Veritas-bu

[Veritas-bu] Drive Cleaning, your opinion

2006-06-07 02:54:58
Subject: [Veritas-bu] Drive Cleaning, your opinion
From: bob944 at attglobal.net (bob944)
Date: Wed, 7 Jun 2006 02:54:58 -0400
> How does everyone clean their drives? Heir are to rules of thumb (It
> think). One for allowing netbackup to do tape drive cleanings and the
> other is to allow the hardware to clean itself when it needs it. What
> are the pros and cons in each of these ways?

There used to be a Veritas document that warned against letting the
robot clean the drive because of the non-trivial chance that the robot
would put a cleaning tape into the drive when NetBackup was in the
middle of changing tapes on a drive, downing it.  Might still be on the
site; haven't looked at it in years.

Cleaning cartridges (as opposed to old reel-to-reel head cleaning with
alcohol and swabs) are abrasive and destructive--that's how they work.
It's better to abrade the globs of dirt and oxide and binder from the
head than not, even though it means wearing the head out a bit.
Abrading the head without a need to remove junk from the head
accomplishes nothing except prematurely wearing he head, which will in
itself make the drive more and more error-prone.

My take on when to clean and what should do the work, in most- to
least-preferred order:

Cleaning triggers:
1.  TapeAlert (highly recommended, the software equivalent of the
cleaning light)
2.  Clean-me light (ugly but much better than 4)
3.  Syslog (or similar) error monitoring
4.  Time (wear the heads out if set too low, get errors if set too high)

Cleaning methods:
1.  NetBackup automatic, triggered by TapeAlert
2.  NetBackup manual (CLI or GUI) by operator, triggered by clean-me
light or error
3.  Robot automatic by TapeAlert or similar magic
4.  NetBackup CLI initiated by error monitoring
5.  Drive replacement after overzealous use of time-based cleaning ruins
the previous drive

Miscellany
NetBackup uses these terms for cleaning methods:
Reactive (TapeAlert)
Library-based
Frequency-based
Operator-initiated

The Media Manager Administrator's Guide's "Drive Cleaning" section is
the must-read section.

NetBackup 5.x releases sometimes miss TapeAlert, to be fixed in next MP:
http://support.veritas.com/docs/283223

Let ACS robots clean themselves:  http://support.veritas.com/docs/267306

You're on your own for NDMP-attached drives:
http://support.veritas.com/docs/269574

Libraries which handle the cleaning can result in status 204, "unable to
initialize robot" errors:  http://support.veritas.com/docs/283234