[sheepdog-users] Object cache (writethru/writeback) on gateway?

icez network icez at icez.net
Thu Jul 5 20:19:20 CEST 2012

I'm using a single instance sheepdog on a RAID10 + Flashcache (
https://github.com/facebook/flashcache/) and is interesting in the object
caching implementation on sheepdog.
So may I ask if thing like this can occurs in sheep

- run each sheep daemon for each disk (4 disks in my setup) on each node
without RAID.
- run gateway and point to SSD mountpoint.
- run QEMU on the same machine (for some node) and connect to gateway.

So the caching will store within gateway path (Am I guessing right?).
I'm thinking that with SSD performance, it should boost I/O performance by
large margin.

As from the above design, may i ask few questions

- Does object caching managed by gateway and store on the SSD?
- The behavior of gateway if cache is filling out all spaces on the SSD.
For example I'm using 120GB SSD which seems enough for general use but
there's some excessive write on the QEMU for backing up their data once a
day which can write a lot of data into it and it may exceed the SSD
capacity. Will it bypass the write to the backend if cache write fail

Best regards,
Khachain Wangthammang

Personal hosting by icez network
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