ADSM-L

Re: [ADSM-L] mediawait during backup to disk

2010-04-30 11:44:54
Subject: Re: [ADSM-L] mediawait during backup to disk
From: "Nast, Jeff P." <JNast AT SMDC DOT ORG>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Fri, 30 Apr 2010 10:43:42 -0500
Check out the "Maximum Size Threshold" that is defined for the disk pool
in question. Perhaps you are trying to back up a file larger than the
threshold and now TSM needs to mount a tape to handle that file...

-Jeff Nast
SMDC Health Systems
Duluth MN
 

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT vm.marist DOT edu] On Behalf Of
John D. Schneider
Sent: Friday, April 30, 2010 10:33 AM
To: ADSM-L AT vm.marist DOT edu
Subject: Re: mediawait during backup to disk

Keith,
   You could mitigate this somewhat by creating more disk storage pool
volumes, and spreading them across more physical disks.

   I don't entirely agree with Allen that your disk pool is going to be
slower than your incoming networks.  It is certainly possible to build a
disk storage pool environment that can respond that fast.  However, you
have to decide whether it is worth spending any money to do so.  How
close are you to running outside your backup window?  If you are getting
all your backups done in a timely manner, then the actual speed doesn't
matter.  But if you are pressing your window, you might have
justification for some engineering improvements.

Best Regards,

John D. Schneider
The Computer Coaching Community, LLC
Office: (314) 635-5424 / Toll Free: (866) 796-9226
Cell: (314) 750-8721



-------- Original Message --------
Subject: Re: [ADSM-L] mediawait during backup to disk
From: "Allen S. Rout" <asr AT UFL DOT EDU>
Date: Fri, April 30, 2010 10:14 am
To: ADSM-L AT VM.MARIST DOT EDU

>> On Fri, 30 Apr 2010 11:07:35 -0400, Keith Arbogast
<warbogas AT INDIANA DOT EDU> said:

> What does it mean when a node incurs mediawait during a backup to
> disk?

It means that the process was blocking on disk writes.

Your disk (usually) can't write as fast as your various networks can
pass you data. So there's some fraction of media wait, on a fine
granularity.


- Allen S. Rout


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