Re: Is it bad to make one zlinux running on 2 z/vm?
Exactly what business problem are you trying to address by doing this? Compare what you're doing to an Intel world implementation. Would you ever place two Intel boxes sharing disk, and with no knowledge of each other, side by side, and boot both systems from the same root disk? What results would you expect to get? How would you control the disk access to avoid collisions? And what business problem do you expect to solve by doing this? Are you really after a hot spare arrangement? Or an active / active cluster? These things would both be realized by creating two different systems, one running in each LPAR. Take a step back and a deep breath, and then look at what you want to do, in terms of how you would do it on separate physical Linux systems. Then fold the technique into your virtual implementation. -- Robert P. Nix Mayo Foundation.~. RO-OE-5-55 200 First Street SW/V\ 507-284-0844 Rochester, MN 55905 /( )\ -^^-^^ In theory, theory and practice are the same, but in practice, theory and practice are different. On 7/28/09 7:34 PM, Yoon-suk Cho isem...@gmail.com wrote: On Sat, Jul 25, 2009 at 7:30 AM, O'Brien, Dennis Ldennis.l.o'br...@bankofamerica.com wrote: Sunny, If you really have two guests up at the same time, using the same DASD, I can¹t believe that one or both of them haven¹t crashed. We have the same guests defined on two z/VM systems. We use the XLINK feature of CSE to make sure that only one of them can get the DASD read/write. If the second one is accidentally logged on, some code in PROFILE EXEC will discover that the DASD is read-only, message the operator, and log off. I really looking for the manual to setup linux system on two z/VM. Could you give me the detail manual ? Dennis O¹Brien That's one small step for (a) man, one giant leap for mankind. -- Neil Armstrong, 20 July 1969, Sea of Tranquility From: The IBM z/VM Operating System [mailto:ib...@listserv.uark.edu] On Behalf Of sunny...@wcb.ab.ca Sent: Friday, July 24, 2009 15:20 To: IBMVM@LISTSERV.UARK.EDU Subject: [IBMVM] Is it bad to make one zlinux running on 2 z/vm? We sometimes accidently turn on one linux guest on two z/VM systems. Both z/VM system has their own DIRMAINT and RACF. No RSCS. We add the same guest direct file to two z/VM so it makes the flexibility to boot. Is it bad to make one zlinux running on 2 z/vm? So far we didn't get any complaint. But I can't expain myself how. It has same ip address and the same dasds. sunny This message is intended only for the addressee. It may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately so that we may correct our internal records. Please then delete the original email. Thank you. (Sent by Webgate1)
Re: Is it bad to make one zlinux running on 2 z/vm?
The best solution for your problem is to couple the two systems with CSE, so that they¹ll know what the other is doing. Before we implemented CSE, we created a service we called Janus, which we ran in the profile of each Linux server during the CMS startup. The purpose was to look up which system the Linux guest was last started from, and to report a mismatch if there was a console, or log out immediately if the image was autologged. We still run Janus as a double check on things. If you¹d like the code, I can package it for you and explain what it is trying to do. -- Robert P. Nix Mayo Foundation.~. RO-OE-5-55 200 First Street SW/V\ 507-284-0844 Rochester, MN 55905 /( )\ -^^-^^ In theory, theory and practice are the same, but in practice, theory and practice are different. On 7/27/09 12:03 PM, sunny...@wcb.ab.ca sunny...@wcb.ab.ca wrote: Thanks folks, From the answers, I got : It is bad and must find a way to avoid it happening. What will happen if one zlinux running on 2 z/VM? There is a IP conflict and dasd R/W conflict. So it is the same as running two linux server sharing the same IP and the same disks? And z/VM has done nothing with it. Does my understating is correct? This message is intended only for the addressee. It may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately so that we may correct our internal records. Please then delete the original email. Thank you. (Sent by Webgate2)
Re: Is it bad to make one zlinux running on 2 z/vm?
I have not yet implemented CSE to protect our linuxes from being started on two different LPARs. I would be interested in getting a copy of your Janus code. Thanks for your assistance. /Tom Kern RPN01 wrote: The best solution for your problem is to couple the two systems with CSE, so that they’ll know what the other is doing. Before we implemented CSE, we created a service we called Janus, which we ran in the profile of each Linux server during the CMS startup. The purpose was to look up which system the Linux guest was last started from, and to report a mismatch if there was a console, or log out immediately if the image was autologged. We still run Janus as a double check on things. If you’d like the code, I can package it for you and explain what it is trying to do. -- Robert P. Nix Mayo Foundation.~. RO-OE-5-55 200 First Street SW/V\ 507-284-0844 Rochester, MN 55905 /( )\ -^^-^^ In theory, theory and practice are the same, but in practice, theory and practice are different.
Re: Is it bad to make one zlinux running on 2 z/vm?
Thanks, Robert! I do love to see the code. And I try to understand what is going on between z/VM and linux. Any books? RPN01 nix.rob...@mayo.edu Sent by: The IBM z/VM Operating System IBMVM@LISTSERV.UARK.EDU 07/28/2009 06:32 AM Please respond to The IBM z/VM Operating System IBMVM@LISTSERV.UARK.EDU To IBMVM@LISTSERV.UARK.EDU cc Subject Re: Is it bad to make one zlinux running on 2 z/vm? The best solution for your problem is to couple the two systems with CSE, so that they?ll know what the other is doing. Before we implemented CSE, we created a service we called Janus, which we ran in the profile of each Linux server during the CMS startup. The purpose was to look up which system the Linux guest was last started from, and to report a mismatch if there was a console, or log out immediately if the image was autologged. We still run Janus as a double check on things. If you?d like the code, I can package it for you and explain what it is trying to do. -- Robert P. Nix Mayo Foundation.~. RO-OE-5-55 200 First Street SW/V\ 507-284-0844 Rochester, MN 55905 /( )\ -^^-^^ In theory, theory and practice are the same, but in practice, theory and practice are different. On 7/27/09 12:03 PM, sunny...@wcb.ab.ca sunny...@wcb.ab.ca wrote: Thanks folks, From the answers, I got : It is bad and must find a way to avoid it happening. What will happen if one zlinux running on 2 z/VM? There is a IP conflict and dasd R/W conflict. So it is the same as running two linux server sharing the same IP and the same disks? And z/VM has done nothing with it. Does my understating is correct? This message is intended only for the addressee. It may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately so that we may correct our internal records. Please then delete the original email. Thank you. (Sent by Webgate2) Scanned by WCB Webgate2 AntiSpam/AntiVirus email gateway. This message is intended only for the addressee. It may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately so that we may correct our internal records. Please then delete the original email. Thank you. (Sent by Webgate2)
Re: Is it bad to make one zlinux running on 2 z/vm?
On 7/27/09 1:03 PM, sunny...@wcb.ab.ca sunny...@wcb.ab.ca wrote: What will happen if one zlinux running on 2 z/VM? There is a IP conflict and dasd R/W conflict. So it is the same as running two linux server sharing the same IP and the same disks? Exactly. And z/VM has done nothing with it. Unless you tell it to worry about it by enabling CSE.
Re: Is it bad to make one zlinux running on 2 z/vm?
On Sat, Jul 25, 2009 at 7:30 AM, O'Brien, Dennis Ldennis.l.o'br...@bankofamerica.com wrote: Sunny, If you really have two guests up at the same time, using the same DASD, I can’t believe that one or both of them haven’t crashed. We have the same guests defined on two z/VM systems. We use the XLINK feature of CSE to make sure that only one of them can get the DASD read/write. If the second one is accidentally logged on, some code in PROFILE EXEC will discover that the DASD is read-only, message the operator, and log off. I really looking for the manual to setup linux system on two z/VM. Could you give me the detail manual ? Dennis O’Brien That's one small step for (a) man, one giant leap for mankind. -- Neil Armstrong, 20 July 1969, Sea of Tranquility From: The IBM z/VM Operating System [mailto:ib...@listserv.uark.edu] On Behalf Of sunny...@wcb.ab.ca Sent: Friday, July 24, 2009 15:20 To: IBMVM@LISTSERV.UARK.EDU Subject: [IBMVM] Is it bad to make one zlinux running on 2 z/vm? We sometimes accidently turn on one linux guest on two z/VM systems. Both z/VM system has their own DIRMAINT and RACF. No RSCS. We add the same guest direct file to two z/VM so it makes the flexibility to boot. Is it bad to make one zlinux running on 2 z/vm? So far we didn't get any complaint. But I can't expain myself how. It has same ip address and the same dasds. sunny This message is intended only for the addressee. It may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately so that we may correct our internal records. Please then delete the original email. Thank you. (Sent by Webgate1)
Re: Is it bad to make one zlinux running on 2 z/vm?
I really looking for the manual to setup linux system on two z/VM. Could you give me the detail manual ? z/VM CP Planning and Administration Dennis O'Brien That's one small step for (a) man, one giant leap for mankind. -- Neil Armstrong, 20 July 1969, Sea of Tranquility -Original Message- From: The IBM z/VM Operating System [mailto:ib...@listserv.uark.edu] On Behalf Of Yoon-suk Cho Sent: Tuesday, July 28, 2009 17:35 To: IBMVM@LISTSERV.UARK.EDU Subject: Re: [IBMVM] Is it bad to make one zlinux running on 2 z/vm? On Sat, Jul 25, 2009 at 7:30 AM, O'Brien, Dennis Ldennis.l.o'br...@bankofamerica.com wrote: Sunny, If you really have two guests up at the same time, using the same DASD, I can't believe that one or both of them haven't crashed. We have the same guests defined on two z/VM systems. We use the XLINK feature of CSE to make sure that only one of them can get the DASD read/write. If the second one is accidentally logged on, some code in PROFILE EXEC will discover that the DASD is read-only, message the operator, and log off. I really looking for the manual to setup linux system on two z/VM. Could you give me the detail manual ? Dennis O'Brien That's one small step for (a) man, one giant leap for mankind. -- Neil Armstrong, 20 July 1969, Sea of Tranquility From: The IBM z/VM Operating System [mailto:ib...@listserv.uark.edu] On Behalf Of sunny...@wcb.ab.ca Sent: Friday, July 24, 2009 15:20 To: IBMVM@LISTSERV.UARK.EDU Subject: [IBMVM] Is it bad to make one zlinux running on 2 z/vm? We sometimes accidently turn on one linux guest on two z/VM systems. Both z/VM system has their own DIRMAINT and RACF. No RSCS. We add the same guest direct file to two z/VM so it makes the flexibility to boot. Is it bad to make one zlinux running on 2 z/vm? So far we didn't get any complaint. But I can't expain myself how. It has same ip address and the same dasds. sunny This message is intended only for the addressee. It may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately so that we may correct our internal records. Please then delete the original email. Thank you. (Sent by Webgate1)
Re: Is it bad to make one zlinux running on 2 z/vm?
If the two guests are truly using the same, R/W disks, then even if they don¹t know it yet, your disks are corrupted. I hope you have backups. We run the same guest on two different z/VM systems, ONE SYSTEM AT A TIME. It is very important that it not be logged in on both systems at the same time. This has been accidentally tested here and proven to be fatal to the Linux system. -- Robert P. Nix Mayo Foundation.~. RO-OE-5-55 200 First Street SW/V\ 507-284-0844 Rochester, MN 55905 /( )\ -^^-^^ In theory, theory and practice are the same, but in practice, theory and practice are different. On 7/24/09 5:30 PM, O'Brien, Dennis L dennis.l.o'br...@bankofamerica.com wrote: Sunny, If you really have two guests up at the same time, using the same DASD, I can¹t believe that one or both of them haven¹t crashed. We have the same guests defined on two z/VM systems. We use the XLINK feature of CSE to make sure that only one of them can get the DASD read/write. If the second one is accidentally logged on, some code in PROFILE EXEC will discover that the DASD is read-only, message the operator, and log off. Dennis O¹Brien That's one small step for (a) man, one giant leap for mankind. -- Neil Armstrong, 20 July 1969, Sea of Tranquility From: The IBM z/VM Operating System [mailto:ib...@listserv.uark.edu] On Behalf Of sunny...@wcb.ab.ca Sent: Friday, July 24, 2009 15:20 To: IBMVM@LISTSERV.UARK.EDU Subject: [IBMVM] Is it bad to make one zlinux running on 2 z/vm? We sometimes accidently turn on one linux guest on two z/VM systems. Both z/VM system has their own DIRMAINT and RACF. No RSCS. We add the same guest direct file to two z/VM so it makes the flexibility to boot. Is it bad to make one zlinux running on 2 z/vm? So far we didn't get any complaint. But I can't expain myself how. It has same ip address and the same dasds. sunny This message is intended only for the addressee. It may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately so that we may correct our internal records. Please then delete the original email. Thank you. (Sent by Webgate1)
Re: Is it bad to make one zlinux running on 2 z/vm?
Thanks folks, From the answers, I got : It is bad and must find a way to avoid it happening. What will happen if one zlinux running on 2 z/VM? There is a IP conflict and dasd R/W conflict. So it is the same as running two linux server sharing the same IP and the same disks? And z/VM has done nothing with it. Does my understating is correct? This message is intended only for the addressee. It may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately so that we may correct our internal records. Please then delete the original email. Thank you. (Sent by Webgate2)
Re: Is it bad to make one zlinux running on 2 z/vm?
On Sat, Jul 25, 2009 at 3:59 AM, David Boyesdbo...@sinenomine.net wrote: If you want this to work, then you need to configure CSE in your VM installation so that CP enforces that a user can be logged in on only one system at a time. You'll need RSCS (or an equivalent NJE implementation) and PVM to make this completely safe. RSCS and PVM don't add any safety to CSE beyond XLINK. XLINK is enough. Many shops have done this. Protecting some Linux disks with XLINK is enough at least to detect the situation. If you protect all you can even prevent damage completely. That's with components already part of your z/VM system. Suggesting that people would need to get special bids for PVM and license RSCS just scares them off and motivates them to walk around with a loaded gun. Rob
Re: Is it bad to make one zlinux running on 2 z/vm?
On 7/25/09 2:46 AM, Rob van der Heij rvdh...@gmail.com wrote: On Sat, Jul 25, 2009 at 3:59 AM, David Boyesdbo...@sinenomine.net wrote: If you want this to work, then you need to configure CSE in your VM installation so that CP enforces that a user can be logged in on only one system at a time. You'll need RSCS (or an equivalent NJE implementation) and PVM to make this completely safe. RSCS and PVM don't add any safety to CSE beyond XLINK. XLINK is enough. Many shops have done this. Um, what happens if/when a directory entry gets out of sync? Yes, you can invent a solution, but is the cost of maintaining something external that duplicates already available *and supported by IBM* function worth it? How do you handle scaling up the environment and monitoring tools? Who's paying for supporting your local hacks? Whose head rolls if/when it fails? Suggesting that people would need to get special bids for PVM and license RSCS just scares them off and motivates them to walk around with a loaded gun. I don't think I agree, and it's probably a worldview difference. IMHO, people are the expensive resource, and it's people that make mistakes. Clusters add opportunities to make mistakes linear to the number of nodes involved, and the impact of mistakes is exponential in terms of probability of causing the entire cluster to fail. The computers do what they are told, even if it's stupid. Any opportunity to take people out of the loop in terms of managing and maintaining the system adds to safety. So, I think that the exhortation to use CSE *as it was designed to be used* is actually a pretty good idea. You can certainly design additional semantics on top of the fully implemented CSE, but you're starting at a more advanced place with a richer toolkit, and the full CSE is a very helpful thing for implementing a reliable cluster. So, we can agree to differ. *I* think that starting with a fully-enabled CSE is a safer option in terms of having the SYSTEM manage itself and prevent at least two classes of possible stupid actions, and *I* consider having that extra safety a good thing, especially for a newbie who doesn't have the VM skills to implement the replacements. YMMV. -- db
Is it bad to make one zlinux running on 2 z/vm?
We sometimes accidently turn on one linux guest on two z/VM systems. Both z/VM system has their own DIRMAINT and RACF. No RSCS. We add the same guest direct file to two z/VM so it makes the flexibility to boot. Is it bad to make one zlinux running on 2 z/vm? So far we didn't get any complaint. But I can't expain myself how. It has same ip address and the same dasds. sunny This message is intended only for the addressee. It may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately so that we may correct our internal records. Please then delete the original email. Thank you. (Sent by Webgate1)
Re: Is it bad to make one zlinux running on 2 z/vm?
Sunny, If you really have two guests up at the same time, using the same DASD, I can’t believe that one or both of them haven’t crashed. We have the same guests defined on two z/VM systems. We use the XLINK feature of CSE to make sure that only one of them can get the DASD read/write. If the second one is accidentally logged on, some code in PROFILE EXEC will discover that the DASD is read-only, message the operator, and log off. Dennis O’Brien That's one small step for (a) man, one giant leap for mankind. -- Neil Armstrong, 20 July 1969, Sea of Tranquility From: The IBM z/VM Operating System [mailto:ib...@listserv.uark.edu] On Behalf Of sunny...@wcb.ab.ca Sent: Friday, July 24, 2009 15:20 To: IBMVM@LISTSERV.UARK.EDU Subject: [IBMVM] Is it bad to make one zlinux running on 2 z/vm? We sometimes accidently turn on one linux guest on two z/VM systems. Both z/VM system has their own DIRMAINT and RACF. No RSCS. We add the same guest direct file to two z/VM so it makes the flexibility to boot. Is it bad to make one zlinux running on 2 z/vm? So far we didn't get any complaint. But I can't expain myself how. It has same ip address and the same dasds. sunny This message is intended only for the addressee. It may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately so that we may correct our internal records. Please then delete the original email. Thank you. (Sent by Webgate1)
Re: Is it bad to make one zlinux running on 2 z/vm?
Yikes! Yes - it's very bad... You really need to investigate CSE (shared directory, shared RACF, XLINK protection) if you're going to share directory entries like that. Otherwise - NOLOG them on the side they should not come up on - and only undo that when you want to switch - and then NOLOG the other side. (or RACF REVOKE is another way). As far as using the same IP - well it is very hard to believe they were both accessible .. so maybe no one was looking ;-) Scott On Fri, Jul 24, 2009 at 4:19 PM, sunny...@wcb.ab.ca wrote: We sometimes accidently turn on one linux guest on two z/VM systems. Both z/VM system has their own DIRMAINT and RACF. No RSCS. We add the same guest direct file to two z/VM so it makes the flexibility to boot. Is it bad to make one zlinux running on 2 z/vm? So far we didn't get any complaint. But I can't expain myself how. It has same ip address and the same dasds. sunny -- This message is intended only for the addressee. It may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately so that we may correct our internal records. Please then delete the original email. Thank you. (Sent by Webgate1)
Re: Is it bad to make one zlinux running on 2 z/vm?
I would say you don’t want that to happen. You could get unpredictable results. We run some REXX code in the PROFILE EXEC that does a PING to see if the IP address is live. If the PING works we do a LOGOFF. We also, in the same REXX code, read a shared control file that list all guest and which lpar is the normal lpar for the guest. If it’s not the normal lpar we stop and ask do you really want to do this. Paul Feller AIT Mainframe Technical Support From: The IBM z/VM Operating System [mailto:ib...@listserv.uark.edu] On Behalf Of sunny...@wcb.ab.ca Sent: Friday, July 24, 2009 5:20 PM To: IBMVM@LISTSERV.UARK.EDU Subject: Is it bad to make one zlinux running on 2 z/vm? We sometimes accidently turn on one linux guest on two z/VM systems. Both z/VM system has their own DIRMAINT and RACF. No RSCS. We add the same guest direct file to two z/VM so it makes the flexibility to boot. Is it bad to make one zlinux running on 2 z/vm? So far we didn't get any complaint. But I can't expain myself how. It has same ip address and the same dasds. sunny This message is intended only for the addressee. It may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately so that we may correct our internal records. Please then delete the original email. Thank you. (Sent by Webgate1)
Re: Is it bad to make one zlinux running on 2 z/vm?
On 7/24/09 6:19 PM, sunny...@wcb.ab.ca sunny...@wcb.ab.ca wrote: We sometimes accidently turn on one linux guest on two z/VM systems. Bad, BAD idea. If they are in separate systems and the disks are shared R/W, then they will corrupt each other, and probably damage both to the point of being completely unusable. Duplicate IP addresses are a bad idea, as the network will end up very confused about which one is actually in control of the IP address at a given time. If you want this to work, then you need to configure CSE in your VM installation so that CP enforces that a user can be logged in on only one system at a time. You'll need RSCS (or an equivalent NJE implementation) and PVM to make this completely safe.
