ARCserve 12 Slow Throughput 2

[ensignandrew]

Hello all,

I'm running into an issue where I'm getting slow throughput when backing up our backup server to tape.

Here's some background info:

- We're trying to backup about 7.3 TB
- Average throughput is about 450 MB/min
- Server is running Windows Server 2003 SP2
- Backup software is ARCserve 12 SP1
- Server is connected to the RAID array with a 3 Gb/s link
- Server is connected to the tape library with a 4 Gb/s fibre link
- Tape drives are LTO 4 and can run about 114 MB/s

I have already updated the drivers & firmware of the RAID and fibre adapters, the tape library, and the tape drives. I also recreated the backup job in case the original was corrupt. The job seems to start with decent speed (around 1,500 to 2,000 MB/min) and will be up around 3 TB complete the following morning, but when I check again the next day, the throughput will be down around 400 MB/min and the amount of files completed will only be about 100 GB. It's almost like it's getting halfway and then some part of the job is restarting.

I have a second job running that backs up our other physical servers. That one completes with an average throughput of between 1,200 MB/min to 1,500 MB/min even though it's going over the network.

I have a case open with CA, but I was hoping someone here might be able to throw out suggestions as to what could be causing the slowdown or what I might try to speed things up.

Thanks
Andrew

 

[davidmichel]

in general multiplex must be used in order to get the throughput of an LTO4.
3 to 3.5gb/m is a good normal throughput for that type of setup.
By the way if you have 1 4gb link to the library and 4 LTO4 drives running at a time it is way overloaded.
Get the SAN Admin to enable logging at the switch and then run the job to see if there is a high error count on either port.
Does the HBA share IRQ with anything else?
Try moving the HBA to a different slot.
Perhaps Windows Performance Monitor will help identify a bottleneck on the windows side.

 

[digex]

I'd check all of the above. Also what does the file structure look like? We have found that the more smaller files with deeper file structure puts a strain on the backup speed. Set the priority of the backup to "High" also. If you want to utilize your san fiber you can get the SAN Option and backup around 7,000-8,000 mb/m.

I would also check if you are using the Agent. WE have also found that bypassing the agent is sometimes alot faster in backup's and restores, but sometimes connetions drop. We have the biggest issues with the Agent's more than anything especially when backing up across the Ethernet Network.

 

[ensignandrew]

Thanks for the suggestions guys.

We are using multiplex and only have 2 LTO drives so I wouldn't think the 4 Gb link would be overloaded.

The HBA is sharing an IRQ with another device though, so I'll change it's slot to try and get rid of that conflict.

We are backing up a large amount of small files. I was thinking of zipping these before the backup runs to see if fewer larger files backs up faster then the large amount of small files.

Bypassing the agent is something I'd like to try, but I can't find where I would do this. Can you point me in the direction of where I would make that change?

Thanks

 

[davidmichel]

In most systems it is possible to change the IRQ by moving the card to a different slot.

Not sure if you can backup a remote system without the client agent, other than using Preferred Shares.

I'm guessing some testing has been done to verify the throughput of the RAID is not a bottleneck.

Check the virus detection program to see if it is scanning files being read.

 

[ensignandrew]

The server I'm trying to backup is connected directly to the tape library via fibre. That's why I was wondering if it was possible to bypass the agent.

Even though it's a local server, ARCserve sees it like every other server - shows up in the Source tab under Windows Systems (along with every other server) and properties show it using the UNC server name, not anything like 'localhost'.

 

[davidmichel]

ARCserve would have to be installed on the computer and the backup run from that computer in order for the data to go via the Fibre to the tape drive. In this case the SAN Option has to be used to enable sharing of the tape library.