Writeback cache for linux node

Hi there,

I’m going to put a more RAM soon to my servers, I was thinking to use a few GB of RAM to creade ramdisk as writeback cashe for my SN (8TB snr disc). Yes I do have very reliable backup power supply and RAM memory is ECC.

Does any one of you have any experience with writeback cache as a ramdisk? Any recommendation?

Do you have a panic-proof kernel?

It would be interesting to know if more RAM on a storj node has any effect at all.

If storj uses SYNC for all writes, then more RAM won’t translate to better performance, because there would be no writeback.

No I don’t have :slight_smile:

I’m happy to test it :slight_smile:

But I’m thinking to do a ramdisk in RAM memory and use it as writeback cashe for node disk.

It does not look like the node uses sync for all writes. IIRC the files themselves and some database updates are async. Mounting the filesystem in sync mode produces a lot of i/o.
And yes, that means it is possible for the node to send “ok, I have it” to the client, without having actually stored the data on the drive (yet).

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there is this thing called NVM which people have been using for write cache for the better part of a decade now, maybe you should consider using one of those instead… also then you could do sync writes as well because it’s on disk, ofc that depends on what your cache software will allow you to do…
i’m very happy with my mediocre at best MLC write cache on to which i force both async and sync writes to so that i get more sequential writes onto the HDD, instead of async and sync unloading on their own cycles… thus i basically half my write IO / write time to the HDD / accesses.
this inturn improves my read latency, because the disks can more easily keep up.

if one can say anything is easy about keeping up with the Storagenode IO

ofc this isn’t the perfect solution for everything… but imo it seems to work better than what else i’ve tried.