Re: Simple VSAM question on sizing INDEX component
Lizette, Without meaning to 'teach grannies to suck eggs', the index component of a VSAM KSDS contains an 'INDEX SET' and a 'SEQUENCE SET'. The 'INDEX SET' contains one or more CIs whose records/entries point at 'SEQUENCE SET' CIs. The records in the 'INDEX SET' are pointers to CAs, i.e. to 'SEQUENCE SET' CIs. The records in the 'SEQUENCE SET' CIs are pointers to DATA CIs. In both cases, these records contain the highest KSDS keys in the CA's CIs pointed at (for 'INDEX SET') or contain the highest KSDS CI key within a CA (for 'SEQUENCE SET') - thus allowing determination of the CI that contains the keyed DATA record, within the CA. Both 'INDEX SET' and 'SEQUENCE SET' CIs are subject to INDEX CI-splits when new 'user' keyed DATA records are inserted. The process of locating/accessing a VSAM KSDS DATA record is then as follows: - From the 'INDEX SET' determine which CA has the CI that contains the keyed DATA record. - From the 'SEQUENCE SET' determine which CI within that CA contains the keyed DATA record. - From this CI's CIDF and RDFs now locate/access the keyed DATA record. Performance will be degraded if the 'INDEX SET' has suffered CI-splits, because its lower level CIs will then have to be I/O fetched to read their pointers to the 'SEQUENCE SET' CIs. I would suggest that you dump your VSAM's INDEX dataset (e.g. "PRINT IDS() OUTFILE()") to check for INDEX CI-splits - and down to what level - then figure out how to redefine your VSAM INDEX (CISZ, CYL/TRK etc.) from there. HTH. Cheers, Chris Poncelet (retired sysprog) On 31/08/2020 13:48, Lizette Koehler wrote: > According to the LISTC it has CA-RECLAIM(YES) > > > > -Original Message- > From: IBM Mainframe Discussion List On Behalf Of > Allan Staller > Sent: Monday, August 31, 2020 5:17 AM > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: Re: Simple VSAM question on sizing INDEX component > > Is the data set (and dfsms) set up for CA_RECLAIM? > > -Original Message- > From: IBM Mainframe Discussion List On Behalf Of > Lizette Koehler > Sent: Sunday, August 30, 2020 5:12 PM > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: Simple VSAM question on sizing INDEX component > > [CAUTION: This Email is from outside the Organization. Unless you trust the > sender, Don’t click links or open attachments as it may be a Phishing email, > which can steal your Information and compromise your Computer.] > > List - > > > > I have a VSAM Dataset that has grown over the years. When it was set up - > the INDEX space was left to default > > > > I am wondering if it makes sense to override the Track Allocation and put it > in Cylinders. > > > > We are noticing a little bit of an increase in run time during reorg. I was > wondering if this might be due to the data set having 3.4GB now. This file > is EA/EF so it can grow > > > > Over 4500 Cylinders on the Data > > And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB > > > > > > During reorg we offload records to an archive then reload the current data > back in. > > > > This may be something I cannot improve on, just thought I would see if there > are any insights I am missing. > > > > Process: > Offload the data to a temp file > > Archive records older than 2 weeks > > Del/Def VSAM dataset > > Reload current records to VSAM dataset > > > > This runs daily > > > Thank you > > > > Lizette > > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, send email to > lists...@listserv.ua.edu with the message: INFO IBM-MAIN > ::DISCLAIMER:: > > The contents of this e-mail and any attachment(s) are confidential and > intended for the named recipient(s) only. E-mail transmission is not > guaranteed to be secure or error-free as information could be intercepted, > corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses > in transmission. The e mail and its contents (with or without referred > errors) shall therefore not attach any liability on the originator or HCL or > its affiliates. Views or opinions, if any, presented in this email are solely > those of the author and may not necessarily reflect the views or opinions of > HCL or its affiliates. Any form of reproduction, dissemination, copying, > disclosure, modification, distribution and / or publication of this message > without the prior written consent of authorized representative of HCL is > strictly prohibited. If you have received this email in error please delete > it and notify the sender immediately. Before opening any email and/or
Re: Simple VSAM question on sizing INDEX component
Lizette, I think that is the default now, but if CA-RECLAIM isn’t turned on in IGDSMSxx then nothing is occurring. _ Dave Jousma AVP | Director, Technology Engineering Fifth Third Bank | 1830 East Paris Ave, SE | MD RSCB2H | Grand Rapids, MI 49546 616.653.8429 | fax: 616.653.2717 -Original Message- From: IBM Mainframe Discussion List On Behalf Of Lizette Koehler Sent: Monday, August 31, 2020 8:48 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Simple VSAM question on sizing INDEX component **CAUTION EXTERNAL EMAIL** **DO NOT open attachments or click on links from unknown senders or unexpected emails** According to the LISTC it has CA-RECLAIM(YES) -Original Message- From: IBM Mainframe Discussion List On Behalf Of Allan Staller Sent: Monday, August 31, 2020 5:17 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Simple VSAM question on sizing INDEX component Is the data set (and dfsms) set up for CA_RECLAIM? -Original Message- From: IBM Mainframe Discussion List On Behalf Of Lizette Koehler Sent: Sunday, August 30, 2020 5:12 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Simple VSAM question on sizing INDEX component [CAUTION: This Email is from outside the Organization. Unless you trust the sender, Don’t click links or open attachments as it may be a Phishing email, which can steal your Information and compromise your Computer.] List - I have a VSAM Dataset that has grown over the years. When it was set up - the INDEX space was left to default I am wondering if it makes sense to override the Track Allocation and put it in Cylinders. We are noticing a little bit of an increase in run time during reorg. I was wondering if this might be due to the data set having 3.4GB now. This file is EA/EF so it can grow Over 4500 Cylinders on the Data And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB During reorg we offload records to an archive then reload the current data back in. This may be something I cannot improve on, just thought I would see if there are any insights I am missing. Process: Offload the data to a temp file Archive records older than 2 weeks Del/Def VSAM dataset Reload current records to VSAM dataset This runs daily Thank you Lizette -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ::DISCLAIMER:: The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. E-mail transmission is not guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses in transmission. The e mail and its contents (with or without referred errors) shall therefore not attach any liability on the originator or HCL or its affiliates. Views or opinions, if any, presented in this email are solely those of the author and may not necessarily reflect the views or opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of authorized representative of HCL is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any email and/or attachments, please check them for viruses and other defects. -- 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 **CAUTION EXTERNAL EMAIL** **DO NOT open attachments or click on links from unknown senders or unexpected emails** This e-mail transmission contains information that is confidential and may be privileged. It is intended only for the addressee(s) named above. If you receive this e-mail in error, please do not read, copy or disseminate it in any manner. If you are not the intended recipient, any disclosure, copying, distribution or use of the contents of this information is prohibited. Please reply to the message immediately by informing the sender that the message was misdirected. After replying, please erase it from your computer system. Your assistance in correcting this error is appreciated. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email
Re: Simple VSAM question on sizing INDEX component
According to the LISTC it has CA-RECLAIM(YES) -Original Message- From: IBM Mainframe Discussion List On Behalf Of Allan Staller Sent: Monday, August 31, 2020 5:17 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Simple VSAM question on sizing INDEX component Is the data set (and dfsms) set up for CA_RECLAIM? -Original Message- From: IBM Mainframe Discussion List On Behalf Of Lizette Koehler Sent: Sunday, August 30, 2020 5:12 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Simple VSAM question on sizing INDEX component [CAUTION: This Email is from outside the Organization. Unless you trust the sender, Don’t click links or open attachments as it may be a Phishing email, which can steal your Information and compromise your Computer.] List - I have a VSAM Dataset that has grown over the years. When it was set up - the INDEX space was left to default I am wondering if it makes sense to override the Track Allocation and put it in Cylinders. We are noticing a little bit of an increase in run time during reorg. I was wondering if this might be due to the data set having 3.4GB now. This file is EA/EF so it can grow Over 4500 Cylinders on the Data And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB During reorg we offload records to an archive then reload the current data back in. This may be something I cannot improve on, just thought I would see if there are any insights I am missing. Process: Offload the data to a temp file Archive records older than 2 weeks Del/Def VSAM dataset Reload current records to VSAM dataset This runs daily Thank you Lizette -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ::DISCLAIMER:: The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. E-mail transmission is not guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses in transmission. The e mail and its contents (with or without referred errors) shall therefore not attach any liability on the originator or HCL or its affiliates. Views or opinions, if any, presented in this email are solely those of the author and may not necessarily reflect the views or opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of authorized representative of HCL is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any email and/or attachments, please check them for viruses and other defects. -- 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: Simple VSAM question on sizing INDEX component
Is the data set (and dfsms) set up for CA_RECLAIM? -Original Message- From: IBM Mainframe Discussion List On Behalf Of Lizette Koehler Sent: Sunday, August 30, 2020 5:12 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Simple VSAM question on sizing INDEX component [CAUTION: This Email is from outside the Organization. Unless you trust the sender, Don’t click links or open attachments as it may be a Phishing email, which can steal your Information and compromise your Computer.] List - I have a VSAM Dataset that has grown over the years. When it was set up - the INDEX space was left to default I am wondering if it makes sense to override the Track Allocation and put it in Cylinders. We are noticing a little bit of an increase in run time during reorg. I was wondering if this might be due to the data set having 3.4GB now. This file is EA/EF so it can grow Over 4500 Cylinders on the Data And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB During reorg we offload records to an archive then reload the current data back in. This may be something I cannot improve on, just thought I would see if there are any insights I am missing. Process: Offload the data to a temp file Archive records older than 2 weeks Del/Def VSAM dataset Reload current records to VSAM dataset This runs daily Thank you Lizette -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ::DISCLAIMER:: The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. E-mail transmission is not guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses in transmission. The e mail and its contents (with or without referred errors) shall therefore not attach any liability on the originator or HCL or its affiliates. Views or opinions, if any, presented in this email are solely those of the author and may not necessarily reflect the views or opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of authorized representative of HCL is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any email and/or attachments, please check them for viruses and other defects. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Simple VSAM question on sizing INDEX component
FWIW This VSAM index issue is most likely due to CI/CA splits. I would suggest unloading/deleting/reloading the complete VSAM cluster (if necessary ALTERing the original VSAM cluster to some temp other names instead of deleting it, after the unload and as a fall-back) to fix this. A FREESPACE(ca,ci) on reload is unlikely to achieve anything other than to waste DASD space. A dump of its current VSAM index would show what the actual problem is. On 31/08/2020 04:16, Mike Schwab wrote: > Well a 1, 2, 4, 7, 8, 11, 13, or 14 track index has 1 track CAs, 3, 6, > 9, or 12 for a 3 track CA, 5 or 10 for a 5 track CA, 15 tracks or more > for a 1 cylinder CA. Details then vary based on key size, > FREESPACE(ca ci) values, etc. Assuming reload after backup, delete, > define, restore. If you just delete old records then use will go up > with free space left by delete but insert doesn't use that space. > I.E. time stamp particularly bad primary key. > > On Sun, Aug 30, 2020 at 8:07 PM Michael Watkins > <032966e74d0f-dmarc-requ...@listserv.ua.edu> wrote: >> More efficient in terms of fewer index LEVELs as Tony Thigpen may have been >> getting at? I thought the number of LEVELs was contingent on the the size of >> the file and the number of CI and CA splits the index component had endured >> and not the allocation of contiguous space for the index component on DASD. >> A REORG should reduce the number of LEVELs to its smallest possible number, >> no? >> >> -Original Message- >> From: IBM Mainframe Discussion List On Behalf Of >> Mike Schwab >> Sent: Sunday, August 30, 2020 7:48 PM >> To: IBM-MAIN@LISTSERV.UA.EDU >> Subject: Re: Simple VSAM question on sizing INDEX component >> >> CAUTION: This email originated from outside of the Texas Comptroller's email >> system. >> DO NOT click links or open attachments unless you expect them from the >> sender and know the content is safe. >> >> CYL(4 1) should leave one cylinder empty. Cylinder CA will result is a more >> efficient index. >> >> On Sun, Aug 30, 2020 at 5:12 PM Lizette Koehler >> wrote: >>> List - >>> >>> I have a VSAM Dataset that has grown over the years. When it was set >>> up - the INDEX space was left to default >>> >>> I am wondering if it makes sense to override the Track Allocation and >>> put it in Cylinders. >>> >>> We are noticing a little bit of an increase in run time during reorg. >>> I was wondering if this might be due to the data set having 3.4GB now. >>> >>> This file is EA/EF so it can grow >>> >>> Over 4500 Cylinders on the Data >>> >>> And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB >>> During reorg we offload records to an archive then reload the current >>> data back in >>> >>> This may be something I cannot improve on, just thought I would see if >>> there are any insights I am missing. >>> >>> Process: >>> Offload the data to a temp file >>> Archive records older than 2 weeks >>> Del/Def VSAM dataset >>> Reload current records to VSAM dataset >>> This runs daily >>> >>> Thank you >>> Lizette >>> >>> -- >>> 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 > > -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Simple VSAM question on sizing INDEX component
Well a 1, 2, 4, 7, 8, 11, 13, or 14 track index has 1 track CAs, 3, 6, 9, or 12 for a 3 track CA, 5 or 10 for a 5 track CA, 15 tracks or more for a 1 cylinder CA. Details then vary based on key size, FREESPACE(ca ci) values, etc. Assuming reload after backup, delete, define, restore. If you just delete old records then use will go up with free space left by delete but insert doesn't use that space. I.E. time stamp particularly bad primary key. On Sun, Aug 30, 2020 at 8:07 PM Michael Watkins <032966e74d0f-dmarc-requ...@listserv.ua.edu> wrote: > > More efficient in terms of fewer index LEVELs as Tony Thigpen may have been > getting at? I thought the number of LEVELs was contingent on the the size of > the file and the number of CI and CA splits the index component had endured > and not the allocation of contiguous space for the index component on DASD. A > REORG should reduce the number of LEVELs to its smallest possible number, no? > > -Original Message- > From: IBM Mainframe Discussion List On Behalf Of > Mike Schwab > Sent: Sunday, August 30, 2020 7:48 PM > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: Re: Simple VSAM question on sizing INDEX component > > CAUTION: This email originated from outside of the Texas Comptroller's email > system. > DO NOT click links or open attachments unless you expect them from the sender > and know the content is safe. > > CYL(4 1) should leave one cylinder empty. Cylinder CA will result is a more > efficient index. > > On Sun, Aug 30, 2020 at 5:12 PM Lizette Koehler > wrote: > > > > List - > > > > I have a VSAM Dataset that has grown over the years. When it was set > > up - the INDEX space was left to default > > > > I am wondering if it makes sense to override the Track Allocation and > > put it in Cylinders. > > > > We are noticing a little bit of an increase in run time during reorg. > > I was wondering if this might be due to the data set having 3.4GB now. > > > > This file is EA/EF so it can grow > > > > Over 4500 Cylinders on the Data > > > > And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB > > During reorg we offload records to an archive then reload the current > > data back in > > > > This may be something I cannot improve on, just thought I would see if > > there are any insights I am missing. > > > > Process: > > Offload the data to a temp file > > Archive records older than 2 weeks > > Del/Def VSAM dataset > > Reload current records to VSAM dataset > > This runs daily > > > > Thank you > > Lizette > > > > -- > > 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: Simple VSAM question on sizing INDEX component
[Default] On 30 Aug 2020 15:12:07 -0700, in bit.listserv.ibm-main stars...@mindspring.com (Lizette Koehler) wrote: >List - > > > >I have a VSAM Dataset that has grown over the years. When it was set up - >the INDEX space was left to default > One other thing to check for in addition to the other recommendations given is whether or not the file should have grown this large. I ran into a case in one shop I was at where records were getting on the file but because of a coding error only certain ones were getting updated and removed. I was a systems programmer who went back into applications and was actually tracking down why a run time had increased. Clark Morris > >I am wondering if it makes sense to override the Track Allocation and put it >in Cylinders. > > > >We are noticing a little bit of an increase in run time during reorg. I was >wondering if this might be due to the data set having 3.4GB now. This file >is EA/EF so it can grow > > > >Over 4500 Cylinders on the Data > >And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB > > > > > >During reorg we offload records to an archive then reload the current data >back in. > > > >This may be something I cannot improve on, just thought I would see if there >are any insights I am missing. > > > >Process: >Offload the data to a temp file > >Archive records older than 2 weeks > >Del/Def VSAM dataset > >Reload current records to VSAM dataset > > > >This runs daily > > >Thank you > > > >Lizette > > >-- >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: Simple VSAM question on sizing INDEX component
Number of index levels is affected by data CA/CI sizes, index CA/CI sizes and how well the key "compresses" between adjacent CIs. Until you have a loaded file, you can't be positive about how many levels you have. But, once you have it loaded, it's easier to make adjustments prior to another re-load. Too many index levels usually indicate something else is not right. Tony Thigpen Michael Watkins wrote on 8/30/20 9:07 PM: More efficient in terms of fewer index LEVELs as Tony Thigpen may have been getting at? I thought the number of LEVELs was contingent on the the size of the file and the number of CI and CA splits the index component had endured and not the allocation of contiguous space for the index component on DASD. A REORG should reduce the number of LEVELs to its smallest possible number, no? -Original Message- From: IBM Mainframe Discussion List On Behalf Of Mike Schwab Sent: Sunday, August 30, 2020 7:48 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Simple VSAM question on sizing INDEX component CAUTION: This email originated from outside of the Texas Comptroller's email system. DO NOT click links or open attachments unless you expect them from the sender and know the content is safe. CYL(4 1) should leave one cylinder empty. Cylinder CA will result is a more efficient index. On Sun, Aug 30, 2020 at 5:12 PM Lizette Koehler wrote: List - I have a VSAM Dataset that has grown over the years. When it was set up - the INDEX space was left to default I am wondering if it makes sense to override the Track Allocation and put it in Cylinders. We are noticing a little bit of an increase in run time during reorg. I was wondering if this might be due to the data set having 3.4GB now. This file is EA/EF so it can grow Over 4500 Cylinders on the Data And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB During reorg we offload records to an archive then reload the current data back in This may be something I cannot improve on, just thought I would see if there are any insights I am missing. Process: Offload the data to a temp file Archive records older than 2 weeks Del/Def VSAM dataset Reload current records to VSAM dataset This runs daily Thank you Lizette -- 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 -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Simple VSAM question on sizing INDEX component
More efficient in terms of fewer index LEVELs as Tony Thigpen may have been getting at? I thought the number of LEVELs was contingent on the the size of the file and the number of CI and CA splits the index component had endured and not the allocation of contiguous space for the index component on DASD. A REORG should reduce the number of LEVELs to its smallest possible number, no? -Original Message- From: IBM Mainframe Discussion List On Behalf Of Mike Schwab Sent: Sunday, August 30, 2020 7:48 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Simple VSAM question on sizing INDEX component CAUTION: This email originated from outside of the Texas Comptroller's email system. DO NOT click links or open attachments unless you expect them from the sender and know the content is safe. CYL(4 1) should leave one cylinder empty. Cylinder CA will result is a more efficient index. On Sun, Aug 30, 2020 at 5:12 PM Lizette Koehler wrote: > > List - > > I have a VSAM Dataset that has grown over the years. When it was set > up - the INDEX space was left to default > > I am wondering if it makes sense to override the Track Allocation and > put it in Cylinders. > > We are noticing a little bit of an increase in run time during reorg. > I was wondering if this might be due to the data set having 3.4GB now. > > This file is EA/EF so it can grow > > Over 4500 Cylinders on the Data > > And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB > During reorg we offload records to an archive then reload the current > data back in > > This may be something I cannot improve on, just thought I would see if > there are any insights I am missing. > > Process: > Offload the data to a temp file > Archive records older than 2 weeks > Del/Def VSAM dataset > Reload current records to VSAM dataset > This runs daily > > Thank you > Lizette > > -- > 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: Simple VSAM question on sizing INDEX component
CYL(4 1) should leave one cylinder empty. Cylinder CA will result is a more efficient index. On Sun, Aug 30, 2020 at 5:12 PM Lizette Koehler wrote: > > List - > > > > I have a VSAM Dataset that has grown over the years. When it was set up - > the INDEX space was left to default > > > > I am wondering if it makes sense to override the Track Allocation and put it > in Cylinders. > > > > We are noticing a little bit of an increase in run time during reorg. I was > wondering if this might be due to the data set having 3.4GB now. This file > is EA/EF so it can grow > > > > Over 4500 Cylinders on the Data > > And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB > > > > > > During reorg we offload records to an archive then reload the current data > back in. > > > > This may be something I cannot improve on, just thought I would see if there > are any insights I am missing. > > > > Process: > Offload the data to a temp file > > Archive records older than 2 weeks > > Del/Def VSAM dataset > > Reload current records to VSAM dataset > > > > This runs daily > > > Thank you > > > > Lizette > > > -- > 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: Simple VSAM question on sizing INDEX component
How many index levels do you have? Tony Thigpen Lizette Koehler wrote on 8/30/20 6:11 PM: List - I have a VSAM Dataset that has grown over the years. When it was set up - the INDEX space was left to default I am wondering if it makes sense to override the Track Allocation and put it in Cylinders. We are noticing a little bit of an increase in run time during reorg. I was wondering if this might be due to the data set having 3.4GB now. This file is EA/EF so it can grow Over 4500 Cylinders on the Data And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB During reorg we offload records to an archive then reload the current data back in. This may be something I cannot improve on, just thought I would see if there are any insights I am missing. Process: Offload the data to a temp file Archive records older than 2 weeks Del/Def VSAM dataset Reload current records to VSAM dataset This runs daily Thank you Lizette -- 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: Simple VSAM question on sizing INDEX component
Of course, buffering will probably do the most to improve VSAM REORG times.
For the sequential reads through the cluster that are typical of REORG
activity, add the ',AMP=('BUFNI=x,BUFND=yyy')' parameter to the DD card, where
'x' equals the number of index component LEVELS displayed in the IDCAMS
'LISTCAT ENT() ALL' output and 'yyy' equals the number of data
component CIs in one data CA.
This will assure that every chain of channel commands reads an entire virtual
cylinder. When the virtual read/write heads cross a cylinder boundaries, the
channel program will lose control, so no more than a cylinder can be read or
written by a channel program.
To optimize the value of 'yyy' for BUFND, look at the data component of the
'LISTC ENT() ALL'. Find the values for 'CI/CA' and 'TRACKS/CA'. Since
there are 15 tracks in a 3390 cylinder, you can easily calculate the number of
data CIs in one cylinder. Add one to this value and use that for BUFND.
Why add one? Some pople say the code reserves one CI for SPLIT activity, even
when the odds of it occuring are low. Some people say adding one for a CI
reserved for SPLIT activity is an old-wives tale, but it seems to work.
-Original Message-
From: Michael Watkins
Sent: Sunday, August 30, 2020 6:00 PM
To: IBM Mainframe Discussion List
Cc: Michael Watkins
Subject: RE: Simple VSAM question on sizing INDEX component
The index component alone is 2.4 MB? 2,400,000/56664 = 43 tracks? Sure,
Allocate the index component as 4 or even 5 cylinders primary and a single
cylinder secondary.
If the cluster has changed significantly over time, I might also run an IDCAMS
EXAMINE command:
EXAMINE NAME() INDEXTEST DATATEST
And look for:
IDC01728I FOUND n EMPTY CONTROL AREAS THAT HAVE NOT BEEN RECLAIMED IDC11775I
nnn DATA COMPONENT CIS ARE ESTIMATED TO BE UNREACHABLE
These may indicate that you want to change the index CI size, although buffer
specifications may also have to change if you do.
And I assume you have already activated 'CA reclaim' for all pertinent
DATACLASes in ISMF.
-Original Message-
From: IBM Mainframe Discussion List On Behalf Of
Lizette Koehler
Sent: Sunday, August 30, 2020 5:12 PM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Simple VSAM question on sizing INDEX component
CAUTION: This email originated from outside of the Texas Comptroller's email
system.
DO NOT click links or open attachments unless you expect them from the sender
and know the content is safe.
List -
I have a VSAM Dataset that has grown over the years. When it was set up - the
INDEX space was left to default
I am wondering if it makes sense to override the Track Allocation and put it in
Cylinders.
We are noticing a little bit of an increase in run time during reorg. I was
wondering if this might be due to the data set having 3.4GB now. This file is
EA/EF so it can grow
Over 4500 Cylinders on the Data
And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB
During reorg we offload records to an archive then reload the current data back
in.
This may be something I cannot improve on, just thought I would see if there
are any insights I am missing.
Process:
Offload the data to a temp file
Archive records older than 2 weeks
Del/Def VSAM dataset
Reload current records to VSAM dataset
This runs daily
Thank you
Lizette
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Re: Simple VSAM question on sizing INDEX component
The index component alone is 2.4 MB? 2,400,000/56664 = 43 tracks? Sure, Allocate the index component as 4 or even 5 cylinders primary and a single cylinder secondary. If the cluster has changed significantly over time, I might also run an IDCAMS EXAMINE command: EXAMINE NAME() INDEXTEST DATATEST And look for: IDC01728I FOUND n EMPTY CONTROL AREAS THAT HAVE NOT BEEN RECLAIMED IDC11775I nnn DATA COMPONENT CIS ARE ESTIMATED TO BE UNREACHABLE These may indicate that you want to change the index CI size, although buffer specifications may also have to change if you do. And I assume you have already activated 'CA reclaim' for all pertinent DATACLASes in ISMF. -Original Message- From: IBM Mainframe Discussion List On Behalf Of Lizette Koehler Sent: Sunday, August 30, 2020 5:12 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Simple VSAM question on sizing INDEX component CAUTION: This email originated from outside of the Texas Comptroller's email system. DO NOT click links or open attachments unless you expect them from the sender and know the content is safe. List - I have a VSAM Dataset that has grown over the years. When it was set up - the INDEX space was left to default I am wondering if it makes sense to override the Track Allocation and put it in Cylinders. We are noticing a little bit of an increase in run time during reorg. I was wondering if this might be due to the data set having 3.4GB now. This file is EA/EF so it can grow Over 4500 Cylinders on the Data And the index is using tracks 2 pri and 11 sec - size is now 2.4 MB During reorg we offload records to an archive then reload the current data back in. This may be something I cannot improve on, just thought I would see if there are any insights I am missing. Process: Offload the data to a temp file Archive records older than 2 weeks Del/Def VSAM dataset Reload current records to VSAM dataset This runs daily Thank you Lizette -- 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
