Slow backups for Windows VM's compares to Linux VM's

[ken_nguyen]

Hello Everyone,

I am hoping that someone here have seen this issue or replicate this issue and possively provide a solution to my "problem".

Here are my senerios:

- BE 2015 FP3 (latest) on Windows 2008R2 Enterprise

- 10GB 9000MTU iSCSI backend into EMC SAN with multipath IO

- VMware ESXi 6u1 hosts

- vCenter applicance 6u1

- Backup transport mode is SAN

- VM's are all located on SAN

- Full VM backup

I've created 2 backup jobs, one for a Linux VM and one for a Windows VM.  They are both located on the same datastore and host and have very simlilar disk size.

Here is the problem:

- Linux backup job rate is about 5000-8000MB/m to tape and disk

- Windows backup job rate is 1500-2500MB/m to tape and disk

I've tried various settings and backup themods such as GRT/no GRT, AOF on and off MS VSS on and off, IPv4, latest backup agents and everything that I can think off but still no luck in figuring out why the Windows job is so much slower than the Linux job.

Doing some network monitoring, I've determined that during a the Linux  backup job, there isn't much communication going on between the BE server and the SAN.  Hower when doing the Windows backup job, there is a constant request from the BE server to the SAN for 512 blocks at time (blocks can be various but mostly 512)

Basically, the only difference between the Windows job and the Linux job is of course the OS.  And you wouldn't think that it matters to the BE server since it's backing up the blocks. 

Is BE 2015 treating Windows backup job different than Linux?

Any ideas, sugessions or educated guesses?

Thanks,

Ken

[Dee006]

Hi Ken,

1.Any network configuration mismatch(route,duplex,MTU) on windows machines?

2.Do you have any end-protection software running in those windows machine?Have you tried to disable and backup(Try it in non production server)

3.What disk controller used in the windows VM?

4.Any existing snapshot still presence in those VM?

[ken_nguyen]

Hi Dee006,

1.     All the Windows VM's are running on the same Datastores as the Linux VM's and are configure for 1000 MTU's on the iSCSI.

2.     I do have Symantec Endpoint Protection running on some of the Windows VM's.  Please note that the backup software does a snapshot for the VM then uses SAN Transport Mode to backup so the AV should not have matter.

3.     Most of the disks are using LSI Logic SAS

4.     No snapshots on VM's.

[Dee006]

Hi Ken,

Can you try to keep MTU 9000?