I'm curious about something...
In our previous 7.2 production installation, the "Idle device timeout"
library attributes were set to the default of 10 minutes, and that value
was kept through our 7.5.1 upgrade a few days ago.
The 7.5 admin guide states:
"Idle device timeout - The number of minutes before an idle device is
unmounted. This attribute only applies to SmartMedia, Silo, and shared
native jukeboxes with device sharing enabled."
Our old SCSI-attached Sun L100 libraries (Quantum M2500s, I believe) are
now unloading all tape drives automatically under 7.5.1. They never did
this under 7.2 with the same configuration.
Looking at the server properties (NMC, Configuration tab, Device
Management), 'Device sharing mode' is indeed set to 'maximal sharing'.
However, two other 7.5.1 environments, both with SCSI-attached libraries,
have the same setting and they don't unload the drives. *But* the other
two have the Idle Device Timeout set to zero.
All three environments are co-located (i.e., single-host) server & storage
node systems.
Based on what the 7.5 docs say, I wouldn't have thought that direct
attached libraries would be considered "shared", therefore disabling the
effect of the 'Idle Device Timeout' value. However, from what I'm seeing I
assume that setting 'Device sharing mode' to 'maximal sharing' apparently
qualifies them as "shared native jukeboxes", enabling the 'Idle Device
Timeout' value to take effect.
I'm not sure whether automatically unloading tapes is a good thing or not:
eg. having a tape in the drive available for writing vs. having the drive
open and available for (reading from) other tapes. I'm still undecided on
whether I want this behavior or not.
But, I'd like to know if setting the 'Idle Device Timeout' and/or 'Device
sharing mode' will control it even for direct-attached SCSI hardware on a
single server / node.
Any opinions ?
Thanks.
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