add second cache drive?

[adoucette]

How do I add a second cache drive? I have an SSD set as the cache, has been working well, and I have recently added a second. I don't see how to add this second SSD to the cache through the web GUI.

I'm running unRAID 6.0.1

Thank you,

Ari

[adoucette]

Nevermind -- looks like I need to decrease the number of slots on the array in the GUI so I can add a slot to the parity.

[bigsing]

Nevermind -- looks like I need to decrease the number of slots on the array in the GUI so I can add a slot to the parity.

 

Yep i ran into the same issue earlier today.  Don't forget to click on the initial cache drive entry and run the balance command.

[adoucette]

I have added the second cache drive, rebooted machine, gone to the first cache device's page and run the 'balance' and the 'scrub' commands. Still, only the first device looks like it's being used in the cache pool (at least what the GUI seems to me to indicate). Is there something I'm doing wrong here? Please see attached screen captures.

 

 

 

 

 

 

Ari

[adoucette]

Again, I'm not sure the second cache drive has been added properly to unRAID. Please see the images above from the web UI, but here's the command line output:

root@Server:~# df -aTh
Filesystem     Type       Size  Used Avail Use% Mounted on
tmpfs          tmpfs      128M  3.2M  125M   3% /var/log
proc           proc          0     0     0    - /proc
sysfs          sysfs         0     0     0    - /sys
/dev/sda1      vfat        15G  146M   15G   1% /boot
/dev/md1       xfs        3.7T  2.9T  813G  79% /mnt/disk1
/dev/md2       xfs        1.9T   17G  1.9T   1% /mnt/disk2
/dev/md3       xfs        1.9T   33M  1.9T   1% /mnt/disk3
/dev/sde1      btrfs      112G   11G  101G  10% /mnt/cache
shfs           fuse.shfs  7.3T  2.9T  4.5T  40% /mnt/user0
shfs           fuse.shfs  7.4T  2.9T  4.6T  39% /mnt/user
/dev/loop0     btrfs       10G  1.3G  7.0G  16% /var/lib/docker

 

I only see the one cache mounted.

Am I missing something here, or is only one cache drive being used? How do I fix this?

Thank you for any help,

Ari

[RobJ]

I have no experience myself here, so hopefully someone else will correct me, but I think what you are showing above looks right.  You have set up a Cache Pool, not a Cache drive, so you would have 120GB total in a RAID1 setup.  I believe for the pool, it reports all Cache usage and numbers on the first line only, because they aren't separate logical drives here any more, they are a single pool.  The numbers all look right.

[adoucette]

Thanks Rob. If that's the case, how do I apply fstrim to both cache drives?

/sbin/fstrim -v /mnt/cache | logger

works just fine, and I get this in the log:

Server logger: /mnt/cache: 10687275008 bytes were trimmed

But when I try the same for cache2, I get nothing but errors. I've tried

/sbin/fstrim -v /mnt/cache2 | logger

/sbin/fstrim -v /mnt/sde | logger

and

/sbin/fstrim -a | logger

But no joy...

[RobJ]

No idea, and I couldn't find anyone else who's tried it, somewhat surprising!  So if you figure it out, tell the rest of us.  The main thread about trimming is here, perhaps a good place for additional questions or reports.

[adoucette]

I had already added the trim cron job using the code from that forum post.

In case anyone else finds it helpful, here's what I did:

Telnet into the unRAID server using PuTTY on Windows port 23

Log in, then enter the following at the command line:

cat > /boot/custom/DailyCacheTrim
#
# Trim the SSD cache drive.
#
/sbin/fstrim -v /mnt/cache | logger

and

echo "#" >> /boot/config/go
echo "# Set up daily SSD cache trim for unRaid cron." >> /boot/config/go
echo "#" >> /boot/config/go
echo "fromdos < /boot/custom/DailyCacheTrim > /etc/cron.daily/DailyCacheTrim" >> /boot/config/go

echo "chmod +x /etc/cron.daily/DailyCacheTrim" >> /boot/config/go

 

I do see the result in the system log at 0440 every day, but I still don't know if it is trimming both cache drives or just one cache drive...