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Re: [Off-topic] Battery Backed NVRAM for journals ...

"Bryan J. Smith" wrote:
> I've seen this come up on occassion, but every NAS OEM that uses
> NVRAM I've ever talked to over the last 18 months won't tell me
> anything about their equipment nor their suppliers.

A fair bunch of people did a fair bunch of testing of this last year.
Bottom line: RAM-based journals don't speed ext3 up.

The testing was performed with a ramdisk-based journal,
`trd' which is buried in the ext3 CVS server somewhere.  I'd
suggest that you have a good play with that before shelling
out, or getting your hopes up.

Please bear in mind that the external journal support is
completely experimental, may change any time, may rot your
socks, etc.

The disappointing performance changes are not really surprising.
A journal write is a single seek.  And with most any workload,
there's a complete storm of seeking going on, so the cost of
the journal seek is very low.


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