SAN vs Local Backup | SQL Server Performance Forums

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SAN vs Local Backup

I’ve read that local backups are much faster than backups on SAN, but on one of my systems we host the data on the SAN and I noticed backing up from the SAN to the SAN is still slower than backing up from the SAN to the C: drive. Why is this? I’m also curious as to what means I can use for copying the backup from the C: drive back to the SAN.

Are you asking about automation of copying backups from one location to another? Satya
Check the SAN configuration for concurrency, block size, segment size and disk agent buffer information. Also refer to KBAhttp://support.microsoft.com/kb/907418/ for more information. Satya SKJ
Microsoft SQL Server MVP
Contributing Editor & Forums Moderator
http://www.SQL-Server-Performance.Com
This posting is provided AS IS with no rights for the sake of knowledge sharing.
When you are testing backup throughput do not test with small dbs, it will give accuratin info to compare… Check the disk activity while backup was running on local as well as SAN.
You might have data and log files on SAN drives… reading and writing from location…
Mohammed U.
it all depends on how you configure your disks and controllers
its possible to get a very wide range of numbers, upto 1.5GB/sec or more Local is not inherently faster than SAN,
but can be on a per physical disk basis, and definitely on a per dollar,
so with SAN its really about how much you value the other features
The database that was causing time issues has a 35GB backup file. It takes about an hour to backup to SAN from the SAN while to the local disk it takes about 10 minutes. I think that knowledge base article linked by Satya could be what’s going on. If it’s only transferring in 64KB blocks then it would be expected to take a long time. I’ll be doing some SQL Server updates in January so maybe I can run some tests on this then to see how it’s performing. I am also curious about automation of copying backups from one location to another just for future reference if that’s an alternative I might have to take. I had previously read the following article which made me consider doing the local backup to begin with: http://www.sql-server-performance.com/backup_restore_tuning.asp I was especially focussed on
quote:For fastest backups, perform a disk backup to a local drive array (ideally, to an array dedicated to backups only), then move the backup file(s) over the network to another server where the file can be stored, or to a tape device. Backing up a database directly to tape on a local device, or to a tape device over the network, or to directly to a hard disk over the network, is generally slower. As a rule of thumb, I keep one copy of my database backups on the local server (even though they have been moved off the server to tape) as a convenience should I need to restore the backup quickly.

Currently the procedure we use is the following: Have backups go to C: drive which is SCSI RAID array (not sure of exact configuration but it’s fast).
Backup Exec gets all the backups from that specified backup folder and copies to tape. Seems to also go very fast. However a few problems are presented by this setup. Number 1 being that the C drive is relatively small while I have plenty of space I can use on the SAN for storage. I probably could con my boss into getting another array of disk drives for the server but I want to be very sure about this method before I ask him to spend money.
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