I am running Server 2012 Std, PowerEdge 2900 III, 16GB ram, multiple RAID 5 arrays w/ 10K SAS. Its an older server, but RAM is utilization is less than 50%, CPU is 8-12% (1 core flat out is 25%).
Windows Server backups to a 7.2K external sata disk have a throughput of just above 50MBps, 2 VMs. Not horribly slow, but less than half of what I see on a straight up file transfer to an identical external disk.
Is this a normal speed, or might there be somewhere I can optimize further?
Additional Info:
- Shadow Copy size limits are set to 1GB per volume on host, no previous versions. (When set to 10% of volume or no limit, the backups would stall out on larger volumes: after a period of time VM response would go to nil, host response extremely slow, noticed that shadow copy size on current volume was growing extremely large--70GB and counting on 1TB of data with essentially zero VM disk activity during the backup. The only way to recover was a hard reboot of the host or setting the shadow copy size to a small amount--presumably forcing the shadow copy to stop/error out.)
- Shadow Copy size limits on VMs are default, default previous versions.
- Backup performance on host set to Normal. I.E. Does not use shadow copy to track changes between backups.
- Backup selection is set to the default "full." So the VMs are selected to backup via child VSS, AND the host volumes containing the VHDX disk are selected.
As an aside, I read that if a host volume ONLY contains VHDX disks of VMs it does not need to be included in the host backup selection. Is that correct?
