Optimum Size for Primary Diskpool to cater daily backup size

tomriderss

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PREDATAR Control23

Hi all!

Im very new to TSM... hopefully somebody can help with my question...

We are backing up 50 TB of data everyday to TSM (DISK-primary pool --> tape-seconday pool).

I noticed when backup runs, sometimes it will go directly to tape instead of diskpool.

So i think most probably due to my primary pool that is too small (3TB).

Now we are backing up 50TB of data everyday.

And i just extend the diskpool to 15TB... will it be sufficient? how do i calculate the optimum size for primary disk pool?

Thank you so much!
 
PREDATAR Control23

Are you backing up 50TB daily or protecting 50TB daily? By that, I mean are you really backing up (transferring) 50TB daily, or is the incremental backup inspecting 50TB and backing up what changed in that 50TB (protecting)?

In either case, it would be good to see that number from the server statistics. Run this query to see how much data you are backing up daily by date:
select date(end_time),sum(bytes/1024/1024/1024/1024) as Size from summary_extended where activity='BACKUP' or activity='ARCHIVE' group by date(end_time) order by size desc

If you never want the backups to overflow to tape once the disk is full, the disk pool will need to be larger than the largest day. If you are ok for it to overflow sometimes, then pick a number closer to the average than the maximum.
 
PREDATAR Control23

Hello, tomriderss...

The answer from marclant is pretty well spot on but I'd be curious of one more thing:

What is the intention of your data flow?
... Are you ingesting data to disk and then backing up to a tape copypool in the context of DRM? Or,
... Are you ingesting data to disk and wanting it to overflow to a a tape primary storage pool?

If it is the former, then you'd want enough disk to hold all your protected data and enough tape (plus more) to hold all the backups of that data to go offsite.

If it is the later, then you'd have a finite amount of disk as marclant said just to hold your daily ingest capacity and then you'd use migration settings on your storage pool to control how and when it gets moved to tape.

So for an example, the configuration I'm currently supporting is...

~20TB of protected data with roughly ~2TB daily ingest rate.
33TB of disk space spanned across 13 drives with roughly 50% occupied (I use de-dupe).
50 LTO4 tapes for primary tape pool and drm copy pool.
... I have not exceeded the free hard drive space yet so nothing resides in the primary tape pool. but when disk is full, migration settings will start moving data to tape.
... All data from disk pool and tape pool (when it starts being used) is copied to another tape pool called drmtpool and taken off-site weekly.

migration doesn't run yet since disk isn't full but expiration and reclamation take care of all the basic maintenance for me.

Hope that helps.

-b
 
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