On Thu, Jun 17, 2004 at 08:02:59AM -0400, Greg Troxel wrote:
> Instead, it says, if a backup is level 0, can it be buffered on
> the holding disk. If the reserve parameter is set to 100, then
> 100% of the holding disk space can be used only for incrementals.
> All level 0's will go straight to tape. If the reserve is set to
> 25%, then that portion can only be used to buffer incrementals
> while the other 75% of the holding disk can be used for either
> level 0's or incrementals as needed.
>
> $(prefix)/share/amanda/WHATS.NEW says that this applies only in
> degraded mode. Before I put in 'reserve 50' I was seeing level 0s on
> holding disk, but amanda would not _start_ any level 0s if the tape
> was missing or had failed.
Are you sure that the amount of holding disk space you have,
minus 50%, is sufficient to hold those level 0's?
The whats."NEW" is actually quite old. Note at the top of the
document it indicates these are "new" as of version 2.3 and about
40% of the way through the version 2.2 document is appended.
The section you quote later is from that appended section and
is, I believe, misleading.
The primary change I'd make in the language as it applies to this
this discussion is in this section:
If there is no tape present (or the tape drive fails during dumping),
Amanda switches to degraded mode. In degraded mode, level-0 dumps
are not allowed.
I would add the need to consider the amount of unreserved holding
disk space to the definition of degraded mode. Something like:
If a DLE is scheduled for a level-0 dump it is backed up in
degraded mode if there is no tape present (or the tape drive
fails during dumping) and there is insufficient unreserved
holding disk space to store the entire anticipated level-0 dump.
Note, I think (uncertaintly level high) that this decision is made
on a DLE by DLE basis, not on an amdump run by amdump run basis.
My personal experience is that level-0's quite happily get done
with my reserve of 30 percent and no tape present. In fact,
due to a sloppy, lazy admin, the tape magazine has not been
switched for 2 weeks and last night there were still many level-0
dumps done to the holding disk. The reason this works is that there
is still lots of holding disk space available.
--
Jon H. LaBadie jon AT jgcomp DOT com
JG Computing
4455 Province Line Road (609) 252-0159
Princeton, NJ 08540-4322 (609) 683-7220 (fax)
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