How I added a cache drive to an existing pool

[Stenull]

I couldn't find option for adding cach drive to an existing pool from GUI so i started thinking we must do it the hard way.
My setup is 4 drives in raidz1.
Build is FreeNAS-8.0.3-RELEASE_MULTIMEDIA-p1-x64

Ok here we go...

1.
Exported pool from GUI (Make sure u don't Mark the disks as new (destroy data) :)

2.
In CLI i could see that pool was still up

Code:

[Stenull@freenas] ~> zpool status
  pool: Tank1
 state: ONLINE
 scrub: none requested
config:

        NAME           STATE     READ WRITE CKSUM
        Tank1          ONLINE       0     0     0
          raidz1       ONLINE       0     0     0
            gpt/disk0  ONLINE       0     0     0
            ada2p2     ONLINE       0     0     0
            gpt/disk2  ONLINE       0     0     0
            gpt/disk3  ONLINE       0     0     0

3.
I found my new cache disk with

Code:

camcontrol devlist

4.
Added cache drive to pool with

Code:

zpool add Tank1 cache ada4

5.
Checked that it attached nicely

Code:

 [Stenull@freenas] ~> zpool status
  pool: Tank1
 state: ONLINE
 scrub: none requested
config:

        NAME           STATE     READ WRITE CKSUM
        Tank1          ONLINE       0     0     0
          raidz1       ONLINE       0     0     0
            gpt/disk0  ONLINE       0     0     0
            ada2p2     ONLINE       0     0     0
            gpt/disk2  ONLINE       0     0     0
            gpt/disk3  ONLINE       0     0     0
        cache
          ada4         ONLINE       0     0     0

6.
Exported pool

Code:

zpool -f export Tank1

7.
Auto import from GUI

And it's done...

 

[lrusak]

what did you use as a cache drive? 64GB SSD? did you notice any difference?

 

[Stenull]

Yes i used a 60GB SSD.
Haven't benchmarked it yet.
After i started transmission i thought my regular disks would benefit from a cache drive.

 

[lrusak]

Yes i used a 60GB SSD.
Haven't benchmarked it yet.
After i started transmission i thought my regular disks would benefit from a cache drive.

is that were you set transmissions incomplete download folder? then when they are complete they move to the array?

 

[Stenull]

is that were you set transmissions incomplete download folder? then when they are complete they move to the array?

The idea with cache drive is that files on your main storage being accessed regularly, and if they can't fit in ARC, is copied (by ZFS) to cache and hence the cache drive takes some burden of your main storage pool and your memory.
In my scenario, when seeding some files over and over again I think that my setup would benefit from a cache drive.

 

[handersen]

Am I right in that there still is no GUI option to add a cache disk in 8.0.4-R p1?
I have not physically added the SSD so I might have missed it due to that.

As I understand the feature will be there in 8.2.0, and also that it will be persistent with changes from the CLI.

Is the SSD cache shown in the GUI and kept across reboots etc when added like this?

Sorry for rambling but I can't keep from being a bit hesitant to exporting my pool since it's keeping actual live data which is also why jumping to the beta feels a bit off.. :)

 

[Stenull]

Am I right in that there still is no GUI option to add a cache disk in 8.0.4-R p1?
I have not physically added the SSD so I might have missed it due to that.

As I understand the feature will be there in 8.2.0, and also that it will be persistent with changes from the CLI.

Is the SSD cache shown in the GUI and kept across reboots etc when added like this?

Sorry for rambling but I can't keep from being a bit hesitant to exporting my pool since it's keeping actual live data which is also why jumping to the beta feels a bit off.. :)

Hi, sorry for the delay.
No i don't think there is an GUI option for it in 8.0.4-R p1, but i have not checked it..
Doing it like this will make it persistent and it shows up in GUI as a cache drive. It's now a part of your pool so it will follow you until you detach it again.


I can't guarantee success but it worked for me with out a any problems. Maybe it's safer to wait for 8.2.0.

 

[handersen]

I'd say an answer within 12 hours is no delay.. :)
Big thanks for the feedback!

I'll have to read into export and import a bit more and see if there are any caveats to look out for before I decide, maybe 0.8.2 will be released during.