Jeremy Teo wrote On 01/11/07 01:38,:
On 1/11/07, Erik Trimble <[EMAIL PROTECTED]> wrote:
Just a thought: would it be theoretically possible to designate some
device as a system-wide write cache for all FS writes? Not just ZFS,
but for everything... In a manner similar to which we currently use
extra RAM as a cache for FS read (and write, to a certain extent), it
would be really nice to be able to say that a NVRAM/Flash/etc. device
is the system-wide write cache, so that calls to fsync() and the like -
which currently force a flush of the RAM-resident buffers to disk -
would return as complete after the data was written to such a SSD (even
though it might not all be written to a HD yet).
As a first step, we could just mark the physical vdev(s) corresponding
to such device(s), and use that as the sole backing store for the ZIL.
That would give us a quick win for the NFS/ZFS model.
We are currently working on separate log devices such as disk and nvram.
This should help with both NFS and DB performance.
Neil.
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