2 Raid arrays, SSD and Raptor - striple size recommendations

FredBasset · 31 Mar 2010 at 08:11

I'm just putting the finishing touches to a new machine, its one of OCUK's 4.2Ghz bundles with a 5970 and will be used purely for iRacing.

I'm going to have a raid setup of 2 Intel 40Gb value SSD's in RAID (following the Anandtech article yesterday as 99% of the time I'll be doing reads on this machine) for Win7 and the application to increase load times.

This app also saves replay and some other information and I'm going to use the 2 150Gb Raptors for this.

Its been a while since I setup Raid, what stripe size would people recommend for each of these arrays.

Fred

Ziggy4 · 31 Mar 2010 at 15:10

For OS a strip size of 32 or 64K should do the job. For a secondary drive 128K works well in most situations, but not sure exactly what this mystery app is that allegedly increases load times (of what...most folks aim to decrease loading times) and stores replay data on this drive is so it might be worth experimenting with different strip size. Given the Raptors are going to be used for storage of sorts it's not a big deal to re-bulid the array if you decide to use a different strip size.

FredBasset · 31 Mar 2010 at 15:29

Cheers Ziggy4, its no mystery app, its name is at the end of the first sentence :-)

I meant to speed up the load times of the app!

Thanks again I'll try these values

Fred

Ziggy4 · 31 Mar 2010 at 16:07

I meant to speed up the load times of the app!

Gotcha! Having the Raptors share some of the burden should help. Not familiar with iRacing but sounds like you are able to record the race or select events on the second HDD? Sounds cool.

FredBasset · 31 Mar 2010 at 16:36

Yes replays and setups go to my docs, so I can just use win7's facility to direct the default save onto the raptors.

www.iracing.com, if you like driving sims its pretty cool with laser scanned tracks. Mostly US bias but Silverstone, Brands are there with Oulton coming soon. Sorry for the off-topic.

Fred

FredBasset · 2 Apr 2010 at 00:32

Ok with the two value drives in raid I got the following in Crystal Disk Mark

Seq Read 374.4, Write 86.27
512k Read 303.9, Write 87.37
4k Read 23.13, Write 71.46
4kQD32 Read, 213.7, Write 85.73

Do these numbers look ok?

Cheers
Fred

Ziggy4 · 2 Apr 2010 at 12:21

Reads look very good and higher than I had with paired Raptors. Can't remember right now what my write speeds were. Unfortunately I sold my Raptors and replaced with an SSD but I'll see if I have any old benchmark logs kicking around. What controller you running these on? Off hand, I seem to recall my reads were around 250 MB/s and writes around 120 MB/s or so. That was with 64k strip size on Intel ICH10R onboard.

Ziggy4 · 2 Apr 2010 at 12:28

OK I have some recent benchmarks of a VelociRaptor on same system. The striped Raptors were faster of course so looks like your reads are slower than expected but it will vary depending on what controller, driver, and strip size you are using. Can't argue with those blistering reads though. Bloody Hell!

Sequential Read : 105.188 MB/s
Sequential Write : 109.897 MB/s
Random Read 512KB : 48.889 MB/s
Random Write 512KB : 78.892 MB/s
Random Read 4KB : 1.024 MB/s
Random Write 4KB : 2.871 MB/s

I'll ask the friend I sold my Raptors to if he can run some benchmarks on them and I'll post them up when I get a chance. He's striping them on an Adaptec Host RAID controller card but it will give you a rough comparison.

Ziggy4 · 3 Apr 2010 at 22:57

Those numbers I mentioned have just come in. 2x Raptor RAID0 on Adaptec Host RAID.

Sequential Read : 139.392 MB/s
Sequential Write : 162.595 MB/s
Random Read 512KB : 51.875 MB/s
Random Write 512KB : 123.567 MB/s
Random Read 4KB : 0.903 MB/s
Random Write 4KB : 3.179 MB/s

Like I said it'll vary depending on the setup but don't think there's much wrong with your array.

roachyuk · 4 Apr 2010 at 00:00

i am using 128kb for the os drive is this the wrong size i am using then...should i use a smaller stripe size?

Stelly · 4 Apr 2010 at 00:47

I have always used 64k, but you will find arguements for all over the internet, I always thought that 128k was a little big, but some people say that they dont notice a performance benefit unless its 128k.... swings and round abouts

Stelly

Ziggy4 · 4 Apr 2010 at 03:11

I think 64k is as good a number as any if you are unsure or can't be bothered messing around and rebuilding arrays in order to find the best strip size. I've found the 128k to be slightly better for secondary volumes but we're talking about miniscule differences in practice anyway.

Arcane · 4 Apr 2010 at 12:44

I've got my array set to 128k, simply because OCZ recommended 128k for stripe size on their forum.