Is it redundant to allocate L2 cache for an SSD drive

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LawrenceLee
Posts: 13
Joined: Sat Nov 02, 2019 1:50 am

Is it redundant to allocate L2 cache for an SSD drive

Post by LawrenceLee »

Support,

I am using Primo cache with a combination of SSD storage drives and a large 4 TB mirror raid drives. I'm noticing when they share tasks with L1 and L2 cache, that the cache apparently is active when I request data from another SSD drive. So it appears that PrimoCache is using SSD space in the L2 cache to cache SSD data. Is this really happening? It seems redundant.

If this is true then it seems that I should the only allocate L1 memory for my SSDs. Should I allocate L1 and L2 cache space for a 4TB spinning hard drive. Or should I rather just use L2 [SSD] cash for my physical hard drive?

cichy45
Posts: 35
Joined: Sun Oct 14, 2018 3:34 pm

Re: Is it redundant to allocate L2 cache for an SSD drive

Post by cichy45 »

Yes, Primocache will use L2 SSD cache to cache another SSD if you set your options to do so. Someone might want to cache large 4TB SATA SSD with fast 256GB M.2 NVME for example.


As for your second question - it depends, as always. If you need hundreds of thousands IOPS then you should use L1 RAM cache for your 4TB HDD. If you mainly need sequential performance and lower IOPS (like few thousands per second) then only L2 SSD cache will be enough.
However, if you do not have any heavy load on your disk I would not set cache for SSD at all, only for HDD.

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support
Posts: 2712
Joined: Sun Dec 21, 2008 2:42 am

Re: Is it redundant to allocate L2 cache for an SSD drive

Post by support »

You may disable L2 cache for that SSD volume in the "Volume Specifications" in the configuration dialog, if you use a share cache task.
Primo Ramdisk | PrimoCache
Romex Software Support

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