Adding SSD for l2arc cache

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Adding SSD for l2arc cache

Postby t3hite » Wed Dec 14, 2022 7:56 pm

I'm running a 4-bay drive enclosure with WD 6TB NAS drives (5640 rpm). I have a spare 500GB SSD that I could use as a read cache. Would it be any help?

I've seen how to add the disk to the pool. Do I need to make any changes to ARC memory settings?
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Re: Adding SSD for l2arc cache

Postby lundman » Thu Dec 15, 2022 1:56 am

Just add it as a l2arc - no reason to tweak arc settings for a l2arc
zpool add pool l2arc /dev/diskX
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Re: Adding SSD for l2arc cache

Postby t3hite » Thu Dec 15, 2022 10:02 am

How is that different from:
zpool add pool cache /dev/diskX
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Re: Adding SSD for l2arc cache

Postby Jimbo » Thu Dec 15, 2022 11:46 pm

I think the difference will be that "cache" should work, where as "l2arc" will have zpool going "err what?". :)
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Re: Adding SSD for l2arc cache

Postby lundman » Fri Dec 16, 2022 11:26 pm

dang it, i really should take the time to double check my commands :)
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Re: Adding SSD for l2arc cache

Postby t3hite » Sat Dec 17, 2022 9:21 am

I created the l2arc cache disk using: zpool add ''pool' cache 'dev'. I wasn't working till I changed the secondary cache property on the dataset to 'all'. Now it works but doesn't seem to be getting may hits.
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Re: Adding SSD for l2arc cache

Postby ffk » Tue Dec 20, 2022 8:43 am

From what I've read about L2ARC... the not getting many hits is how it works.

Will/does the addition of L2ARC help speed up directory listings? I have a few folders that have 500+ folders in them and it takes a while for them to list.
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