Adding Cache?

[ozlefty]

Hello!

First Post here and new to Truenas.

I would like to add a cache (which is a virtual disk from vmware) to my pool.

I have created it and truenas can see it, I just cant work out how to add to the pool as a cache?

I have tried and cant seem to work it out.. can somebody tell me if its possible?

Any help appreciated :)

 

[jgreco]

Welcome to the forums.

Sorry to hear you're having trouble. Please consider following the Forum Rules, conveniently linked at the top of every page in red, which ask that you post a detailed hardware manifest of your system. This will help provide some context for community members to comment on your system.

Adding L2ARC to your system is an easy way to improve some aspects of read performance, but it is important to remember that you really need to have maxxed out regular ARC first. Typically an L2ARC device isn't that useful until after you've already gotten to 64GB of RAM, though it is possible for it to have positive impacts with 32GB or even 24GB if you're using it exclusively for metadata. This is because ZFS needs to be able to identify useful content through the ARC's MRU/MFU mechanisms that qualify for eviction to the L2ARC.

Please take a little time to provide additional details about your system and we can provide some guidance here.

 

[NugentS]

to add to what @jgreco says. A cache in ZFS doesn't exist inthe same way that a cache in UNRAID exists. So when someone comes on this forum saying they want to add a cache - its usually (but not always) the case that they don't understand what they are asking for.

A Cache (L2ARC is probably the closest match) will not help writes at all and MIGHT help speeds depending on your existing ARC (Memory) and your use case.

To help we need, not just your hardware spec, but also your use case.

 

[ozlefty]

Hi Thanks for the reply and ssorry for the delay

Motherboard is a HP microserver N54L
CPU is 2 core AMD turion
12 Gigs of Ram
Hard disks: 1 x 8tb Seagate, 1 x 6tb Seagate, Boot drive 128gig kingston SSD
Raid configuration is Raid0
Network card is Gigabit onboard

I would like to add some of the SSD to make a cache drive.

Is this possible and worth while?

 

[NugentS]

No its not worthwhile.
Adding L2ARC will use up some of your ARC, and you don't exactly have a lot of that in the first place.

Leave well alone

 

[LarsR]

https://www.youtube.com/watch?v=M4DLChRXJog explains everything you need to know about zfs log & l2arc

 

[jgreco]

https://www.youtube.com/watch?v=M4DLChRXJog explains everything you need to know about zfs log & l2arc

Please note that we have plenty of resources on these forums explaining this, and do not wish to drive people over to the monetization engine at Google.

 

[ozlefty]

thank you for the information!

Leaving well alone :)