Sorry if this question seems a bit silly, but when messing around with established pools, Id rather be safe then sorry. My arc hit ratio averages around 80%, So i have a 250Gb SSD i want to add as a L2ARC cache, just becasue i have it laying around and not using it. I want to add this SSD to see how it performs with it vs without. Im not entirely confident on how to add this as a cache device. Id rather not nuke my pool by accident by adding it the wrong way. Can someone clarify the correct steps to add this? The guide says to "extend" the pool to add a cache device, but I can also add it as a new pool. I want to be able to remove it if it hurts performance, and not accidentally add it to a pool that would have to be rebuilt to correct. Im pretty sure that "extend" pool / ADD CACHE / ->Cache VDEV / EXTEND is the correct way to add this, but i want to make sure. Can someone clarify this for me please?
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Adding L2ARC Cache
- Thread starter G8One2
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You should remove the empty data vdev if you can, but that's the right path to it.
As a general rule, L2ARC isn't helpful unless you're getting a lot of ARC misses... have you checked? With that much RAM, I'd be surprised.
As a general rule, L2ARC isn't helpful unless you're getting a lot of ARC misses... have you checked? With that much RAM, I'd be surprised.
That empty vdev is what shows up when I select "extend" pool. I only have 1 pool so Im not sure why that shows as empty. I suspect its because i thinks Im adding vdevs to an existing pool. The cache vdev pops up when i select add cache. Not sure about arc misses, below is what my system is reporting. I do not have any performace issues with my system, lets just clarify that. Im always looking to make things better though. It seems the more my data pools grow, the smaller my hit ratio gets. Which is why Im looking to add the L2ARC. But, this is just for comparisons sake.
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Depends what you're expecting to improve by doing that... are you doing a lot of synchronous writing (usually iSCSI or VM block storage)?
