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Large windows 2008 guest VM backup problems

AlGon
Level 6

Hello,

Netbackup 7.1 Windows OS

We’ve got a large Windows 2008 VM acting as a file server.

It’s been given a single CPU and 4GB of RAM.

Its’ got 3 drives assigned to it.

The server is configured to access the ISCSI storage directly, by using an ISCSI initiator inside the guest VM.  Therefore, snapshotting this server and doing a VM off-host backup is out of the question. 

Anyway, I’m looking into the possibility of doing a SAN level snapshot and presenting the snapshot to the media server.  However, due to the structure of the data on the server and the amount of small files, I think there will still be an issue with performance when backing it up.

Currently the Netbackup client is installed inside the VM and the backup is running at about 7MB\sec, so it’s taking way too long to complete – I’m pretty sure this is due to how fast the data can be pulled from the disk.  The problem is, that it fails a lot of the time just before it completes, with a 156 snapshot error (this is very frustrating).

I was thinking to place the server in a separate policy and turn multistreaming on.  This way if one drive fails with a snapshot error then at least the other drives have a chance to complete. 

Also, I think I’d get better overall read performance backing up all three disks at once due to the fact the each disk is on a separate LUN.  However, I can’t really do this because running multiple streams kills the CPU.

Am I right in saying that if I add more CPUs (this won't please the VM team) to this server then bpbkar will use one CPU core for each stream? 

Any other tips on improving the performance of this would be most welcome :)

Many thanks

2 REPLIES 2

Anonymous
Not applicable

Anyway, I’m looking into the possibility of doing a SAN level snapshot and presenting the snapshot to the media server.  However, due to the structure of the data on the server and the amount of small files, I think there will still be an issue with performance when backing it up.

I can tell you now that the backup performance we got recently on a Windows file server was astonishing:

We had the client inside the VM and was backing it up to one tape drive over the network - gigabit.

The server has 1.8million files and took 12 -14 hours to do FULL backup the file system which was 640GB of data stored (the main file data disk had compression turned on).

We converted that VM's backup to the NetBackup for VMware method

And now doing Mapped Full VM backup using SAN snapshots of the same VM we get the backup done in 2.5 hours, backing up 512GB. (FYI: Fibre channel SAN)

So my advice is setup SAN snapshots and dont worry about millions of small files as they are mapped.

We even backup a file server with 9.7million files (yoinks!) using the snapshot method.

pikachu
Level 6
Employee Certified

... that's the entire idea behind flashbackup. It reads in the raw device chunk and maps it out on the fly.