Hi all,

I'd like to have your point of view or experience regarding write cache activation (or not) in a SSD context.

In our case : 2 SC8000 wtth 3 tiers (SSD SLC -  SAS 15K - SAS 7K)

In a recommended profile, the Storage Center documentation advises to disable write cache, argumenting that write IOs will occur on SSD and latency on SSD is comparable to NVRAM latency.

Ok... so we made a simple test : 1 Windows 2008 R2 server with 2 LUNs in recommended profile. 

We simply copy/paste a big file (8Go) from the first LUN to the second LUN (the second is write cache disabled).

We notice that the copy operation is just 30% to 40% longer than with cache enable....  

So what ?

We tried with another server (Windows 2003) --> same thing.

We tried with other NTFS cluster block size --> same thing.

We tried to modify HBA Queue depth --> same thing...

So, for the moment, I don't disable write cache, even for SSD LUN...

Any idea or similar experience ?

Thanks.