Best ZFS SSDs?

[BaDaBooM]

Looking at adding a pair of SSDs (mirrored) for my zfs write cache (zil log) and also one for my read cache (l2arc). The read cache SSD seems pretty straight forward to pick out. Basically faster reads is better so probably any Vertex 3, Crucial, etc. would work well. However the write cache SSD is tougher to decide.

Basically with the write cache, I have read you want good write performance but don't need much capacity (because it only caches about 10 seconds of writes before flushing to disk). A supercapcitor or array of normal capacitors for power protection is a must though for no data loss. They say SLC is preferred instead of MLC, but couldn't you get an MLC and overprovision by 50% (since you don't really need more than 20 GB) to get the same reliability? Here is what I have been looking at:

You have Intel's 320 series which has the capacitor array but is only SATA II - I really want SATA III as I spent the extra for it on my motherboard.

OCZ's Synapse looked kind of promising and has SATA III but then doesn't mention anything about power protection.

I know there are Enterprise class SSDs that would meet the requirements but they are big on the $$$ and I have over buy capacity. Does anyone know of either and SLC or an MLC (that could be overprovisioned) with power protection and good write speeds for a more reasonable price?

Thanks in advance!

 

[lsv]

How much do you think you'll be writing to the write cache SSD? If it's a lot you'll need an SLC drive. If you're thinking it'll be a bit less you may be ok with a reliable MLC drive.

I wouldn't get anything but Intel for something like that :\

 

[Silenus]

Looking at adding a pair of SSDs (mirrored) for my zfs write cache (zil log) and also one for my read cache (l2arc). The read cache SSD seems pretty straight forward to pick out. Basically faster reads is better so probably any Vertex 3, Crucial, etc. would work well. However the write cache SSD is tougher to decide.

Basically with the write cache, I have read you want good write performance but don't need much capacity (because it only caches about 10 seconds of writes before flushing to disk). A supercapcitor or array of normal capacitors for power protection is a must though for no data loss. They say SLC is preferred instead of MLC, but couldn't you get an MLC and overprovision by 50% (since you don't really need more than 20 GB) to get the same reliability? Here is what I have been looking at:

You have Intel's 320 series which has the capacitor array but is only SATA II - I really want SATA III as I spent the extra for it on my motherboard.

OCZ's Synapse looked kind of promising and has SATA III but then doesn't mention anything about power protection.

I know there are Enterprise class SSDs that would meet the requirements but they are big on the $$$ and I have over buy capacity. Does anyone know of either and SLC or an MLC (that could be overprovisioned) with power protection and good write speeds for a more reasonable price?

Thanks in advance!

I think it comes down to how and where you will use it and the workload you will run. Is it a simple home setup, not super mission critical? I think the Intel 320's are perfect for a ZIL. With supercaps and lots overprovisioning I wouldn't worry about wearing them any time soon. And the 320 are not slow on the writes either...in some cases actually faster than Intel 710 series drives. SATA II vs III won't matter at all for ZIL since it is only going to help with small random and sync writes in particular...and you'll never come close to even SATA II speeds in that regard.

The read cache can be any single drive since failure here hardly matters except to slow you down for a while. Possibly SATA III would be good on the L2ARC, but only if you are connecting to the rig with something faster than a gigabit connection.

 

[BaDaBooM]

Well it is a home/small business set up, however as part of my goal with this set up is high availability so reliability is very important and I may be running up to 50 VMs on it with a few databases as well.

I am probably misinterpreting the specs but when I look at the Intel 320, for an 80 GB drive it only 90 MB/s sustained write and 10k iops random writes. That doesn't sound like it would be better than the 8 spindles that will be behind it and seems to pale in comparison to some of the other numbers I see for SSDs - or am I wrong on that?

I've been looking to try to compare to others but so far I have not found any SSDs that list the capacitor power protection outside of the Intel 320. Is that the only one in the couple hundred dollar range?

 

[lsv]

Well it is a home/small business set up, however as part of my goal with this set up is high availability so reliability is very important and I may be running up to 50 VMs on it with a few databases as well.

I am probably misinterpreting the specs but when I look at the Intel 320, for an 80 GB drive it only 90 MB/s sustained write and 10k iops random writes. That doesn't sound like it would be better than the 8 spindles that will be behind it and seems to pale in comparison to some of the other numbers I see for SSDs - or am I wrong on that?

I've been looking to try to compare to others but so far I have not found any SSDs that list the capacitor power protection outside of the Intel 320. Is that the only one in the couple hundred dollar range?

Have you considered an OCZ Revodrive? They're stupid fast. But I bet not very reliable.

 

[BaDaBooM]

Revodrive looks interesting for the read cache as it would not eat up a HD slot - thanks for the tip. Obviously not for the zil log since it has no power protection.