > assume that it is also used for HFS. My prime concern was HFS and zFS, and I > don't know whether SPEED/RECOVERY applies to linear, which zFS is based on. > > > -- > > Shmuel (Seymour J.) Metz > http://mason.gmu.edu/~smetz3 > > From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of > Mike Kerford-Byrnes [m...@hill-leys.com] > Sent: Tuesday, May 19, 2020 8:11 AM > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: Re: Does allocating an HFS or zFS erase all existing data?intervals > formatted? > > From various manuals - and a lot of time spent with VSAM... > > A VSAM file is DEFINEd with an amount of space. This space is managed by > VSAM as a set of Control Areas (CAs). The maximum size of a CA is 1 > Cylinder, and the minimum is one track. > > Each CA contains a number of Control Intervals (CIs), of fixed length, > determined at DEFINE time. The last 4 bytes of a CI (the CIDF) contain > information as to the occupancy of the CI (amount of unused space and its > offset). A CIDF containing all zeros is known as a Software End Of File or > SEOF. The CIDF of an EMPTY CI shows (CISIZ - 4) bytes available at offset > 0. > > Records are stored in the CI (left to right) along with control information > (3-byte 'RDF' stored right to left). > > Linear Datasets are different. They do not have any control information in > the (mandatory) 4K CIs which are employed to store the data. As far as I > can deduce, the only connection to VSAM is that it provides the vehicle to > read and write 4K blocks of data to and from a disk and a catalog structure > in which to hold relevant data about the file - name, size, volser etc. > Although I have used a linear Dataset in the past (1994!) I have not > researched it in any detail. > > When a file is DEFINEd, nothing happens to the tracks. Only when the file > is loaded does anything happen. > > What happens depends on the choice of SPEED/RECOVERY at DEFINE time and the > type of VSAM file. > > SPEED > > When SPEED is specified, records are loaded into each control interval, > along with the RDF, and the CIDF is updated as each record is loaded. This > continues across all relevant CIs until the load is complete. At CLOSE (and > only then), the SEOF is written and the Catalog will show a value in the > High Used RBA field. > > For ESDS and RRDS, the SEOF is written in the CI FOLLOWING the last occupied > CI. All remaining CIs in the current CA are also formatted as EMPTY. > > For a KSDS, all remaining CIs in the CA are formatted as EMPTY, and the > first CI in the NEXT CA is also formatted as SEOF (assuming space is > available). The HURBA reflects the last byte in the CA that contains loaded > data. > > RECOVERY > > When RECOVERY is specified (or defaulted), each CA is preformatted > immediately prior to its load. > > For both ESDS and RRDS, each CI in the CA is formatted with SEOF. > > For a KSDS, All CIs in the CA are formatted as EMPTY and the first CI of the > NEXT CA is also formatted as a SEOF (again assuming space is available). > > In all cases, the load of that CA proceeds updating each CI in turn. > > CLOSE will update the HURBA as per SPEED. > > The net of this is that, in the case of RECOVERY, if the load fails part-way > through, there is a predictable format in the file structure such that a > 'resume load' can be executed (that is if you have programmed one to start > with!). There will always be a SEOF which identifies the last point at > which data was loaded. This is identified when a subsequent OPEN, having > detected a &#x
Re: Does allocating an HFS or zFS erase all existing data?intervals formatted?
There is, or used to be, a common service used by VSAM and other components for data with CI-like formatting, including PDSE. If it still exists then I assume that it is also used for HFS. My prime concern was HFS and zFS, and I don't know whether SPEED/RECOVERY applies to linear, which zFS is based on. -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of Mike Kerford-Byrnes [m...@hill-leys.com] Sent: Tuesday, May 19, 2020 8:11 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Does allocating an HFS or zFS erase all existing data?intervals formatted? >From various manuals - and a lot of time spent with VSAM... A VSAM file is DEFINEd with an amount of space. This space is managed by VSAM as a set of Control Areas (CAs). The maximum size of a CA is 1 Cylinder, and the minimum is one track. Each CA contains a number of Control Intervals (CIs), of fixed length, determined at DEFINE time. The last 4 bytes of a CI (the CIDF) contain information as to the occupancy of the CI (amount of unused space and its offset). A CIDF containing all zeros is known as a Software End Of File or SEOF. The CIDF of an EMPTY CI shows (CISIZ - 4) bytes available at offset 0. Records are stored in the CI (left to right) along with control information (3-byte 'RDF' stored right to left). Linear Datasets are different. They do not have any control information in the (mandatory) 4K CIs which are employed to store the data. As far as I can deduce, the only connection to VSAM is that it provides the vehicle to read and write 4K blocks of data to and from a disk and a catalog structure in which to hold relevant data about the file - name, size, volser etc. Although I have used a linear Dataset in the past (1994!) I have not researched it in any detail. When a file is DEFINEd, nothing happens to the tracks. Only when the file is loaded does anything happen. What happens depends on the choice of SPEED/RECOVERY at DEFINE time and the type of VSAM file. SPEED When SPEED is specified, records are loaded into each control interval, along with the RDF, and the CIDF is updated as each record is loaded. This continues across all relevant CIs until the load is complete. At CLOSE (and only then), the SEOF is written and the Catalog will show a value in the High Used RBA field. For ESDS and RRDS, the SEOF is written in the CI FOLLOWING the last occupied CI. All remaining CIs in the current CA are also formatted as EMPTY. For a KSDS, all remaining CIs in the CA are formatted as EMPTY, and the first CI in the NEXT CA is also formatted as SEOF (assuming space is available). The HURBA reflects the last byte in the CA that contains loaded data. RECOVERY When RECOVERY is specified (or defaulted), each CA is preformatted immediately prior to its load. For both ESDS and RRDS, each CI in the CA is formatted with SEOF. For a KSDS, All CIs in the CA are formatted as EMPTY and the first CI of the NEXT CA is also formatted as a SEOF (again assuming space is available). In all cases, the load of that CA proceeds updating each CI in turn. CLOSE will update the HURBA as per SPEED. The net of this is that, in the case of RECOVERY, if the load fails part-way through, there is a predictable format in the file structure such that a 'resume load' can be executed (that is if you have programmed one to start with!). There will always be a SEOF which identifies the last point at which data was loaded. This is identified when a subsequent OPEN, having detected a 'failed CLOSE', invokes the VERIFY function, which locates the SEOF, updates the catalog and then resumes the OPEN process with a 'clean' catalog. In the case of SPEED, there is no such support and you have to go back to the beginning and rerun. Although RECOVERY is the default, IBM recommend SPEED, since it is obviously a faster option. There is one 'gotcha' in this story. Once a file has been loaded (I.e. at least one record written, followed by a successful CLOSE), RECOVERY is operative, irrespective of the SPEED/RECOVERY option chosen at DEFINE time. So don't do what I have seen a couple of times - Open, load 1 control record, Close, followed by Open, load thousands of records, Close - under the misconception that SPEED is in effect throughout. Mike Kerford-Byrnes -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Does allocating an HFS or zFS erase all existing data?intervals formatted?
>From various manuals - and a lot of time spent with VSAM... A VSAM file is DEFINEd with an amount of space. This space is managed by VSAM as a set of Control Areas (CAs). The maximum size of a CA is 1 Cylinder, and the minimum is one track. Each CA contains a number of Control Intervals (CIs), of fixed length, determined at DEFINE time. The last 4 bytes of a CI (the CIDF) contain information as to the occupancy of the CI (amount of unused space and its offset). A CIDF containing all zeros is known as a Software End Of File or SEOF. The CIDF of an EMPTY CI shows (CISIZ - 4) bytes available at offset 0. Records are stored in the CI (left to right) along with control information (3-byte 'RDF' stored right to left). Linear Datasets are different. They do not have any control information in the (mandatory) 4K CIs which are employed to store the data. As far as I can deduce, the only connection to VSAM is that it provides the vehicle to read and write 4K blocks of data to and from a disk and a catalog structure in which to hold relevant data about the file - name, size, volser etc. Although I have used a linear Dataset in the past (1994!) I have not researched it in any detail. When a file is DEFINEd, nothing happens to the tracks. Only when the file is loaded does anything happen. What happens depends on the choice of SPEED/RECOVERY at DEFINE time and the type of VSAM file. SPEED When SPEED is specified, records are loaded into each control interval, along with the RDF, and the CIDF is updated as each record is loaded. This continues across all relevant CIs until the load is complete. At CLOSE (and only then), the SEOF is written and the Catalog will show a value in the High Used RBA field. For ESDS and RRDS, the SEOF is written in the CI FOLLOWING the last occupied CI. All remaining CIs in the current CA are also formatted as EMPTY. For a KSDS, all remaining CIs in the CA are formatted as EMPTY, and the first CI in the NEXT CA is also formatted as SEOF (assuming space is available). The HURBA reflects the last byte in the CA that contains loaded data. RECOVERY When RECOVERY is specified (or defaulted), each CA is preformatted immediately prior to its load. For both ESDS and RRDS, each CI in the CA is formatted with SEOF. For a KSDS, All CIs in the CA are formatted as EMPTY and the first CI of the NEXT CA is also formatted as a SEOF (again assuming space is available). In all cases, the load of that CA proceeds updating each CI in turn. CLOSE will update the HURBA as per SPEED. The net of this is that, in the case of RECOVERY, if the load fails part-way through, there is a predictable format in the file structure such that a 'resume load' can be executed (that is if you have programmed one to start with!). There will always be a SEOF which identifies the last point at which data was loaded. This is identified when a subsequent OPEN, having detected a 'failed CLOSE', invokes the VERIFY function, which locates the SEOF, updates the catalog and then resumes the OPEN process with a 'clean' catalog. In the case of SPEED, there is no such support and you have to go back to the beginning and rerun. Although RECOVERY is the default, IBM recommend SPEED, since it is obviously a faster option. There is one 'gotcha' in this story. Once a file has been loaded (I.e. at least one record written, followed by a successful CLOSE), RECOVERY is operative, irrespective of the SPEED/RECOVERY option chosen at DEFINE time. So don't do what I have seen a couple of times - Open, load 1 control record, Close, followed by Open, load thousands of records, Close - under the misconception that SPEED is in effect throughout. Mike Kerford-Byrnes -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Does allocating an HFS or zFS erase all existing data?intervals formatted?
I don't believe this is true. I know that Db2 will only "pre-format" a subset of pages when it opens a newly created LDS, or adds a new extent, rather than pre-formatting the entire dataset/extent. Wayne Driscoll Rocket Software Note - All opinions are strictly my own. -Original Message- From: IBM Mainframe Discussion List On Behalf Of Mike Schwab Sent: Friday, May 15, 2020 12:15 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Does allocating an HFS or zFS erase all existing data?intervals formatted? EXTERNAL EMAIL All VSAM datasets including Linear are formatted when created. The disk space used is not allocated to any other datasets. Previous data left by deleted datasets is usually left in place (erase on delete is an option but not used frequently) but frequently overwritten in a short time so restoring a deleted data set is almost always impossible. On Fri, May 15, 2020 at 4:25 PM Seymour J Metz wrote: > > I want to edit the wiki article [[Disk formatting]] to clarify the > statement "s a general rule,[nb 1] formatting a disk erases most if > not all existing data on the disk medium". Normally I would consult > the logic manuals :-( > > When you allocate an HFS or linear data set, does AMS preformat all of the > tracks? When you format a zFS, does that force formatting of all tracks? Can > you provide references that I can cite for the answers? > > Thanks. > > > > -- > Shmuel (Seymour J.) Metz > https://nam01.safelinks.protection.outlook.com/?url=http:%2F%2Fmason.g > mu.edu%2F~smetz3&data=02%7C01%7C%7C421a17b8a7be4aed45fb08d7f8f37cf > 4%7C79544c1eed224879a082b67a9a672aae%7C0%7C0%7C637251596968251708& > sdata=GI0Z4yvHlBuwKVQ3%2BJntG4HzfTreMlSIDJsPQ9PwjXE%3D&reserved=0 > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, send > email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN Rocket Software, Inc. and subsidiaries ■ 77 Fourth Avenue, Waltham MA 02451 ■ Main Office Toll Free Number: +1 855.577.4323 Contact Customer Support: https://my.rocketsoftware.com/RocketCommunity/RCEmailSupport Unsubscribe from Marketing Messages/Manage Your Subscription Preferences - http://www.rocketsoftware.com/manage-your-email-preferences Privacy Policy - http://www.rocketsoftware.com/company/legal/privacy-policy This communication and any attachments may contain confidential information of Rocket Software, Inc. All unauthorized use, disclosure or distribution is prohibited. If you are not the intended recipient, please notify Rocket Software immediately and destroy all copies of this communication. Thank you. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Does allocating an HFS or zFS erase all existing data?intervals formatted?
Easy to read, if you're authorized. -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of R.S. [r.skoru...@bremultibank.com.pl] Sent: Monday, May 18, 2020 9:03 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Does allocating an HFS or zFS erase all existing data?intervals formatted? Excuse me, but IMHO RECOVERY does "format" CIs within CA - that means proper values are written into CIDF and RDF (in any). That means VSAM knows the CI is empty, or partially filled. Unused space within CI is not cleared, there is no need for that. From the other hand physically full block is written. PB is usually equal CI (let's focus on this case), so everytime you write CIDF, you write full block. The rest of block may be zeros or just any value, but not previous content from the track. So - it seems the goal of RECOVERY is to write control fields, but the way its being done means whole CIs are rewritten. IMHO nevermind, because both SPEED and RECOVERY do not "format" all possible CI's within disk extent. So, even with RECOVERY it is possible to have residual data within the extent. Still hard to read, but not impossible. -- Radoslaw Skorupka Lodz, Poland W dniu 15.05.2020 o 21:17, Mike Schwab pisze: > https://www.ibm.com/support/knowledgecenter/SSLTBW_2.4.0/com.ibm.zos.v2r4.idai200/da6i2118.htm > Discussion on Speed / Recovery option. > > On Fri, May 15, 2020 at 5:34 PM Seymour J Metz wrote: >> Do you have something that I can cite for that, preferably something that >> all wiki readers can look at? >> >> >> -- >> Shmuel (Seymour J.) Metz >> http://mason.gmu.edu/~smetz3 >> >> >> From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of >> Mike Schwab [mike.a.sch...@gmail.com] >> Sent: Friday, May 15, 2020 1:14 PM >> To: IBM-MAIN@LISTSERV.UA.EDU >> Subject: Re: Does allocating an HFS or zFS erase all existing data?intervals >> formatted? >> >> All VSAM datasets including Linear are formatted when created. The >> disk space used is not allocated to any other datasets. Previous data >> left by deleted datasets is usually left in place (erase on delete is >> an option but not used frequently) but frequently overwritten in a >> short time so restoring a deleted data set is almost always >> impossible. >> >> On Fri, May 15, 2020 at 4:25 PM Seymour J Metz wrote: >>> I want to edit the wiki article [[Disk formatting]] to clarify the >>> statement "s a general rule,[nb 1] formatting a disk erases most if not all >>> existing data on the disk medium". Normally I would consult the logic >>> manuals :-( >>> >>> When you allocate an HFS or linear data set, does AMS preformat all of the >>> tracks? When you format a zFS, does that force formatting of all tracks? >>> Can you provide references that I can cite for the answers? >>> >>> Thanks. >>> >>> >>> >>> -- >>> Shmuel (Seymour J.) Metz >>> http://mason.gmu.edu/~smetz3 >>> >>> -- >>> For IBM-MAIN subscribe / signoff / archive access instructions, >>> send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN >> >> >> -- >> Mike A Schwab, Springfield IL USA >> Where do Forest Rangers go to get away from it all? >> >> == Jeśli nie jesteś adresatem tej wiadomości: - powiadom nas o tym w mailu zwrotnym (dziękujemy!), - usuń trwale tę wiadomość (i wszystkie kopie, które wydrukowałeś lub zapisałeś na dysku). Wiadomość ta może zawierać chronione prawem informacje, które może wykorzystać tylko adresat.Przypominamy, że każdy, kto rozpowszechnia (kopiuje, rozprowadza) tę wiadomość lub podejmuje podobne działania, narusza prawo i może podlegać karze. mBank S.A. z siedzibą w Warszawie, ul. Senatorska 18, 00-950 Warszawa,http://secure-web.cisco.com/1ISsJxe3gUoQRotlF_0jTbuqotAWxbHEXflN-NIw9crn4KpwKd32d1oNWFB0hZVjl9huaBfHygbzRjz4uIrkE5YGusOgujYGlR47c__L63dotSshe5dtts2LEtTfAVEjayMKMFCvRuoToKvqjvcZZ-MZSgykgkEOksIRp2PxDr0CbT502QGFIvVGmmmV7L-ITxvfS0dukH6dwXrrE_A3dinN7bcOQTjBNwazJFzQpSFuNAee-cMbNH3HH2IbuzRbE74FqzNkCvdTbz1PpMvPWt-KWUKTQLXIJPRG2EwZHHiVKg8BQZjdzzNJYY6FHne-5OuEWYgjJp1ezhUWuX4gUAYxg1mzg2QDg3tgLqcsx2VeUuLL9RwArKs8G_Pn4tiY4n0NuCc7YNYf0JINZpx-1zE4nrtYvAWgNkrJBjDqqjQ9BuDcidd6ik3p5-xjEfXjT/http%3A%2F%2Fwww.mBank.pl, e-mail: kont...@mbank.pl. Sąd Rejonowy dla m. st. Warszawy XII Wydział Gospodarczy Krajowego Rejest
Re: Does allocating an HFS or zFS erase all existing data?intervals formatted?
Excuse me, but IMHO RECOVERY does "format" CIs within CA - that means proper values are written into CIDF and RDF (in any). That means VSAM knows the CI is empty, or partially filled. Unused space within CI is not cleared, there is no need for that. From the other hand physically full block is written. PB is usually equal CI (let's focus on this case), so everytime you write CIDF, you write full block. The rest of block may be zeros or just any value, but not previous content from the track. So - it seems the goal of RECOVERY is to write control fields, but the way its being done means whole CIs are rewritten. IMHO nevermind, because both SPEED and RECOVERY do not "format" all possible CI's within disk extent. So, even with RECOVERY it is possible to have residual data within the extent. Still hard to read, but not impossible. -- Radoslaw Skorupka Lodz, Poland W dniu 15.05.2020 o 21:17, Mike Schwab pisze: https://www.ibm.com/support/knowledgecenter/SSLTBW_2.4.0/com.ibm.zos.v2r4.idai200/da6i2118.htm Discussion on Speed / Recovery option. On Fri, May 15, 2020 at 5:34 PM Seymour J Metz wrote: Do you have something that I can cite for that, preferably something that all wiki readers can look at? -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of Mike Schwab [mike.a.sch...@gmail.com] Sent: Friday, May 15, 2020 1:14 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Does allocating an HFS or zFS erase all existing data?intervals formatted? All VSAM datasets including Linear are formatted when created. The disk space used is not allocated to any other datasets. Previous data left by deleted datasets is usually left in place (erase on delete is an option but not used frequently) but frequently overwritten in a short time so restoring a deleted data set is almost always impossible. On Fri, May 15, 2020 at 4:25 PM Seymour J Metz wrote: I want to edit the wiki article [[Disk formatting]] to clarify the statement "s a general rule,[nb 1] formatting a disk erases most if not all existing data on the disk medium". Normally I would consult the logic manuals :-( When you allocate an HFS or linear data set, does AMS preformat all of the tracks? When you format a zFS, does that force formatting of all tracks? Can you provide references that I can cite for the answers? Thanks. -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? == Jeśli nie jesteś adresatem tej wiadomości: - powiadom nas o tym w mailu zwrotnym (dziękujemy!), - usuń trwale tę wiadomość (i wszystkie kopie, które wydrukowałeś lub zapisałeś na dysku). Wiadomość ta może zawierać chronione prawem informacje, które może wykorzystać tylko adresat.Przypominamy, że każdy, kto rozpowszechnia (kopiuje, rozprowadza) tę wiadomość lub podejmuje podobne działania, narusza prawo i może podlegać karze. mBank S.A. z siedzibą w Warszawie, ul. Senatorska 18, 00-950 Warszawa,www.mBank.pl, e-mail: kont...@mbank.pl. Sąd Rejonowy dla m. st. Warszawy XII Wydział Gospodarczy Krajowego Rejestru Sądowego, KRS 025237, NIP: 526-021-50-88. Kapitał zakładowy (opłacony w całości) według stanu na 01.01.2020 r. wynosi 169.401.468 złotych. If you are not the addressee of this message: - let us know by replying to this e-mail (thank you!), - delete this message permanently (including all the copies which you have printed out or saved). This message may contain legally protected information, which may be used exclusively by the addressee.Please be reminded that anyone who disseminates (copies, distributes) this message or takes any similar action, violates the law and may be penalised. mBank S.A. with its registered office in Warsaw, ul. Senatorska 18, 00-950 Warszawa,www.mBank.pl, e-mail: kont...@mbank.pl. District Court for the Capital City of Warsaw, 12th Commercial Division of the National Court Register, KRS 025237, NIP: 526-021-50-88. Fully paid-up share capital amounting to PLN 169.401.468 as at 1 January 2020. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Does allocating an HFS or zFS erase all existing data?intervals formatted?
Is that applicable to linear, which is what zFS uses? -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of Mike Schwab [mike.a.sch...@gmail.com] Sent: Friday, May 15, 2020 3:17 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Does allocating an HFS or zFS erase all existing data?intervals formatted? https://www.ibm.com/support/knowledgecenter/SSLTBW_2.4.0/com.ibm.zos.v2r4.idai200/da6i2118.htm Discussion on Speed / Recovery option. On Fri, May 15, 2020 at 5:34 PM Seymour J Metz wrote: > > Do you have something that I can cite for that, preferably something that all > wiki readers can look at? > > > -- > Shmuel (Seymour J.) Metz > http://mason.gmu.edu/~smetz3 > > > From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of > Mike Schwab [mike.a.sch...@gmail.com] > Sent: Friday, May 15, 2020 1:14 PM > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: Re: Does allocating an HFS or zFS erase all existing data?intervals > formatted? > > All VSAM datasets including Linear are formatted when created. The > disk space used is not allocated to any other datasets. Previous data > left by deleted datasets is usually left in place (erase on delete is > an option but not used frequently) but frequently overwritten in a > short time so restoring a deleted data set is almost always > impossible. > > On Fri, May 15, 2020 at 4:25 PM Seymour J Metz wrote: > > > > I want to edit the wiki article [[Disk formatting]] to clarify the > > statement "s a general rule,[nb 1] formatting a disk erases most if not all > > existing data on the disk medium". Normally I would consult the logic > > manuals :-( > > > > When you allocate an HFS or linear data set, does AMS preformat all of the > > tracks? When you format a zFS, does that force formatting of all tracks? > > Can you provide references that I can cite for the answers? > > > > Thanks. > > > > > > > > -- > > Shmuel (Seymour J.) Metz > > http://mason.gmu.edu/~smetz3 > > > > -- > > For IBM-MAIN subscribe / signoff / archive access instructions, > > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > > > > -- > Mike A Schwab, Springfield IL USA > Where do Forest Rangers go to get away from it all? > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Does allocating an HFS or zFS erase all existing data?intervals formatted?
https://www.ibm.com/support/knowledgecenter/SSLTBW_2.4.0/com.ibm.zos.v2r4.idai200/da6i2118.htm Discussion on Speed / Recovery option. On Fri, May 15, 2020 at 5:34 PM Seymour J Metz wrote: > > Do you have something that I can cite for that, preferably something that all > wiki readers can look at? > > > -- > Shmuel (Seymour J.) Metz > http://mason.gmu.edu/~smetz3 > > > From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of > Mike Schwab [mike.a.sch...@gmail.com] > Sent: Friday, May 15, 2020 1:14 PM > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: Re: Does allocating an HFS or zFS erase all existing data?intervals > formatted? > > All VSAM datasets including Linear are formatted when created. The > disk space used is not allocated to any other datasets. Previous data > left by deleted datasets is usually left in place (erase on delete is > an option but not used frequently) but frequently overwritten in a > short time so restoring a deleted data set is almost always > impossible. > > On Fri, May 15, 2020 at 4:25 PM Seymour J Metz wrote: > > > > I want to edit the wiki article [[Disk formatting]] to clarify the > > statement "s a general rule,[nb 1] formatting a disk erases most if not all > > existing data on the disk medium". Normally I would consult the logic > > manuals :-( > > > > When you allocate an HFS or linear data set, does AMS preformat all of the > > tracks? When you format a zFS, does that force formatting of all tracks? > > Can you provide references that I can cite for the answers? > > > > Thanks. > > > > > > > > -- > > Shmuel (Seymour J.) Metz > > http://mason.gmu.edu/~smetz3 > > > > -- > > For IBM-MAIN subscribe / signoff / archive access instructions, > > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > > > > -- > Mike A Schwab, Springfield IL USA > Where do Forest Rangers go to get away from it all? > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Does allocating an HFS or zFS erase all existing data?intervals formatted?
Do you have something that I can cite for that, preferably something that all wiki readers can look at? -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of Mike Schwab [mike.a.sch...@gmail.com] Sent: Friday, May 15, 2020 1:14 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Does allocating an HFS or zFS erase all existing data?intervals formatted? All VSAM datasets including Linear are formatted when created. The disk space used is not allocated to any other datasets. Previous data left by deleted datasets is usually left in place (erase on delete is an option but not used frequently) but frequently overwritten in a short time so restoring a deleted data set is almost always impossible. On Fri, May 15, 2020 at 4:25 PM Seymour J Metz wrote: > > I want to edit the wiki article [[Disk formatting]] to clarify the statement > "s a general rule,[nb 1] formatting a disk erases most if not all existing > data on the disk medium". Normally I would consult the logic manuals :-( > > When you allocate an HFS or linear data set, does AMS preformat all of the > tracks? When you format a zFS, does that force formatting of all tracks? Can > you provide references that I can cite for the answers? > > Thanks. > > > > -- > Shmuel (Seymour J.) Metz > http://mason.gmu.edu/~smetz3 > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Does allocating an HFS or zFS erase all existing data?intervals formatted?
Hi Mike, You said: "... All VSAm Datasets including Linear are formatted when created ...". Is this true for ESDSs? Where is this documented? Thanks and regards, David All VSAM datasets including Linear are formatted when created On 2020-05-15 13:14, Mike Schwab wrote: All VSAM datasets including Linear are formatted when created. The disk space used is not allocated to any other datasets. Previous data left by deleted datasets is usually left in place (erase on delete is an option but not used frequently) but frequently overwritten in a short time so restoring a deleted data set is almost always impossible. On Fri, May 15, 2020 at 4:25 PM Seymour J Metz wrote: I want to edit the wiki article [[Disk formatting]] to clarify the statement "s a general rule,[nb 1] formatting a disk erases most if not all existing data on the disk medium". Normally I would consult the logic manuals :-( When you allocate an HFS or linear data set, does AMS preformat all of the tracks? When you format a zFS, does that force formatting of all tracks? Can you provide references that I can cite for the answers? Thanks. -- Shmuel (Seymour J.) Metz https://eur03.safelinks.protection.outlook.com/?url=http:%2F%2Fmason.gmu.edu%2F~smetz3&data=02%7C01%7C%7C74a32c4b87de48c2be2c08d7f8f38371%7C84df9e7fe9f640afb435%7C1%7C0%7C637251597081119599&sdata=nFq8774EHZTWnk8RfMeRQIFWs8qBqBpq5TQ1VvgGuy4%3D&reserved=0 -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Does allocating an HFS or zFS erase all existing data?intervals formatted?
All VSAM datasets including Linear are formatted when created. The disk space used is not allocated to any other datasets. Previous data left by deleted datasets is usually left in place (erase on delete is an option but not used frequently) but frequently overwritten in a short time so restoring a deleted data set is almost always impossible. On Fri, May 15, 2020 at 4:25 PM Seymour J Metz wrote: > > I want to edit the wiki article [[Disk formatting]] to clarify the statement > "s a general rule,[nb 1] formatting a disk erases most if not all existing > data on the disk medium". Normally I would consult the logic manuals :-( > > When you allocate an HFS or linear data set, does AMS preformat all of the > tracks? When you format a zFS, does that force formatting of all tracks? Can > you provide references that I can cite for the answers? > > Thanks. > > > > -- > Shmuel (Seymour J.) Metz > http://mason.gmu.edu/~smetz3 > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Does allocating an HFS or zFS erase all existing data?intervals formatted?
I want to edit the wiki article [[Disk formatting]] to clarify the statement "s a general rule,[nb 1] formatting a disk erases most if not all existing data on the disk medium". Normally I would consult the logic manuals :-( When you allocate an HFS or linear data set, does AMS preformat all of the tracks? When you format a zFS, does that force formatting of all tracks? Can you provide references that I can cite for the answers? Thanks. -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
