When using a Dell PowerVault MD1200 DAS SAS storage array as a repository destination on Windows server with vRanger installed on the same server (or a remote server) the performance is poor 1-2MB sec.
The same backup run to the local C: drive on the same server runs at 30-70MB sec.
This is cause beuase the defualt write caching policy on the Dell PERC RAID controller connecting to the PowerVault MD1200 is set to "Write Through" by default.
***ENABLING RAID WRITE CACHING WITHOUT A PROPER BATTERY UPS ON A RAID CONTROLLED SERVER CAN RESULT IN DATA LOSS IN THE EVENT OF A POWER FAILURE. PLEASE ENSURE THE SERVER AND POWERVAULT MD1200 ARE PROTECTED BY A BATTERY BACKUP BEFORE ENABLING WRITE BACK CACHING***
In order to resolve this performance issue, the caching policy for the DAS mounted PowerVault RAID volume must be set to "Write Back"
1. Reboot the server to the BIOS POST Screen.
2. When the controller POST is displayed, press Ctrl+C to access the RAID controllers BIOS config.
3. If more than one RAID controller in system, select correct RAID controller that connects to the MD1200
4. Select the RAID volume from the list, and press enter to access the Advanced Properties of the RAID Volume.
5. Using your TAB key, tab to the Advanced Caching Policy, and use the space bar to enable the selections.
6. Using the TAB key, tab to the Write Cache Policy pull down and press enter.
7. Select "Write Back" as your caching option. (The defualt is "Write Through")
8. Use your TAB key to move to the OK button, and select OK.
9. Use escape to exit the RAID Controller bios screen, and press ctrl+atl+delete to reboot the server.
Once the server has rebooted, open Device Manger in Windows. Drill down on the disk drive item tree, and locate your MD1200 mounted volume and select it's properties.
Select the Policies tab, and ensure Write caching, and advanced write caching is enabled. If not, enable, and click OK to save.
Run backups as normal. Speed should increase dramtically.