fastest server backup

[Iain Hamilton_4]

I have 20 win 2k servers with a total disk space of 900 gig.
What would be the best way to back these up.
I am using arcserve on each server at the moment backig up to their own local tape drive.
I have evaluated Powerquest V2i protector.
But am still not sure about the speed.
V2i does 8gig per hour .
Ihave claims by tape manufacturers quoting 28gig per hour. Who do I believe.??

[Ian Dennison_1]

Iain,

It depends where your limiting factor is between the data and the tape drive.

The favourite of Tape Drive manufacturers is to talk about "compressed" throughputs, which is the best possible rate. Look for "native" transfer rates, which show uncompressed rates.

Remember, the Server has to process the IO from the drive to the tape, which takes CPU as well as Bus I/O. It may be that the drives cannot deliver the data quickly enough, or the CPU is flat out trying to a) process the IO and b) manage the Powerquest Application, not to mention c) continue handling normal processing for this server.

Do you have various configs on your Win2K servers that you can benchmark against each other to see which perform better? From this info, you can look at the differences and infer what the bottleneck is.

Share and Enjoy! Ian

[Leif Halvarsson_2]

Hi,
Backup performance is very much hardware dependent. If, for example, using LTO drives, connected local or via FC it is no problem to backup 100GB/h to each drive if there is no other performance bottlenecks (e.g cpu, disk/filesystem). Very important is the average filesize, don't expect high performance with millions of small files (if you don't use disk image backup).

Most of my experience is with OmniBack/Data Protector but, for raw performance I think the backup application is less important.

[Dave Dewar]

Iain,

What performance are you seeing at present?

A high end tape drive is rarely the limiting factor in performance terms. An Ultrium 460 will stream at 30MB/s native speed which is 108GB/hour. However, to acheive this it needs the rest of the system to keep up with it.

Below is a link to a HP perf troubleshooting guide that makes use of the performance tools we have provided. See the second link for the ools.

http://www.hp.com/cposupport/information_storage/support_doc/lpg50460.html

Use this to find out what you current systems are capable of first. This will then allow you to decide what you need to spend money on.

Cheers,

Dave Dewar.

[Christian Schwartz-Søre]

Another important factor to consider is that fact that performance comes from spindles. The more spindles you have, the faster the tape performance, but as mentioned earlier, there can be many bottlenecks in the system.

W2K is capable of handling app. 12MB/s per filesystem/volume which is another limiting factor.

If you can't keep your tapedrive streaming, because the tapedevice is too fast for your environment (LTO2), then you're much better of using a slower device capable of keeping up with your system (you avoid start-stop mode, tear and wear on the tapes and device), giving you better performance.

If you're using backup software capable of doing multistreaming, you can run up to 32 streams from the same or several servers simultaneously, achiving a high transfer rate, and faster writes to tape. That way you might even stream to an LTO2 at min. 10 MB/s or even more.

The trade off is restore wise, where there is an app. overhead of 25%, due to the fact that data is fracmented on the tape.

A good idea is to use PAT or another performance assesment tool to see what can be expected from your arrays in terms of read speed. Based on that you can decide which taoe device(s) to deploy.

regards
christian

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