L2ARC SOHO usage ...despite performance?

[mka]

Hello,

after reading the forum and guides, I've learned that I probably won't need an L2ARC SSD for my SOHO and Ram is always better.

But... what about persistence of the cache? My FreeNAS Server is powered down almost every night and powered up on demand in the late afternoon every other day. I've noticed the FreeNAS samba performance is quite slow after it's initial boot up... directory access times take a long time a first, but getting dramatically better in the first hour.

My explanation is: at every boot-up ZFS is trying to fill its volatile cache. After some time most accesses can be filled from cache and after shutdown ZFS has to start from scratch.

Whould an SSD configured as L2ARC help in this scenario cause it's persistence storage and non-volatile keep their cached date between shutdowns? Or wouldn't it be filled at all cause there is enough ram available? Or can this be adjusted?

Thank you!

 

[titan_rw]

L2ARC is not persistent. It's just an extension of the ARC, so it is lost on reboot.

One of the reasons to simply let freenas run 24/7. It's cache is very effective over the long term. But it needs a history to figure out what to cache where.

If you absolutely need to shutdown freenas, one could experiment with 'priming' the cache on startup with a startup script of running something like "find /mnt/tank > /dev/null" or something similar.

 

[mka]

L2ARC is not persistent. It's just an extension of the ARC, so it is lost on reboot.

Okay... there goes L2ARC :)

One of the reasons to simply let freenas run 24/7. It's cache is very effective over the long term. But it needs a history to figure out what to cache where.

If you absolutely need to shutdown freenas, one could experiment with 'priming' the cache on startup with a startup script of running something like "find /mnt/tank > /dev/null" or something similar.

ATM letting the server run 24/7 is not an option. I've already added an Startup and Cron job script "ls -alR /mnt/tank > dev/null".

It does speed things up but only half the way. I guess because most folders include media files with metadata (Videos, Pictures, Music) which the windows explorer reads while browsing but aren't touch by the "ls -alR" cmd and so not moved to the ARC.