Am 28.05.2012 07:37, schrieb Alexandre DERUMIER:
I think filestore journal parallel works only with btrfs.
Other filesystem are writeahead.
... you might be right but i can't change ceph's implementation.
if you write at 120MB/S, so your journal of 1GB is at 50% in 4sec.
So you got around 480MB each 4sec, does your disks can flush sequentially these 480MB in less than 4sec ?
(do a small benchmark of your disk in local filesystem, without ceph)
If not, you can have spikes in your write stats if the journal.
simple schema if disks are not fast enough:
I totally aggree with you but this is just a test setup AND if you have
a big log file to copy let's say 100GB your journal will never be big
enough and the speed should never drop to 0MB/s. Also i see the correct
behaviour with 3.0.X where the speed is maxed to the underlying device.
So i still see no reason that with 3.4 the speed drops to 0MB/s and is
mostly 10-20MB/s instead of 130MB/s.
How many disks (7,2K) do you have by osd ?
One intel 520 SSD per OSD.
Stefan
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