Poor performance backing up to iSCSI target
I am seeing very poor performance backing up my Exchange server to iSCSI-based Backup-to-Disk. Here are my details:
Media Server Type: Virtual (ESX 4.1)
Operating System: Windows Server 2008 R2 Standard - fully updated
iSCSI Appliance: Dell MD-3000i
NIC Configuration: (2) VMXNet 3 - one on the LAN and one on the iSCSI (isolated) subnet
Backup Exec: 2010 R3 fully updated (Version 13.0 Rev. 5204 64bit)
Note: The Dell MPIO driver is installed and iSCSI is configured per Dell's recomendations for Server 2008 R2
Exchange to iSCSI B2D Speed: 550 MB/min
Exchange to C: B2D Speed: 1350 MB/min
Media Server to iSCSI B2D Speed: 1150 MB/min
Windows Explorer C: to iSCSI Speed: 3000 MB/min
In other words, if I back-up the Exchange server to the Backup-to-Disk folder on the iSCSI appliance I get less than half the throughput I get backing up to the C: Drive on the Media Server or backing-up the Media Server to iSCSI. If I do a straight file copy using Windows Explorer I get about 3000 MB/min. I'm not particularly impressed with 1 GB/min but I can work with that. 500 MB/min is painful for the size of our Exchange environment. I've searched the forum and the internet and I have found other people with similar problems but no solutions. Any ideas out there?
Symantec does not recommend the use of a virtual machine as a media server because you will have problems accessing real devices. See Colin Weaver's comment in this discussion regarding this as an alternative configuration