RAID 1 SSD drives with TRIM

[grolendaves]

I'm looking to setup a system with mirrored SSD drives, i'd like to have TRIM support, and I am finding conflicting information. Some articles say TRIM doesn't work with drives in RAID, some say it will work with a RAID controller but not with drives configured in a RAID set, and others say that it works with RAID but not RAID5 and doesn't go into detail beyond that.

So can I get a mirrored set of SSD's with TRIM support? What chipset? Does anyone have any experience with this? Thanks if you can help!

 

[sminlal]

I've never seen anything suggesting that the TRIM command is passed through to drives that are configured as members of a RAID volume.

What's confusing is that in order to use the "firmware RAID" that's supported by motherboard chipsets such as the Intel ICHxxR series, you have to configure the entire chipset to run in "RAID" mode. But that doesn't mean that every disk connected to the chipset has to be a RAID volume - you can still connect individual drives and run them as separate, non-RAID disks.

The latest Intel ICHxx drivers WILL pass TRIM commands to drives even if the chipset itself is configured in RAID mode - but they have to be individual, non-RAID drives. The intention is to support TRIM for a non-RAID OS volume while at the same time allowing RAID organizations for data volumes attached to the same chipset.

So to the best of my knowledge the statement that "TRIM can be used with the controller in RAID mode" is true, but the statement "TRIM can be used with disks organized as RAID sets" is not true.

 

[Zoomer602]

I too have wondered how to effectively use SSD drives in Raid 1. Since dependability is critical in my systems, we use raid 1 and daily backup (Ghost incrementals). Would LOVE to convert to SSD for speed (sata3) but cannot understand how anyone can do this. If I raid 1 a pair of SSD drives how do I do the garbage collecting? TRIM won't work, so in theory over time the drives will slow down. Is there another program or manual clean up that will keep the drives clean? Is RAID 1 just not yet possible for SSD without expectation of degradation of speed over time? Would love a solution and I would buy a paif of 256GB Intel SSD Sata III if there was one.

Any experts with some advice?

 

[sminlal]

IMHO the moral of the story is "don't use RAID with SSDs". You don't get all that much of a performance gain, and there are no moving parts to break, shock or wear out so redundancy shouldn't be as pressing a concern as it is for hard drives.

 

[Zoomer602]

sminal - then why when you read reviews you see so many failures with SSD'S?
If one fails I am tied to just the backups which usually is enough but then there is only one failsafe and of course hardware downtime. I know -I might just forgo RAID and hope I dont regret that decision.

 

[sminlal]

I strongly suspect that most problems with SSDs are "infant mortality" problems where the drive doesn't work out of the box, or are "firmware upgrade" problems where an upgrade goes wrong. Once an SSD is set up and working, there really isn't much to go wrong with it.

I chose an Intel drive because I believed it to be more robust, and this seems to be borne out: http://www.thinq.co.uk/2010/12/9/pc-component-failure-rates-documented/

Remember that you need a backup anyway, so all RAID really does is to avoid downtime in the event of a drive failure.

 

[Zoomer602]

I can appreciate your comment on Intel SSD, but the new series (SATA III) no longer uses an intel controller and it appears that the reliability advantage may narrow now. Plus, the more I think about it - if I am to skip RAID 1, why not purchase a PCI-E drive since it is SO much faster than any other type. The Revo2 is just SO fast and this is a new system that I will centering around whichever SSD I choose. I think OCV is the only PCI=E drives made right? Intel does not priduce one yet?

 

[nofun]

A simple workaround is to create a partition that only uses 80-90% of the SSD's total capacity. Even without Trim, the SSD's controller will use the overhead space for garbage collection.

 

[IntelEnthusiast]

Right now we product a Mini pci-e SSD in the Intel® SSD 310s. There are now there are some boards that are starting to come out with this port on them. Most of these boards are planning for the use in mini-ITX, HTPC or Kiosks but it is expanding into other board for things like SSD caching. At this time these are not designed for super high end performance.

On the Intel SSD 510 SATA III, we used a Marvell controller because we haven’t finished the testing and preparation of our own SATA III controller. So in order to fit the demand for a SATA III SSD we contracted with Marvell to provide us with a SATA III controller for the time being. I haven't heard of a reliability drop on these but the performance isn't as good as the Intel SATA II controller in the Intel SSD 320 and older X25-M drives.

Christian Wood
Intel Enthusiast Team