On Tue, Jul 7, 2020 at 9:05 AM Joe Monk <joemon...@gmail.com> wrote: > Most ORGs are abandoning RAID-5 in favor of better like RAID-6. Any DASD > array should be engineered with two hot spares and call home service to the > vendor for drive replacement. >
I agree. But our z/OS DASD is a very old 2105(?) which I doubt implements RAID-6. We have, and still are, going away very soon (10+ years so far) so management doesn't consider it reasonable to invest any money in any z/OS related hardware or software (we're z/OS 1.12 on a z9BC) > Joe > > On Tue, Jul 7, 2020 at 8:58 AM John McKown <john.archie.mck...@gmail.com> > wrote: > > > On Tue, Jul 7, 2020 at 8:19 AM Jackson, Rob <rwjack...@firsthorizon.com> > > wrote: > > > > > Fun little note on RAID: it is fallible. The last Sunday of October > > 2016 > > > I got a call bright and early because our VTS (TS7740) had shut down. > > > Turns out we had a "cache" HDD failure at around 4 AM, and then a > second > > > one failed at around 7 AM, before the first one had been rebuilt on a > > > spare. RAID-5 could not accommodate it. Because of IBM politics, we > had > > > no tape until Monday at 16:00. I am ashamed to say that I sort of took > > > tape for granted. It was astonishing how much of our processing > depended > > > on it. > > > > > > > We had a similar problem occurs, long ago, with an actual SAN dasd array > > (for Windows, not MVS). Weekend backup to physical tape aborted on a > > Sunday. The Windows admin said "No problem, it's a RAID-5 array, I can > fix > > it Monday morning." A few hours later, a disk in the array failed. No > > problem, right? Unfortunately, while the CE was on his way in to replace > > it, a second disk failed. The array was destroyed. Management said to > > repair it and reload from the Sunday backup and we'd be good. When the > > admin admitted that the backup failed and he didn't go in, he was > > immediately terminated. Now, what are the chances that 2 drives in an > array > > will fail within hours? I don't know, but one thing many don't think > about > > with a "new array" is that all the drives are likely the same age and > will > > start to fail (if they are) about the same time. > > > > IMO, given my paranoia, I firmly believe that the disks in an array > should > > be replaced on a scheduled basis. I also believe in dual tape copies of > > important tapes. And also, that tapes in "long term" retention (we have > > tapes which have been at Iron Mountain for over 10 years!) should be > > brought in and the data copied to a new (not reused) tape annually. Of > > course, the bean counters will have an apoplectic fit and scream about > how > > much it costs to do this. They only understand cost, not value. I > consider > > them the bane of existence. Likely auditors, they take on too much > > authority. Or as I have heard: Fire is a good servant but a terrible > > master. > > > > > > > > > > > > R.S. is spot on: make backups. Because of the trauma from this one > > > event, we now have a three-way VTS grid, synchronous-mirrored SANs, and > > two > > > mainframes on the floor. > > > > > > First Horizon Bank > > > Mainframe Technical Support > > > > > > > > -- > > People in sleeping bags are the soft tacos of the bear world. > > Maranatha! <>< > > John McKown > > > > ---------------------------------------------------------------------- > > 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 > -- People in sleeping bags are the soft tacos of the bear world. Maranatha! <>< John McKown ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
