Disk Configuration: SSDs in RAID 0 with multiple partitions?

[Simon]

Hi All

I all but hit the order button on my build when Darren in Sales strongly advised against putting my 2*480GB SSDs in RAID 0 and then partitioning them, as apparently this has been known to cause failures because "the system gets confused".
This gives me a bit of a problem, because a very large, very fast drive is the main reason I'm changing from my HP DV7-1055EA to Vortex III.
My data is really stored on my desktop which has 3TB of data and 12GB of backup disk. So, other than the OS, just about everything on my laptop is actually in the offline files cache. I must be the world's biggest use of this feature of Windows!
So, I wish to have my laptop with a 175GB partition for the OS and programs, a 75GB partition for anything that might need to be on my laptop outside of the offline files cache and the remainder (ca. 710GB) in a third partition dedicated to offline files caching. You can move the offline files cache, but it can only exist in one place (i.e. on one volume).
I can't span the SSDs as Windows won't boot from a dynamic disk, so had figured out that firmware RAID 0 looked like a good way to go and there doesn't seem to be any technical reason why this configuration shouldn't work.
Yes, I thought about an mSATA SSD for the boot drive, but they're half as fast as the Intel 520 series and very small.
Oh, and I have read that TRIM is not YET supported for SSDs in RAID 0 - is this still true?

So - is this really a problem and if so, is there anything that can be done about it? Other than wait for a 1TB SSD, that is ...

Thanks for any help.

Simon

Chassis & Display
Vortex Series:17.3" AUO Matte Full HD LED Widescreen (1920x1080) (£85)
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Intel® Core™i7 Quad Core Mobile Extreme i7-3940XM (3.00GHz) 8MB
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16GB KINGSTON HYPER-X GENESIS 1600MHz SODIMM DDR3 (4 x 4GB)
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NVIDIA® GeForce® GTX 675M - 2.0GB DDR5 Video RAM - DirectX® 11
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480GB INTEL® 520 SERIES SSD, SATA 6 Gb/s (upto 550MB/sR | 520MB/sW)
2nd Hard Disk
480GB INTEL® 520 SERIES SSD, SATA 6 Gb/s (upto 550MB/sR | 520MB/sW)
RAID
RAID 0 (STRIPED VOLUME - 2 x same size & model HDD / SSD) (£9)
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SONY BD-5750H 6x BLURAY WRITER & CYBERLINK SOFTWARE
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Genuine Windows 7 Ultimate 64 Bit w/SP1 - inc DVD & Licence
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Antec Notebook Cooler 200 + Antec Big Boy 200mm Dual Speed Fan (£52)
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1

 

[Smurfette]

Having 2 SSDs in RAID 0 configuration isn't going to make any significant difference speedwise, and if one drive fails, you'll lose all the data anyway. At least RAID 1 mirroring would keep the data safe in case of drive failure. However... TRIM is not currently supported in RAID configuration, so it would be a waste either way.

What people generally do is use the SSD for their most used programs, then have a fast HDD (such as the Scorpio Black) as the second drive for data storage. Not only will it be cheaper, but it is far more practical and a whole lot less risky than RAID 0 striping.

 

[Simon]

Well, that does make me think again. I wasn't after a significant performance boost, but might have expected a small gain. The requirement is to have a larger SSD than 480GB. However, an SSD without TRIM support is not something I could live with. I wonder whether TRIM support for SSDs in RAID 0 will be something that can be implemented via firmware updates, in which case I might go with a purchase of 2 SSDs but wait for the TRIM support before I convert them to RAID 0. Any thoughts on that one, Smurfette (or others)? Thanks for your helpful post.

 

[Smurfette]

Intel has said that it will include TRIM support from version 11.5 of its Rapid Storage Technology, so if you can wait for that, you may be in luck.
http://downloadcenter.intel.com/Detail_Desc.aspx?ProductID=2101&DwnldID=21730&lang=eng&iid=dc_rss

That said, you may not even need to bother with RAIDing 2 SSDs together. The main performance increase comes with accessing massive files, so if that is what you do on a regular basis, you will notice the difference. For smaller files, the speed increase would be so negligible as to be unnoticeable.

Also, as far as I know, it is possible to relocate folders for your Offline Files Cache (in Windows 7). You can move it to a network location, or to another drive on your machine, but it may require some registry changes.

 

[Simon]

Thanks again, Smurfette.

I'm not too concerned with trying to increase the speed of the SSD, but I would like to have a 710GB SSD.

You are correct that a registry change will re-locate the offline files cache. But it can only be on one volume, so if you want to offline more than 480GB (and I might) then you have to have a drive that big. And if you do offline that amount of data then the synchronisation can become a lengthy process, hence me wanting to have a local, extremely fast and large disk with a fast wireless card.

Yes, I can wait for RST 11.5 BUT I've read that this support will need a Series 7 MB. I'm not sure what the MB is inside a Vortex III (some model of Clevo/Sagem, but I'm not sure which) and even if I did know, I'm not sure whether it is Series 7. By the way, I'm assuming that the Vortex III does support SATA AHCI mode?

Simon

 

[Smurfette]

Yes, the Vortex III uses the HM77 Express Chipset, which is Series 7. With that you get USB 3 and AHCI.

 

[Simon]

OK, Smurfette, that's a +rep.
I'll re-configure to RAID 0 once RST 11.5 is available. 480GB gives me enough space right now.
Thanks so much for your very helpful and expert advice.

Simon

 

[Simon]

Well, iRST 11.6 is now out and as far as I can see there is no mention of TRIM. I think I might have purchased an expensive SSD for nothing :-(

 

[Simon]

Probably the last word (from me) on the matter, so here goes ...

I posed this question to Intel Support, and have the following definitive replies:

"I am sorry but TRIM doesn’t work when you set SATA in RAID mode for any of our Intel® chipsets, including the HM77. TRIM gets enabled as soon as you set SATA in IDE or AHCI, if using Windows 7. Perhaps it will be supported in the future, but for now, TRIM doesn’t work with RAID. "

And when pressed as to whether iRST could be configured with the SSDs in AHCI mode (now or in the announced future):

"TRIM is not supported in RAID right now and there isn’t an announcement (at the moment) to be supported in the future. "

So, for the forseeable future the message is clear. DO NOT ATTEMPT TO IMPLEMENT RAID0 ON A LAPTOP WITH AN SSD unless you are prepared to live without TRIM (I wouldn't recommend that).