SSD for ZFS (Should I?)

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tangoseal

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I know what an SSD for ZFS does as far as caching, well mostly, I understand it will typically help with read/writes etc... due to caching the L2-ARC.

SSD's are getting cheap. I was thinking of installing a 120GB SSD as a Cache drive.

Any thoughts.... do you, people that actually own and cache ZFS, think that they make a difference overall?

Thanks and Merry Christmas
 
there is no way to know if it will help you or not. It all depends on what you do, how large your working set is, how much ram you have.

Using an ssd for caching (l2arc) won't help write performance at all though.
 
So it will help with reads though? I have 32gb ram and over 10tb of storage. Mostly single user access or device access however my server is on a 10g network to my sig deaktop.
 
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tangoseal said:
So it will help with reads though? I have 32gb ram and over 10tb of storage. Mostly single user access or device access however my server is on a 10g network to my sig deaktop.
Click to expand...

You may check your current ARC efficiency (http://cuddletech.com/arc_summary ), but I suppose with single user usage most of your reads are already from ARC RAM. I doubt you will feel any difference.
 
It is only going to help, if the data you keep accessing is >32gigs and <150gigs. For a general purpose fileserver, very unlikely to help for a single user. If your storing vm's on it, it might help.

Thought for me, personally, I get about 92% arc hits, and the other 8% are split even between 100gig l2arc and disks, but given that 8% is only 30iops, I wouldn't be able to tell the difference between l2arc and no l2arc. I only put it in there cause I had it, and nothing better to do with it.
 
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