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Guidance on Striping two F240s


robbob4

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I currently own two Corsair F series F240 Solid State Drives and I have both of them connected to my LSI SAS Controller (listed in my computer specs as Hardrive 6). Both drives I have updated to firmware 2.0 and I have done a good bit of benchmarks comparing them with my with my onboard controller in AHCI mode. This computer if you couldn't tell already is going to be a gaming computer and I have games such as Arma 2 that perform better on a drive with a high amount of IOPS due to the large quantity of files being read every second during game play.

 

After secure erasing the drives, I can get up to 25,000 IOPS (on 512 byte random test) on the sas where only 17,000 IOPS onboard and up to 269MB/s on the sas where only 260MB/s on onboard using HDTunePro.

 

After putting the two drives in to a stripe array (which has a 64kb stripe size since the sas controller has no other option), aligning to 512kb and allocation at 64kb I get 20,000 IOPS and 346 MB/s.

 

I am largely concerned about TRIM not working correctly though in a stripe array because I did an array like this before, put windows on it and after two days I was down to 5,000 IOPS (however I had never secure erased the drives before).

 

1) Should I not stripe these SSDs in order to insure that I don't depreciate my performance from the loss of TRIM or is there an alternative to TRIM? 2) Also is it a bad idea to have windows on this array because I may need to update the firmware in the future as well as the increased use of having windows on the drives?

 

3) I will have my second HD103SJ in the mail soon (both were sent to me defective) and I plan on striping those as well. Would it be a better option to put windows on those instead of the SSD stripe?

 

4) Also I am curious if you guys think with a 64KB stripe that a 512KB align and a 64KB allocation are optimal.

 

Thanks!

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In regard to my fourth question, that topic does describe the best stripe size and allocation size but it does not describe the best alignment size for each configuration. So my fourth question still stands: Is a 64KB stripe that has 512KB align and a 64KB allocation optimal?

 

If you do not know what I mean by partition alignment, Google "how to align ssd with diskpar" and click the forum post "Guide Guide for Win Xp installation with Diskpar (alignment ..." I believe I cannot link you directly since it is on a competetors' SSD forum. But basically you use a program diskpar (there are also other methods I believe) and you hide X many sectors on the SSD to vastly improve performance since the drive can access the data easier in 4kb segments.

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What O.S. are you using and will this be the Boot drive?

Best performance will be with a 128K Raid stripe and 32K allocation on the format.

But if it will be the Boot drive the format allocation will need to be 4K.

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What O.S. are you using and will this be the Boot drive?

Best performance will be with a 128K Raid stripe and 32K allocation on the format.

But if it will be the Boot drive the format allocation will need to be 4K.

 

My os is also listed in my system specs but it is windows 7 pro x64. I am not sure if this will be the boot drive (it is one of my questions). I can either make the two ssds my boot drive in a raid array, select just one, or put it on two 7200rpm hdds in a raid.

 

Also I understand that a 128k raid stripe is optimal however I am forced to a 64kb stripe using my LSI SAS Host Bust controller; so my next best is 64kb stripe, with either 32kb or 4kb allocation depending on whether it is a boot drive but what about the alignment?

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My .02 for what it's worth - I'm content with the SSD Boot+HDD storage combo as it works for just about everything I can think of without causing agitation, consternation, wailing, and the grinding of teeth.

 

You can still RAID them if you feel like it though. If you're going with a 64k stripe, I'd suggest to go with a 16k allocation to keep the ratio at 4:1 which seems to be the "ideal" ratio according to RAID storage gurus. Unfortunately, I forgot my copy of "Zen and the Art of RAID" back at home so I can't tell you why exactly that is.

 

You can set up Win7 to boot off of it, but there is some trickery involved. NTLDR doesn't like allocation units above 4k but the OS doesn't mind it at all. I've got a post around here with the commands and everything all set up. If you're interested in giving it a go, I suggest you look for that post. Will save you a lot of headache. (Update - here's a link to the old thread)

 

Oh yes, on alignment - so long as you use Win7/Vista (to include their respective setup programs) to set up the disks they will already be aligned automatically.

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Windows Vista will not support SSD's like that and the format will need to be done prior to the install with Vista XP or 2000, only Windows 7 is optimized for SSD drives according to the information provided to us from Microsoft.
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