Is the ’Write back’ option safe with at BBU Raid Controller?

[X1M]

I have a Server running with a PERC H700 Raid controller with 512MB NV RAM. I notice that under Proxmox VE 2.0beta there is now an option where you can select ‘Write back’ under Hard Disk.

I tried both option ‘none’ and ‘Write back, the IO performance was much better with the ‘Write back’ option.

Will this option be safe enough to use for production use, running with the above PERC H700 controller?
(I know that Proxmox 2.0 is still in Beta.)

 

[tom]

how did you benchmark? are you sure that you get really better IO performance or did you just measure the cache. I suggest everybody to use cache=none unless you have strong arguments for other setttings.

 

[X1M]

Thank you for your reply, I will use the ’cache=none’ for production use, when Proxmox 2.0 comes out of Beta. This is for a Zimbra mail server.

I did not use any fancy benchmarking tools, I just used cp to copy 10x600 Mb ISO files. Compressed them all into one file and then cp that.
In the beginning the performance different was around double but after around 2GB the performance fall down to what ‘cache=none’ would give. Even though it may have used the cache, the performance different was still there.

Since normal program use don’t copy that many MB at one time the performance different would make an impact.