What is the status of the raid5 online resize patch ?

What is the status of the raid5 online resize patch ?

[Francois Barre]

Hello all,

Surfing on the web I found a patch from Steinar H. Gunderson which
implements raid5 resize stuff.
(http://marc.theaimsgroup.com/?l=linux-raid&m=112998877619952&w=2).
It seems like it has been included in the 2.6.14 kernel
(http://www.linuxhq.com/kernel/v2.6/14/drivers/md/raid5.c), but I
would be sure :
- Is it really reliable ? Did you test it strongly enough to put the
'I trust it' label on it ?
- Does it implement crash recovery now ?
- Did anyone test a multiple growth (add 1 disk, then another, then...).

That could be really interresting to know.

Thanks for advance,

F.-E. Barre.

Re: What is the status of the raid5 online resize patch ?

[Neil Brown]

On Thursday December 1, francois.barre@gmail.com wrote:
> Hello all,
> 
> Surfing on the web I found a patch from Steinar H. Gunderson which
> implements raid5 resize stuff.
> (http://marc.theaimsgroup.com/?l=linux-raid&m=112998877619952&w=2).
> It seems like it has been included in the 2.6.14 kernel
> (http://www.linuxhq.com/kernel/v2.6/14/drivers/md/raid5.c), but I

No, it hasn't been included.  The raid5 changes reflected at that url
are mostly 'bitmap write-intent log' which optionally accelerates
resync speed at a small cost of write speed.

> would be sure :
> - Is it really reliable ? Did you test it strongly enough to put the
> 'I trust it' label on it ?
> - Does it implement crash recovery now ?
> - Did anyone test a multiple growth (add 1 disk, then another, then...).
> 

However, I expect to have time to complete the very good work that
Steinar started early in the new year.  It will not be submitted to
-mm until it implements crash recovery and has been tested for
multiple growth and other scenarios. 
It will not go to -linus until it has been tested quite thoroughly
(preferably by more than just me) and I would feel comfortable using
it on my data.

I look forward you getting your test results after it is in -mm :-)

NeilBrown

Re: What is the status of the raid5 online resize patch ?

[Francois Barre]

Ok, thanks for your answer.

Then I suppose I will have to wait a bit.
If I can be of any help for testing and hacking purpose, please let me know.
I think I will really *need* this feature by the end of february,
2006. Do you think I have any chance to use it safely by that time ?

Best regards,

F.-E. Barre.

2005/12/1, Neil Brown <neilb@suse.de>:
> On Thursday December 1, francois.barre@gmail.com wrote:
> > Hello all,
> >
> > Surfing on the web I found a patch from Steinar H. Gunderson which
> > implements raid5 resize stuff.
> > (http://marc.theaimsgroup.com/?l=linux-raid&m=112998877619952&w=2).
> > It seems like it has been included in the 2.6.14 kernel
> > (http://www.linuxhq.com/kernel/v2.6/14/drivers/md/raid5.c), but I
>
> No, it hasn't been included.  The raid5 changes reflected at that url
> are mostly 'bitmap write-intent log' which optionally accelerates
> resync speed at a small cost of write speed.
>
> > would be sure :
> > - Is it really reliable ? Did you test it strongly enough to put the
> > 'I trust it' label on it ?
> > - Does it implement crash recovery now ?
> > - Did anyone test a multiple growth (add 1 disk, then another, then...).
> >
>
> However, I expect to have time to complete the very good work that
> Steinar started early in the new year.  It will not be submitted to
> -mm until it implements crash recovery and has been tested for
> multiple growth and other scenarios.
> It will not go to -linus until it has been tested quite thoroughly
> (preferably by more than just me) and I would feel comfortable using
> it on my data.
>
> I look forward you getting your test results after it is in -mm :-)
>
> NeilBrown
>

Re: What is the status of the raid5 online resize patch ?

[Neil Brown]

On Thursday December 1, francois.barre@gmail.com wrote:
> Ok, thanks for your answer.
> 
> Then I suppose I will have to wait a bit.
> If I can be of any help for testing and hacking purpose, please let me know.
> I think I will really *need* this feature by the end of february,
> 2006. Do you think I have any chance to use it safely by that time ?

There is a chance, but not a promise.

NeilBrown