Share L1-cache between drives?

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Incriminated
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Share L1-cache between drives?

Post by Incriminated »

Hello,

i actually have a 4GiB r/w-L1-cache for my SSD and another 1GiB r/w-L1-cache for my HDD.

So when i transfer a file from my HDD to my SSD it reads the file into the HDD-L1-cache, then passes it on to the SDD-L1-cache waiting there for a flush to disk.

I think it would be quite better to have one single L1-cache and have that beeing shared to be accessed by all drives.

That way the file would be read-in and can be directly flushed to the target disk, so does not need to be copied to another region on the ram first.

Additionally this save huge amout or Cache depending on how much disks you have. I for example have 4 HDDs and 1 SDD, so from my point of view 4x1GiB + 1x4Gib is very less effective. Let's say you would have a single 8 GiB r/w-L1-Ram-Cache for all drives at the same time.

I see that might run into problems with different block size for different drives, so im not sure if that is dooble anyhow.

WIll that kind of feature be available in future version?
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Nina
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Re: Share L1-cache between drives?

Post by Nina »

Datacore's Uptempo uses this technique. it was the best, years ago before they discontinued their awesome product. Hope to see this feature in FC.
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Support
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Re: Share L1-cache between drives?

Post by Support »

In the next version, we can use one single cache for multiple volumes. However we cannot share cache content between volumes. For a block-level caching program, it is difficult to know what files are used across volumes.
Incriminated
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Re: Share L1-cache between drives?

Post by Incriminated »

Sounds good at first instance.

The shared read-cache is one instance, im not afraid about that.

What bugs me is the write-cache, when you simply transfer a file from one disk to another.
A 1-GiB data-transfer from one drive to another with one single cache file (without beeing able to share it to the another volume) would cause 2GiB needed to be used.

In case i only setup 2GiB at all for r/wa-cache and do a 1GiB transfer from one drive to another: all my stored read-cache would be gone. :(

When i transfer 2GiB between 2 drives using a shared single cache with 2GiB.... i don't know how that may screw ... but i like testing O.o
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