SSD RAID 0 array - stripe size and Trim question

[Tyler Durden]

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.

 

[Durzel]

I went with 128Kb stripe for 2 Samsung 840 Pros in RAID 0.

Remember with RAID you'll need to check whether TRIM is working manually. I recommend trimcheck

I thought I was a bit of a nutter sticking two of them in RAID, but you're gonna do 4 with a £400 RAID card? Kudos!

 

[Tyler Durden]

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...

 

[Subliminal Aura]

I went with 128Kb stripe for 2 Samsung 840 Pros in RAID 0.

Remember with RAID you'll need to check whether TRIM is working manually. I recommend trimcheck

I thought I was a bit of a nutter sticking two of them in RAID, but you're gonna do 4 with a £400 RAID card? Kudos!

^ Solid advice - I'm also on 128k

BTW Here's something I recently spec'd

YOUR BASKET
2 x Gigabyte GeForce GTX 780 3072MB GDDR5 PCI-Express Graphics Card (GV-N780D5-3GD-B) £569.99 (£949.98)
1 x Crucial M500 960GB SATA 6Gb/s Solid State Hard Drive - (CT960M500SSD1) £487.99
1 x Intel Core i7-3930K 3.20GHz (Sandybridge-E) Socket LGA2011 Processor - Retail £479.99
1 x LSI MegaRAID SAS 9266-4i SGL Controller Card - (OEM) RAID £382.99
1 x Asus Rampage IV Extreme Intel X79 (Socket 2011) DDR3 Motherboard £364.99
4 x Samsung 256GB SSD 840 PRO SATA 6Gb/s Basic - (MZ-7PD256BW) £189.95 (£759.80)
1 x Seasonic 1000w '80 Plus Platinum' Modular Power Supply £189.95
4 x Corsair Dominator PLATINUM 16GB (2x8GB) DDR3 PC3-15000C9 1866MHz Dual Channel Kit with DHX Pro Connector (CMD16GX3M2A1866C9) £169.99 (£679.96)
1 x Xigmatek Elysium Full Tower Case - Black/Silver £129.95
1 x NZXT KRAKEN X60 AIO Water Cooling Unit - 280mm (Socket 775 / 1150 / 1155 / 1156 / 1366 / 2011 / AMD AM2 / AM3 / AM3+ / FM1) £119.99
Total : £4,755.80 (includes shipping : £16.85).

 

[Tyler Durden]

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.

 

[Subliminal Aura]

Hi Tyler,

Yes .... That was just in my cart so I thought I'd dump it - I think my first preference was with an Areca controller(ocuk don't stock them) but I've got to look into that in detail also.

Many thanks for the heads up

 

[Tyler Durden]

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...