ADSM-L

Re: Slow backupset restore, a cry for help

2004-08-17 14:41:59
Subject: Re: Slow backupset restore, a cry for help
From: Matthew Glanville <matthew.glanville AT KODAK DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Tue, 17 Aug 2004 14:41:58 -0400
> The problem lies within the server side, since it does send the data to
the client very
slowly (and from the task manager I can see that the tsm server process
is reading data slowly as hell).

Wont that speed you see will just adjust itself to what the client can
write to the disk?
Most of the performance problems I have seen can be tracked down to network
problems or disk write speed problems caused by anti-virus software or
software raid, be sure you take care of them first.
Test the writing to that disk and TCP transfer rates by using somthing
else, ftp for instance, just to be sure it is or is not TSM client/server
issue.

> There are lots of small files, but could that be the problem ?

Yes, from my experience the more individual files you have the longer
everything takes, regardless of the amount of data.  It isn't necesarily
TSM, but the underlying file system.  Logging will slow it down a bit more
too.  Even the layout of the files in the directory can have an effect, are
there 10 million in one directory?  I've seen that before it ain't pretty.

So just how many files are there?

> How can I find out what the bottleneck is ?

  Keep looking, at more than just I/O speeds.  memory use is another place
things can slow down, is there alot of memory paging/swapping to disk going
on?  Lots of performance problems can be tracked down to this issue.

>As I have mentioned before - speed of generating backupset, regular
>backups and regular restores is normal (10-15MB/s) for an LTO drive.

This is why I believe the problem has to do with somthing on the TSM client
side and what it is doing.  Thats the one thing that's being introduced in
the equation when restoring a backup set.

> Frustrating.

This probably means the answer is somthing simple.

Hey, are you recovering the backup set using the GUI and a dialup link
through a remote access tool?  This can slow down restorations too...  use
the command line at all times unless on the console.  Even then, command
line is slightly quicker.

Matt G.

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