large l2, low physical mem overhead cache possible?

[joliet]

Not sure if this is more properly a suggestion or just me being dumb about how this can ever actually work, but,

Let's say you have what I have -

4gb of memory
250gb primary SSD
120gb secondary SSD
1x 3tb hd
2x 1tb hd

What I figured I could use Primocache for is to turn the 120gb SSD drive into a dedicated cache drive, like the integrated intel/pcie card SSD's. But if I even try and set that up to cache that many HDD volumes (5tb over 3 HDDs) I don't have anywhere near the physical memory overhead to do it (4.69gb just in overhead for the cache).

Is this just too dumb to work? Can primocache work like this? Does any software do this? I've googled around and apparently pretty much everything that vaguely does the thing I want is some oem-only or other proprietary software?

[Support]

You can setup a low L1 cache such as 128MB. And set up a bigger block size which will reduce the overhead a lot.

[InquiringMind]

You may also want to consider combining some of the hard drives (e.g. the 3 x 1TB ones) into a single RAID volume so they can use the same cache (RAID-0 should give a performance boost, but make sure you backup regularly!).

Also if the drives are used to hold rarely accessed data (videos watched infrequently, document backups, software downloads) then there isn't any point in caching them - caching only provides benefits with data accessed repeatedly.

[joliet]

Ah, haha, ok. My bad - I had no idea increasing the block size would decrease overhead! I thought bigger blocks = bigger overhead, not smaller

I'm using them primarily to edit videos (2 10k, 1 7200rpm). I have the 250gb ssd with a small l1 cache of it's own, and the smallest l1 and the entire 120 SSD set up as cache for the hds now and there seems to be a good performance improvement - even just for small things like refreshing folder contents and drilling down subdirs seems snappier, just all those little filesystem delays seem to be improved. Definite quality of life improvement anyhow.

Thanks for the help guys.