L1 cache with drives from L2 cache + another Topic is solved

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MikeC
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L1 cache with drives from L2 cache + another

Post by MikeC »

My system has an M.2 SSD for its C drive and 2 mechanical drives for E and F. I've setup E and F to cache to an L2 cache on a spare SATA SSD.

I would like to, if possible, setup an L1 cache that would contain C, E, and F. Is this possible and our prudent? My thought is that the resulting L1 would handle the really-frequently accessed files and the L2 would then speed up files that are coming from the magnetic drives. In this scenario, again if it is possible, would some files get double cached?

Mike
Kalex
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Re: L1 cache with drives from L2 cache + another

Post by Kalex »

This is possible and, I think, the most commonly used configuration.

I, for example, have 2 NVMe-Drives and 4 HDDs.
I use a RAID0 of 3 SATA SSDs as a L2-Cache in addition to L1-Cache.
Via the volume specifcations dialog I set up that all NVMe-Drives are allowed to use the L1-Cache while all HDDs are allowed to use the L1- and the L2-Cache.
This works very well for me.

In Addition you can also set "Flush L1 Cache to L2 Cache" in the defer-write options, so once your L1-Cache gets full, it'll first move the data to the L2 instead of flushing it to the HDDs.
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Re: L1 cache with drives from L2 cache + another

Post by Support »

As Kalex said, L1 + L2 is the most commonly used configuration.
Kalex wrote: Fri Oct 07, 2022 2:27 pm In Addition you can also set "Flush L1 Cache to L2 Cache" in the defer-write options, so once your L1-Cache gets full, it'll first move the data to the L2 instead of flushing it to the HDDs.
I would add that this option
I would add that this option applies to the configuration in which both L1 and L2 is used for Defer-Write. By default, L2 is for read cache only. For more information about Defer-Write, please see https://www.romexsoftware.com/en-us/pri ... write.html
MikeC
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Re: L1 cache with drives from L2 cache + another

Post by MikeC »

So, when making an L1 with drives that are already in an L2, does PrimoCache automatically handle knowing to cache to the L1 first and then to the L2 when the L1 gets full? Or, do I need to do something in the setup process to accommodate that situation?
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Re: L1 cache with drives from L2 cache + another

Post by Support »

L2 cache is slightly different from L1 cache because L2 cache is persistent. It is possible that data are cached both in L1 and L2. L2 tries to cache all data which has read in order to still can provide cache even after reboot. For more details about L2 cache, please see
https://www.romexsoftware.com/en-us/pri ... cache.html
TomB
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Re: L1 cache with drives from L2 cache + another

Post by TomB »

I don't see how to do this.

If my first task caches ssd and hdd to L1, then my second task which would cache hdd to l2 also, cannot add hdd to task because drive is already cached in first task.

What am I missing?

Thanks in advance ...

Tom
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Re: L1 cache with drives from L2 cache + another

Post by Support »

A drive can be cached by one cache task only. You can set up L1 and L2 in one cache task.

If this task caches both HDDs and SSDs, you can disable L2 for SSDs in the "Volume Specification" (in the cache configuration dialog).
TomB
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Re: L1 cache with drives from L2 cache + another

Post by TomB »

Ah-ha, now I see! I will try this!

Thank you very much!!

:)

Tom
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