On 01/21/2012 04:06 PM, retired mainframer wrote:
If the entire volume is unreadable, it would seem you need to use DELVOL to
tell SMS that everything that was supposed to be on that volume is lost.
If some of the files on the tape are usable, then FREEVOL may be a better
choice or possibly RECYCLE (either combined with the appropriate BDELETEs to
skip over the unreadable files).
AUDIT does not process the media. It processes the various CDSs and
catalogs to ensure consistency but not necessarily accuracy.
As with all datasets, anything of which you have only one copy that is
unreadable means you have zero copies.
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of af dc
Sent: Saturday, January 21, 2012 11:29 AM
To: [email protected]
Subject: DFHSM: Backup tape lost due to errors
Hello,
suppose you have an 3592-JB dfhsm cart (native, not a vts stacked
cart) that can't be read due to physical damage, no tape backup
duplication. Several backups are unique, no additional versions. How
to correct bcds ?? Run AUDIT DATASETCONTROLS (BACKUP) with NOFIX (to
check the amount corrections) and then with FIX ??? Z/Os V1.12.??
I've said it before, but will say it again: modern tape media has such
a large capacity that a single dfhsm cartridge can contain an incredibly
large number of datasets. It is almost inevitable that loss of a single
dfhsm ML2 or Backup cartridge will impact something you care about or
can't afford to lose (or are legally required to retain), and it is also
inevitable that single cartridges will occasionally be physically
damaged. Over the long haul, you really can't afford NOT to duplex all
dfhsm carts (and for that matter, non-dfhsm carts that contain data you
can't afford to lose).
All it should take is the potential loss of one critical, irreplaceable
dataset to justify to management the cost of the extra cartridges and
tape drives required. Tape duplexing in some form with off-site storage
is also a requirement for any reasonable installation Disaster Recovery
plan, so it ought to be cost-justified on those grounds alone, with a
side benefit that DR duplex copies can also save your backside from
single media disasters. If management lacks the wisdom to support
duplexing, file the recommendation away and bring it back out when the
next inevitable media failure and massive data set loss occurs.
The duplex support in dfhsm makes duplexing ML2 and BACKUP carts
trivially easy to do as long as you have enough drives. Similar support
should also be available in software/hardware solutions that stack
multiple non-dfhsm virtual volumes on physical volumes (e.g., CA-VTape),
where similar exposures exist and where duplexing in some form is also
highly recommended.
--
Joel C. Ewing, Bentonville, AR [email protected]
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