Re: [Veritas-bu] Understanding DSSU

2010-09-09 10:09:23
Subject: Re: [Veritas-bu] Understanding DSSU
From: Nate Sanders <sandersn AT dmotorworks DOT com>
To: Nic Solomons <Nic.Solomons AT attenda DOT net>
Date: Thu, 9 Sep 2010 09:09:13 -0500
 Yeah it sounds like disk pools may be the answer. The thing that has me
confused is that for 9 straight days before our 5.1MP6-->6.5.6 upgrade,
I had 0 failed jobs. I found two problems in two different policies that
were the cause of all previous DSSU troubles and as able to fix them. So
suddenly after no change but the NBU software version, we're seeing a
%35 increase in the number of failed jobs on DSSU.

On 09/07/2010 04:39 AM, Nic Solomons wrote:
> What you are describing is the same behaviour I see across my environments.
> Not aware of any functional modification that 'fixes' this, either...
> Once NB assigns a resource to a job, it will wait on that resources 
> availability. It does this for DSSUs, Tape heads, everything.
> i.e. as you are seeing, if a job is running against one DSSU, and that DSSU 
> goes full during the job, it will wait on cleanup processes, until timing 
> out. No spillover.
> Same with tape heads, if you have a job running against a tape head, and that 
> tape goes full, and the only other available media is running jobs in another 
> head, that job will never switch heads.
> I think someone mentioned disk pools, which would do what you want 
> (configured through volume manager, or using nbdevconfig at CLI) - but i'm 
> assuming you are using Basic Disk units currently, and Disk Pools are 
> Advanced Disk (which has an additional license cost associated).  Of course, 
> if you switch to advanced disk, it means you can use SLPs instead of DSSUs as 
> well...
> Additional/advanced functionality - theres always a cost :P
> Cheers,
> Nic
> -----Original Message-----
> From: veritas-bu-bounces AT mailman.eng.auburn DOT edu 
> [mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Nate 
> Sanders
> Sent: 03 September 2010 19:32
> To: Rusty.Major AT sungard DOT com
> Cc: Sanders, Nate; Veritas List; veritas-bu-bounces AT mailman.eng.auburn DOT 
> edu
> Subject: Re: [Veritas-bu] Understanding DSSU
> After checking all 6 DSSUs only one contained 6 images that were
> expired. This for sure does not explain why we continue seeing failed
> jobs, especially tiny failed jobs.
> So is my understanding of Storage Groups not correct? When one unit says
> its full, shouldn't the job proceed to the next unit in the group? This
> is certainly not the behavior we are seeing based on logs and errors.
> On 09/02/2010 02:43 PM, Rusty.Major AT sungard DOT com wrote:
>> I first did an ls -l and grabbed the image ID of the images I thought were 
>> too old and should have been destaged and expired off of the DSSU.
>> I then took those images and ran them through bpimagelist to see if they had 
>> a copy on tape (or if it should have been expired).
>> Those that had a copy on tape or should have been expired were bpexpdate'd.
>> If you aren't familiar with these commands, read up on them in the commands 
>> guide and do some practicing with them. Especially with bpexpdate.
>> Rusty Major, MCSE, BCFP, VCS ▪ Sr. Storage Engineer ▪ SunGard Availability 
>> Services ▪ 757 N. Eldridge Suite 200, Houston TX 77079 ▪ 281-584-4693
>> Keeping People and Information Connected® ▪
>> P Think before you print
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Nate Sanders            Digital Motorworks
System Administrator      (512) 692 - 1038

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