Each recycle process only takes only 50% more drives: three instead of
two.
Unless it has recently changed, one annoying thing about DFHSM in a
tape-drive constrained environment is there is no easy way to put an
absolute upper bound on the maximum number of drives needed concurrently
by all DFHSM tasks. Yes, you can separately restrict the number of
daily backup tasks, daily ML2 movement tasks, and migration recall
tasks; but this doesn't really address the unpredictable concurrent
demand from asynchronous ML2 recall requests and demand backup requests
that may go directly to tape; and those requests can occur at
inconvenient times, like when ML2 migration, or auto-backup to tape, or
recycle is in progress. If you want to more-tightly restrict the total
number of drives used by unscheduled DFHSM tasks during scheduled tasks
with high drive demand, there is no easy way to do just that, and the
greater drive requirements with duplexing can make this more of an issue.
I would never use DFHSM with today's high-capacity cartridges without
duplexing, but in some environments duplexing may require adding
additional drives.
JC Ewing
On 02/26/2013 12:30 PM, Staller, Allan wrote:
1) be aware that duplexing for backup and migration are separate commands.
2) recycle, ml2 migration and volume backup will now take twice as many tape
drives as before. You may have to change the limits on
the number of backup tasks, migration tasks and recycle tasks you run
concurrently to fit within physical constraint (# of tape drives available).
3) Plan on a program of recycling all existing media to get them duplexed. You
can use tapecopy, but recycle will most likely be more efficient.
HTH,
<snip>
We are looking at implementing DUPLEXING for DFHSM. My question is, besides
the parms in ARCCMD9A which needs to be update are there other parms that need
to be modified?
</snip>
...
--
Joel C. Ewing, Bentonville, AR jcew...@acm.org
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