On Thu, Mar 22, 2018 at 23:03:33 +0000, Ryan, Lyle (US) wrote:
> And one bonus question: I'm assuming Amanda will just make vtapes as
> necessary, but is there any guidance as to how many vtape slots I
> should create ahead of time? If my dumpcycle=14, maybe create 14
> slots just to make tapes easier to find?
Under v3.4, there are actually two separate "automatic" actions involved
in using a vtape for the first time:
The first is automatic creation of the slot subdirectories under the
chg-disk: root directory. This is controlled by properties set in the
changer definition within your amanda.conf, i.e.:
define changer my_vtapes {
tpchanger "chg-disk:/vtapes/TestBackup"
property "num-slot" "10"
property "auto-create-slot" "yes"
}
Since you are using a straight vtapes-on-a-single-giant-disk-that's-
always-mounted configuration, it make sense to let Amanda do the slot
creation that way rather than going through the process of creating them
manually.
(You can find more info on these properties in chg-disk section of the
amanda-changers man page.)
The other action is the initial creation of an Amanda label on the vtape
(i.e. the first time an particular vtape slot is used).
This is controlled by the "autolabel" option on the storage in question
(or as set by the global "autolabel"); see the amanda.conf man page for
more information on that parameter.
For example, I have these lines in the TestBackup config's amanda.conf file:
labelstr "^TESTBACKUP-[0-9][0-9]$" # label constraint regex: all tapes must
match
autolabel "TESTBACKUP-$2s" empty
The "$2s" causes the generated label to be the two-digit version of the
the slot number, so slot1 gets "TESTBACKUP-01", slot9 gets
"TESTBACKUP-09", slot10 gets "TESTBACKUP-10", etc. (So that serves the
purpose of making a particular volume "easy to find" in the vtapes
directory tree.)
(In this scenario I only expect to need autolabeling the very first
time a slot is used, so I restrict autolabeling to "empty" tapes only
to reduce the chances of having some actual data silently overwritten
someday later.)
So, if I have both these configured as described above, then when Amanda
goes to find a new tape to write to, if there aren't yet num-slot slot
directories out there, the chk-disk change will automatically create the
next one, then Amanda will see a blank tape and auto-label it with the
matching tape label, and then proceed to write data to this
"newly-assembled" volume.
Note that since your configuration has all your "tapes" under that
single chg-disk changer, you actually need to set "num-slots" (i.e. the
number of vtapes that you have) to some number greater than your
*tapecycle* setting. Tapecycle is the parameter that controls when
Amanda is willing to overwrite a previously-used volume, so you have to
have at least that many volumes in your rotation (and a few extra is
usually a good idea so there is are some spare tapes available).
(To put it another way, while dumpcycle certainly influences what you
choose for tapecycle [as discussed in earlier replies on this thread],
it's the tapecycle setting [plus some spares] that determines the number
of vtape slots you need...)
Nathan
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