Re: ZFS melting under postgres...

David Duchscher wrote:
On Dec 14, 2007, at 6:57 AM, Dag-Erling Smørgrav wrote:

David Duchscher <daved@xxxxxxxx> writes:
So does anybody know of a battery backed NVRAM card that can be used
with FreeBSD that the ZIL could be offloaded to?

Any CF card or similar will do. You don't need battery backup for
flash memory.

I did think of that but is a CF card faster than a good SAS or SATA
drive?

Not in transfer rate, but it could help hugely with seek-intensive IO
loads (since seeks are instantaneous on flash or other solid-state
drives). In theory, they could be of immense benefit for databases and
seek-intensive operations on file systems, but the limited bulk transfer
rates and relatively small sizes (for decent money) currently prevent
their wide-spread use.

It would be logical to use a limited size SSD for something like a file
system journal for a large file system, except that these kind of
journals are usually not seek-intensive :)

Fastest ones I found have a top rating of 45MB/s. The one
battery backed NVARM card that showed up in a google search had a peak
rate of 533MB/s. The question seems moot though since FreeBSD doesn't
currently support them.

If a NVRAM or SSD, or other technology presents the drive as a (S)ATA
drive, there's no reason it shouldn't.

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