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.
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 -----Original Message----- From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of R.S. Sent: Tuesday, July 7, 2020 4:36 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Storage & tape question [External Email. Exercise caution when clicking links or opening attachments.] Yes, it is possible to have VTS without real tapes on backend. Some vendors do offer only "tapeless tapes", with no option to connect real tape library. However from OS point of view there is difference between disk (DASD) and tape (offline storage). Price difference is also worth to consider, however I mean the logic. Even the biggest, cheapest and really huge DASD will not protect you form human and application (and other) errors. But backup will do it. That's why we do backups. We don't afraid of disk failure, because we have RAID, spare modules and possibly remote copy. However we do backups. If you insist on DASD, you may (theoretically) connect another DASD box dedicated for backups only. And even (logically) disconnect it between backup sessions. However it is IMHO worse version of VTS. Note: I do not discuss here things like price (initial, per terabyte), compression, thruput, scalability, RAID, etc. -- Radoslaw Skorupka Lodz, Poland W dniu 06.07.2020 o 16:46, kekronbekron pisze: > Hmm... do a lot of shops use actual cart based tapes ... TS77xx with TS4x00? > Don't know if EMC DLm has a cart back-end option. > > If it's VTL with disk back-end, is that any different from having it all on > DASD? > > > - KB > > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ > On Monday, July 6, 2020 4:25 PM, R.S. <r.skoru...@bremultibank.com.pl> wrote: > >> I forgot something obvious for me: NEVER USE TAPES FOR APPLICATION DATA. >> No jobs should write or read tapes. >> Nothing except backup and restore and (optionally) ML2. Managed by >> HSM or FDR. Some excepions for archive copies are worth to consider. >> Note: you may have 15 years old backup on new shining tape. Migration >> from older tape is no nightmare at all. It is simple. >> >> --------------------------------------------------------------------- >> --------------------------------------------------------------------- >> --------------------------------------------------------------------- >> --------------------------------------------------------------------- >> --------------------------------------------------------------------- >> ------------------------ >> >> Radoslaw Skorupka >> Lodz, Poland >> >> W dniu 06.07.2020 o 12:49, R.S. pisze: >> >>> W dniu 05.07.2020 o 14:12, kekronbekron pisze: >>> >>>> Hello List, >>>> Just wondering ... assuming there's a primary storage product out >>>> there that can store how-many-ever hoo-haa-bytes, and is a good >>>> product in general, it should make sense to begin eliminating all >>>> tape (3490/3590) use right? >>>> First, ML1 & ML2 in HSM, then HSM itself, then rebuild jobs to >>>> write to disk, or do SMS/ACS updates to make it all disk reads/writes. >>>> Looking at the current storage solutions out there, this is >>>> possible, right? >>>> What would be the drawbacks (assume that primary storage is super >>>> cost-efficient, so there's no need to archive anything). >>> Few remarks: >>> Even the cheapest possible DASD will not replace backup and other >>> things (archive copy, etc.) I did replace 3490E tapes with really >>> cheap second hand DASD boxes, it was approx. 20 years ago. Been >>> There, done that. It wasn't very fine solution, it was cheap and >>> working. AFAIR HSM does not like DASD as the output for some >>> activities, can't remember details. >>> Someone wrote about tapes moved to DR shelter. That's very >>> old-fashioned. I would strongly prefer to have remote copy, that >>> means two dasd-boxes and connectivity between. >>> There are products for tape emulation on CKD disk. It is definitely >>> no cheap. It also consume MSU. >>> Tapes, even virtual tapes are OFFLINE media from MVS point of view. >>> Offline media are good for some oooops! mistakes. >>> Last, but not least: you assumption is far from reality. DASD is >>> still more expensive than tape. The more capacity the difference is bigger. >>> Tape (real one) is cheap when talking about carts and very well >>> scalable. However tape realm with "first cart" is extremely >>> expensive, because drives are expensive, controllers are expensive >>> and ATLs are expensive. >>> The real decision depends strongly on your capacity, your predicted >>> growths, your needs and budget. >> == >> >> ====================================================================== 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. 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