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



Andrew Morton wrote:
> 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.

Was this using full-data journaling?
Testing NFS v3 sync clients with large writes?
More importantly, what about post-crash recovery, especially with
NFS?

Just curious.  I could see how this stuff isn't very "cool" for
Samba and typical services, but for NFS v3 servers using sync
writes, I would be shocked if it didn't help at all.

Thanx for the info.  Any URLs to the archives would be greatly
appreciated.

-- Bryan

-- 
Bryan J. Smith, Engineer        mailto:b j smith ieee org   
AbsoluteValue Systems, Inc.     http://www.linux-wlan.org
SmithConcepts, Inc.          http://www.SmithConcepts.com
---------------------------------------------------------
1999 IRS Data:  The richer half of all US income
                earners pay 99% of all US taxes





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