On Friday 24 June 2011, Benny Lofgren wrote:
> On 2011-06-24 01.39, Matthew Dempsky wrote:
> > What should be done about ccd(4) and raid(4)? They both seem
> > superseded in functionality by softraid(4), which also has much more
> > developer interest and active development.
>
> Never used ccd(4) so can't comment on that, but RAIDframe (raid(4)) has
> a lot of functionality that is not yet implemented in softraid(4).
>
> It has (for good reason given that softraid(4) is in the works) received
> little developer attention and has a few bugs and other shortcomings.
>
> I've tried in the past to address those I've run up against, but I know
> there are probably more problems with it than is worth fixing (in
> particular I've had problems with very large disks and raid sets) so I
> have high hopes for softraid(4) in the future.
>
> > Are there any users still using ccd(4) and/or raid(4) and unable to
> > upgrade to softraid(4)? Will anyone be up a creek if ccd(4)/raid(4)
> > were removed?
>
> I for one will be up the worst of creeks if raid(4) was removed, that
> would force me to stay on 4.9 until softraid(4) have evolved enough
> (which I have no doubt will happen eventually), so please please don't
> remove raid(4) just yet. :-)
>
> My wish list for softraid(4) to enable me to say goodbye to RAIDframe
> is something like this (not exhaustive and in no particular order):
>
> - More complete RAID support overall, including
> - ability to tune stripe sizes
Easily doable - not sure about the benefit since MAXPHYS should be close to
optimal.
> - parity initialization / rebuilding, preferrably with background
> mode
The RAID 4/5/6 disciplines are still lacking this (scrubbing), along with
other things.
> - Hot spare support
We've had that for almost 2 years.
> - Better handling of stripe (disk) failures
Not sure what you're wanting here.
> - Better handling of recovery from failed stripes (ability to hot
> plug a replacement disk and rebuild on the spot for example)
We've had that for almost 2 years as well.
> - Full stripe writes for perfomance
Meaning?
> - Usable status reporting
Are you talking about error messages, or bioctl(8) output?
> - Stripe on stripe (on stripe ...) support to be able to build
> RAID 0+1 and RAID50 sets, as well as crypto on raid (this may
> work now, haven't tried lately)
This works, although is not officially supported at this stage.
> - RAID6 support (way way back in priority though)
>
> - Bootable/rootable raid sets (I know this is close now)
>
> - More consistent sd<n> unit allocation (perhaps this is achievable
> with DUID, I haven't had time to explore that yet)
sd(4) unit allocation will always be inconsistent and unpredicatable - DUIDs
will let you avoid this entirely.
> - Probably other small features as well, that I'll probably think
> of the moment I've sent this mail off...
>
>
> Regards,
> /Benny
--
"Reason is not automatic. Those who deny it cannot be conquered by it.
Do not count on them. Leave them alone." -- Ayn Rand
