Possible to disable L2ARC for a volume?

[geekmaster64]

Hey there,

Is it possible to disable the L2ARC or ARC for a specific volume? For example, I have a volume that is strictly media, whereas other volumes are VM's or other's that would benefit from the L2ARC. I did several searches on the forums and wasn't able to find anything.

Thanks!

 

[Chris Moore]

Hey there,

Is it possible to disable the L2ARC or ARC for a specific volume? For example, I have a volume that is strictly media, whereas other volumes are VM's or other's that would benefit from the L2ARC. I did several searches on the forums and wasn't able to find anything.

Thanks!

It is my understanding that a L2ARC is applied to the entire pool. If you want a portion of the storage to have one performance characteristic and another portion of the storage to have a different characteristic, they need to be separate pools. For exapmple, in my primary storage server, I have one pool that is made of 2 RAIDz2 vdevs (12 drives total) and I use that for mass storage of regular files and media such as movies. I have another pool that is made of 8 mirror vdevs (16 drives) and I use that for my iSCSI storage for fast access, near line speed on 10Gb networking. One pool is for slow storage and the other is for fast storage and they are configured totally different because the performance is dictated by the hardware. Still, adding a SLOG or L2ARC device to a pool is a pool wide setting, not done per dataset.

 

[geekmaster64]

It is my understanding that a L2ARC is applied to the entire pool. If you want a portion of the storage to have one performance characteristic and another portion of the storage to have a different characteristic, they need to be separate pools. For exapmple, in my primary storage server, I have one pool that is made of 2 RAIDz2 vdevs (12 drives total) and I use that for mass storage of regular files and media such as movies. I have another pool that is made of 8 mirror vdevs (16 drives) and I use that for my iSCSI storage for fast access, near line speed on 10Gb networking. One pool is for slow storage and the other is for fast storage and they are configured totally different because the performance is dictated by the hardware. Still, adding a SLOG or L2ARC device to a pool is a pool wide setting, not done per dataset.

Thank you! I was hoping I wouldn't have to do that as I have a limited number of drives. I appreciate your quick and accurate response Chris :)

 

[Paul van der Zwan]

Hey there,

Is it possible to disable the L2ARC or ARC for a specific volume? For example, I have a volume that is strictly media, whereas other volumes are VM's or other's that would benefit from the L2ARC. I did several searches on the forums and wasn't able to find anything.

Thanks!

It should be possible to keep some datasets or zvols from using the L2ARC by setting their secondarycache property to ‘none’.
Or setting it to ‘metadata’ to keep file data from the cache but have metadata cached.
The primarycache property controls the ARC.

Paul

 

[geekmaster64]

It should be possible to keep some datasets or zvols from using the L2ARC by setting their secondarycache property to ‘none’.
Or setting it to ‘metadata’ to keep file data from the cache but have metadata cached.
The primarycache property controls the ARC.

Paul

Really? That would be extremely useful. In other storage systems like Nimble, it's controlled by a per volume basis which made it really handy. I'll have to do some more reading around those controls.