Confused ZFS SSD cache never seems to read?

[TdC]

Heya chumlars,

I have a question: I have been happily working with a ZFS based raid setup for my storage needs. In recent times I have been keeping an eye on it, and I notice that while I have an SSD as cache, and it IS in use, I never see the system report reads from it -only writes to the device are shown.

cache                                           -      -      -      -      -      -
  scsi-SATA_Samsung_SSD_840S1ANNSAF343281J   118G  1.20G      0     67      0  8.50M

What I do see is that there is an occasional difference between the rotational disks reported read operations, and the ZPool's read operations. If I subtract the former from the latter, would that be the cache reads?

Answers on a postcard please

 

[TdC]

never mind: the very INSTANT I pressed "Create thread" I saw some cache read operations pff :-/

 

[old.user4556]

premature ejaculation tbpfh

 

[caLLous]

I'll have you know that @TdC possesses immense stamin... I'm sorry I couldn't even finish the sentence without giggling like a school girl.

 

[TdC]

you stand in awe of my massive stamen

 

[Deebs]

Google for "arcstat" and download and run a copy specific to your O/S version, that will give you lots of information about your caches, it basically takes the ZFS counters and formats them to a better output.