From my understanding, tape drives are not supported by predictive. Went round and round about this with HP (actually regarding a SureStore jukebox, but also tape drives). Their reasoning - tapes are temporary media, so they don't want to report errors on them. I guess their logic is who cares about the mechanics of the drive itself.
As far as the DLTs (either 4000 or 7000) we use them here and like them VERY much. Of course the tapes cost 3-4 times what 125m DDS-3 tapes were costing, but much more reliable. Have only had one be marked as bad in my initial 1200 tape library.
Only problem as I see it, is that they don't restore as fast as they write. Supposedly, HP released a patch that would take care of that problem on labeled tapes, but since we don't use labeled tapes on our backups, I haven't tested it. Not terribly worried about it. One of the other support people here did a restore of a single file from a DLT7000 backup. Backup took 1 1/2 hours to store (few thousand files), and 1 1/2 hours to restore single file. Since we only do a small amount of restores, it isn't a problem. The reliablity of the tapes is more than worth it.
-------------------------------
Gary L. Paveza, Jr.
Technical Support Specialist
All opinions are mine and not those of my employer
-----Original Message-----
From: Chris Bartram [SMTP:[log in to unmask]]
Sent: Tuesday, June 22, 1999 11:46 AM
To: [log in to unmask]
Subject: DDS3 horror story...
We recently had a DDS3 tape drive go bad on us.. That's no big deal however;
with two 1537s (DDS3s) on our main system, we've replaced one twice and the
other once already in the past 8 months. What was truly scary was how we
found OUT about it.
Of course, predictive is no help. Never as much as a warning EVER related to
the tape drives. Not once on any of the failures we've seen.
WE have two DDS3 units on our main system; we always use brand new 125M DDS3
tapes. Backups are split (by volsets) between the two tapes. When the first
one finishes, we take the tape out, put it in the OTHER drive, and VSTORE the
entire tape. This has worked well (so we thought) so far.. It is what told us
we were having tape problems on the previous three occasions. (It seems a
commom occurance on DDS tapes to get just-enough-out-of-synch that a tape
might read/write it's own tapes with no problem, but another unit -which IS
in specs- will gag on the tapes written by the out-of-synch unit.)
Anyway; all was well. All tapes backed up without errors and validated on the
second drive without error. Not a SINGLE error. No warnings. Nada.
THEN it comes time to RESTORE some files from the tapes.
POOF.
X.Y.Z NOT RESTORED: MEDIA READ ERROR ENCOUNTERED ON BACKUP
Over and over and over. 4 tape sets. 5...and still counting. Well over a
month of backups. I have $stdlists from some of the VSTOREs. Did I mention
there were ABSOLUTELY no errors or warnings? On one database with 87 files,
52 failed to restore. Pretty worthless that eh?
My only guess is that actually restoring the files causes enough pause-for-
disk-writes that the tape ends up backing-up alot (where just reading the
data from tape into the bit-bucket didn't excercise the drive mechanism as
much?).
In any case, we're NOT happy. We're also not enthusiastic about DDS drives
(or perhaps I should say LESS enthuisiastic than we were before).
Using TurboStore/iX "True Online" 7x24 and HP C1537s. Vstore on same system.
About 111,000 files on the backup. Tape drive in question has since been
replaced.
Restores attempted (and failed) on same system as well as another 3000 with a
1537.
Not sure if the failure is entirely in the hardware, or if VSTORE has a
fundamental problem. Have an open HPRC call, but difficult for them to tell
anything since the bad tape unit(?) is gone...
Had been considering DLT7000s, but kept hearing about patches that weren't
available or not quite right? Since we're using TurboStore, we need (complete)
support in FOS. Anyone know if that's 100% yet?
-Chris "What backups?" Bartram