write-intent bitmaps

[Russell Coker]

On Sunday 27 January 2008 22:21, Neil Brown <neilb at suse.de> wrote:
> On Sunday January 27, russell at coker.com.au wrote:
> > http://lists.debian.org/debian-devel/2008/01/msg00921.html
> >
> > Are they regarded as a stable feature?  If so I'd like to see
> > distributions supporting them by default.  I've started a discussion in
> > Debian on this topic, see the above URL for details.
>
> Yes, it is regarded as stable.

Thanks for that information.

> However it can be expected to reduce write throughput.  A reduction of
> several percent would not be surprising, and depending in workload it
> could probably be much higher.

It seems to me that losing a few percent of performance all the time is better 
than a dramatic performance loss for an hour or two when things go wrong.

> It is quite easy to add or remove a bitmap on an active array, so
> making it a default would probably be fine providing it was easy for
> an admin to find out about it and remove the bitmap is they wanted the
> extra performance.

I hadn't realised that.  So having this in the installer is not as important 
as I previously thought.

-- 
russell at coker.com.au
http://etbe.coker.com.au/          My Blog

http://www.coker.com.au/sponsorship.html Sponsoring Free Software development