Any benefits from using a SSD?

[nogi]

I have a spare Crucial 128Gb SSD and was wondering if there is any benefit of using with my current FreeNAS setup? I’m currently running 4 x 3TB Hitachi 7K3000 in RAIDZ on a HP N36L Microserver. I have a spare SATA port which is for the ODD and possibly limited to 1.5Gbps (3.0Gbps if it isn’t).

 

[Milhouse]

Possibly as an ARC cache, though the rule of thumb is to size the ARC cache twice as large as your storage (ie. most of your 128GB SSD will be wasted), and to mirror the ARC cache for redundancy. An ARC cache could help speed up transfers to the N36L. You will need to install the hacked Russian BIOS for the N36L which enabled full speed SATA on the ODD (or something like that).

I've been toying with the idea of getting a pair of cheap-ish 32GB-40GB SSDs for ARC cache duties in my N36L (with 8-port LSI 9211 controller and 8 disks - 4x3.5" + 4x2.5" - connected, and the internal 4-port SATA entirely unused). Not because I need them, just because I can... :)

 

[Joshua Parker Ruehlig]

Possibly as an ARC cache, though the rule of thumb is to size the ARC cache twice as large as your storage (ie. most of your 128GB SSD will be wasted), and to mirror the ARC cache for redundancy. An ARC cache could help speed up transfers to the N36L. You will need to install the hacked Russian BIOS for the N36L which enabled full speed SATA on the ODD (or something like that).

I've been toying with the idea of getting a pair of cheap-ish 32GB-40GB SSDs for ARC cache duties in my N36L (with 8-port LSI 9211 controller and 8 disks - 4x3.5" + 4x2.5" - connected, and the internal 4-port SATA entirely unused). Not because I need them, just because I can... :)

You can't have ARC cache on an SSD, your'e thinking of L2ARC. ARC resides in memory.

Also there is pretty much no benefit in mirroring your ARC / L2ARC, you may be thinking of using an SSD as a ZIL. Where mirroring is recommended, especially for zpools before version 19 as a loss of the ZIL means the zpool is lost (not the case for zpools made/upgraded on FreeNAS 8.3).

 

[Milhouse]

Sorry, yes, L2ARC... and maybe it was a ZIL!

It's late, and I last looked at this a while ago! ;-)

 

[nogi]

Thanks guys.