Brian, I dont take it personal, but like many experienced sysprogs, you might be developing tunnel vision for other very capable solutions. Your way works for you, so you can sleep at night. When I said zfs on the sysres, you misunderstood. I was speaking of the smpe zfs target datasets, not general user datasets so there is no chance someone will make a situation like you describe occur. As for better resiliency with 3 volumes vs one, thats also a false sense of security. How long will you stay running if one of them goes away? In my largest production sysplex, half the systems are on one sysres, the other half on another. This is only being done in case there is a human error of some sort vs an array failure.
________________________________ From: IBM Mainframe Discussion List <[email protected]> on behalf of Brian Westerman <[email protected]> Sent: Wednesday, July 23, 2025 1:44:05 AM To: [email protected] <[email protected]> Subject: Re: z/OS 3.1 upgrade - res volume CAUTION EXTERNAL EMAIL This message came from outside your organization. DO NOT open attachments or click on links from unknown senders or unexpected emails. Report Suspicious<https://us-phishalarm-ewt.proofpoint.com/EWT/v1/MwwqYLOC6b6whF7V!o_OKOf-orsBAsaQZzDjuV_w-p1zQNmAGzTQwz8dqpFdojlA5EOSeW0SD4xx2b3Pl0T17IUulwATxXlVtHdXNSlEXGABaDjIcJSpL2vJj6cUqpeRxsqKWGk6edg$> I agree that there may be no "right" answer, but there are an awful lot of wrong ones. Please don't take this as a criticism of the way you are set up, I'm sure it works fine for you. The problem I see with keeping everything on a single volume is that you are creating a single point of failure. Because of the sheer size of keeping everything on one pack you are extending both recovery and the necessary backups. The zfs datasets are too volatile (my opinion only) to be kept there. I know of sites that believe that they should keep their RES, DLB and USS stuff on the one volume. If it works for them, then I'm happy for them, but I would not do that. If it works for you, then I am very happy for you and wish you luck, but I would not be able to sleep well knowing that someone on the system programming staff can make a brain check error and ruin everyone's day. Or that an application programmer messes up and one of my zfs's is now 900,000,000 cylinders. :) I really should not comment like this, because I truly hate when people don't agree with me, but I didn't want to let the OP think that this was was acceptable, or simple, from a backup and recovery basis. Please don't take my comments badly. I'm just trying to give the OP a rule of thumb that will fit any site and be easy to maintain. Brian ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN 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 to [email protected] with the message: INFO IBM-MAIN
