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Re: [Networker] Networker and autocleaning
2006-10-12 09:51:51
On Oct 12, 2006, at 6:50 AM — 10/12/06, Davina Treiber wrote:
Lars Hecking wrote:
If a tape library supports autocleaning, what are the recommended
settings
for it on the library and in networker? I guess it's more
important to have
it set in networker, will enabling it on the autoloader interfere?
Some pretty strange things were happening on my Superloader
yesterday. The
tape drive got cleaned during a backup, and the cleaning tape
remained in
the drive. After unloading it manually and restarting the backup,
the drive
got cleaned again a few hours after the backup finished. Then,
checking up on
the next backup last night, I found that the cleaning tape had
been moved to
the mail slot! (Superloader = new, cleaning tape = 3 uses).
You will see that not everyone agrees on this issue.
I believe that if your library supports cleaning, then you should
let the library do it.
NetWorker controlled cleaning in its original form is flawed
because it cleans based on a time interval. This goes against the
recommendation of most tape drive manufacturers who suggest that
you should clean a drive only when the drive requests it.
Current versions of NetWorker are able to read the clean request
signal from the drive using CDI and clean accordingly, and in some
ways that is the ideal scenario because it gives the user a view of
cleaning tape usage from the software. Without this you are relying
on checking cleaning tape usage from a library front panel or a web
GUI if available, this all depends on your hardware. However, many
users have experienced problems with CDI and decided to disable it.
Of course if the cleaning doesn't work well with your library then
you don't have so many choices.
One thing I have noticed is that if your backup schedule calls for
writing data to a tape for many hours on end (a high capacity tape)
and the tape drive signals that it needs to be cleaned early in the
writing process, problems can develop. This can give grief regardless
of if you allow NetWorker to do auto-cleaning or the tape library. I
have a few large NDMP clients that can spend 10 hours writing to a
single tape cartridge via NDMP and if the tape drive receiving the
data signals a need to be cleaned early (such as one hour into the
backup process), that means it will receive data for another ten
hours or so while the tape drive is complaining that it needs to be
cleaned.
This is the situation on the Sony PetaSite with S-AIT tape drives
that I manage. So, I have NetWorker 7.2.1 set up to auto clean those
drives every 2 days, but once a week, I manually clean those drives
via "nsrjb" and I keep 4 cleaning cartridges in the tape library (for
13 tape drives).
This arrangement works out very well.
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