SSD RAID 0 array - stripe size and Trim question

Tyler Durden · 10 Jun 2013 at 23:51

Hi,

I am building a new system and plan to run four Samsung 840 PRO SSDs in a RAID 0 using an LSI MegaRAID 9271-4i controller.

I have two queries:

What stripe size would you recommend?
I realise that there is no "ideal" stripe size and that there is a balance to strike between larger stripe sizes for file transfers etc and smaller stripe sizes for small file writes/reads.
The drive will be my main OS drive, so I am thinking 128K...
Opinions much appreciated.

Secondly, I am wondering about enabling TRIM on the RAID array with the LSI card. I have no experience with TRIM, so I thought I would ask for advice.

Thanks.

Tyler Durden · 13 Jun 2013 at 23:14

Thanks for the reply.

I think I am going to go with 128K. It does seem a good balance.

Thanks for the link. Useful little programme.

From what I gather, hardware RAID does not seem to support TRIM at all, but over-provisioning renders it unnecessary.

Unfortunately, I have had to return my Samsung 840 Pros. It turns out (confirmed by LSI) that the 9271-4i controller has a compatibility issue with that particular SSD. They also made it clear that there were no plans to resolve this with a firmware fix. I have returned them and bought four Corsair Neutron GTX drives instead...

Tyler Durden · 13 Jun 2013 at 23:27

That is an awesome looking build you have there. Similar in some respects to the epic project I have been working on (and saving for) for a year...

One piece of advice, though. As I just discovered to my cost, the Samsung 840 Pros cause problems with the LSI MegaRAID controllers (from the 9260 to the 9271 from what I understand). Specifically, the disk cache policy is locked, disabling the SSD write cache and crippling performance. Worth bearing in mind.

Tyler Durden · 13 Jun 2013 at 23:40

No problem. I thought you may well have already seen my post, but just in case, it was worth repeating. So many posts, so easy to miss stuff.

Intriguing issue between LSI and Samsung's 840 Pro series. Even more strange that LSI are well aware of it, but fail to list the issue on their site as a warning, yet have no intention of resolving it...