ADSM-L

Re: [ADSM-L] How to perform Readtest in TSM ??

2011-03-12 23:26:14
Subject: Re: [ADSM-L] How to perform Readtest in TSM ??
From: Nick Laflamme <dplaflamme AT GMAIL DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Sat, 12 Mar 2011 22:24:55 -0600
On Mar 12, 2011, at 9:42 PM, somu321 wrote:

> Hi All
> 
> Previously in our setup we used to take manual backup and do the read test of 
> tapes for a particular backup. But after migrating to TSM we are not getting 
> the idea for how to perform the readtest of aparticular backup. Please help.
> 
> -Somu321

There's no reason to believe, let alone any guarantee, that the data from "a 
particular backup" will be on any specific set of tapes. 

Backup data is often written to a storage pool of type DISK. From there, it's 
usually moved to tape or disk storage array of type FILE by the MIGRATE STG 
command -- and how that's done depends largely on the collocation policy of the 
storage pool the data is being migrated to. There's no guarantee that all of 
the data will be migrated out of the DISK pool; that depends on how long you 
let the migration process run and what you specify as the LO target. For data 
from a client who had a small backup session, it might linger in the initial 
DISK pool past several migrations that never got to the point of migrating all 
of the data out of the DISK pool. (That's not the most likely scenario, but 
it's plausible.)

My question for you is, what problem are you really trying to solve? 

AUDIT VOLUME will validate the contents of a sequential volume, such as a tape. 

If you're trying to assure yourself that all of a client's data is readable, 
perhaps you want to create a backup set for that client; that will force TSM to 
read all of that client's tapes and write them to new media. Alternately, Q 
NODEDATA will tell which tapes you care about, and you can AUDIT VOL them. MOVE 
NODEDATA would also force a process to read all of a node's data and write it 
out elsewhere.

If you use BACKUP STGPOOL to copy your sequential media to a second storage 
pool, that will force TSM to read all of the tapes you've recently created or 
appended to; that will assure you the media is readable and valid. (You are 
using BACKUP STGPOOL, aren't you? If not, what's your solution if a storage 
pool volume is destroyed by accident or malfunction?)

And it's possible your concern isn't covered by any of these techniques, and 
the solution for your problem will be entirely different, but it almost surely 
has a solution, once we get a good problem statement. 

Remember that some files on a node may not be on any backup taken in the last 6 
months, for example, because it was backed up nine months ago and hasn't 
changed since then. How does that factor into your question? 

Nick
<Prev in Thread] Current Thread [Next in Thread>