ADSM-L

Re: NetWare Backups (Length of Time)

1998-09-24 16:18:36
Subject: Re: NetWare Backups (Length of Time)
From: Russell Street <russells AT AUCKLAND.AC DOT NZ>
Date: Fri, 25 Sep 1998 08:18:36 +1200
Hi...

> Hello all, we have been having a problem with our NetWare 4.11 backups
> taking a tremendous amount of time to perform their nightly incrementals
> - 10 hours in some cases.

Try checking the ADSM database cache utilisation.

adsm> qu db f=d
...
                Cache Hit Pct.: 98.71

If that is significantly below 99% then you could get huge performance
hits --- we certianly did.  Increasing BUFPOOLSIZE in dsm.opt made the
backup run in reasonable time.


My explanation for why this hits Novell clients worse than anything
else is:

  - the novell client can only use small amounts of memory on the
    client system

  - so as it traverses the directory tree it queries the ADSM database
    for one directory at a time [UNIX clients read the ADSM database
    for the entire directory tree before traversing it.]

  - which means the ADSM server is going to the database disk for
    every directory.  Which is slow.

  - but with sufficent cache, the ADSM server must be doing read aheads.
    Or the ADSM server is asked about the same information over and
    over by the client and now we are caching it.


IBM have recently put a V3 performance tuning guide up on the web.  It
includes lots of ideas on Novell.


Russell
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