ANNOUNCE: mdadm 3.1.2 - A tool for managing Soft RAID under Linux

ANNOUNCE: mdadm 3.1.2 - A tool for managing Soft RAID under Linux

[Neil Brown]

I am pleased to announce the availability of
   mdadm version 3.1.2

It is available at the usual places:
   countrycode=xx.
   http://www.${countrycode}kernel.org/pub/linux/utils/raid/mdadm/
and via git at
   git://neil.brown.name/mdadm
   http://neil.brown.name/git?p=mdadm

This is a bugfix/stability release over 3.1.1.

Significant changes are:
  - The default metadata has change again (sorry about that).
    It is now v1.2 and will hopefully stay that way.  It turned
    out there with boot-block issues with v1.1 which make it 
    unsuitable for a default, though in many cases it is still
    suitable to use.
  - Stopping a container is not permitted when members are still
    active
  - Add 'homehost' to the valid words for the "AUTO" config file
    line.  When followed by "-all", this causes mdadm to
    auto-assemble any array belonging to this host, but not
    auto-assemble anything else.
  - Fix some bugs with "--grow --chunksize=" for changing chunksize.
  - VAR_RUN can be easily changed at compile time just like ALT_RUN.
    This gives distros more flexability in how to manage the
    pid and sock files that mdmon needs.
  - Various mdmon fixes
  - Alway make bitmap 4K-aligned if at all possible.
  - If mdadm.conf lists arrays which have inter-dependencies,
    the previously had to be listed in the "right" order.  Now
    any order should work.
  - Fix --force assembly of v1.x arrays which are in the process
    of recovering.
  - Add section on 'scrubbing' to 'md' man page.
  - Various command-line-option parsing improvements.
  - ... and lots of other bug fixes.


This release is believed to be stable and you should feel free to
upgrade to 3.1.2

NeilBrown 10th March 2010

Re: ANNOUNCE: mdadm 3.1.2 - A tool for managing Soft RAID under Linux

[Asdo]

Neil Brown wrote:
> I am pleased to announce the availability of
>    mdadm version 3.1.2
>
> [CUT]
>
> Significant changes are:
>   - The default metadata has change again (sorry about that).
>     It is now v1.2 and will hopefully stay that way. 
> [CUT]
>   
I remember some discussion about alignment for 1.1 and 1.2: is it 
possible on 1.2 to guarantee alignment of RAID device on the physical 
devices?
4K alignment would be needed on SSDs and 2TB disks w/ 4k physical 512b 
logical emulation. Actually on SSDs the alignment could be even more 
than 4k, I am not sure.
Should we bypass the defaults and put 1.0 metadata on those?
What was the downside of 1.0 so that it was not made default?

Thanks for your great job

Re: ANNOUNCE: mdadm 3.1.2 - A tool for managing Soft RAID under Linux

[Michael Evans]

On Thu, Mar 11, 2010 at 3:25 AM, Asdo <asdo@shiftmail.org> wrote:
> Neil Brown wrote:
>>
>> I am pleased to announce the availability of
>>   mdadm version 3.1.2
>>
>> [CUT]
>>
>> Significant changes are:
>>  - The default metadata has change again (sorry about that).
>>    It is now v1.2 and will hopefully stay that way. [CUT]
>>
>
> I remember some discussion about alignment for 1.1 and 1.2: is it possible
> on 1.2 to guarantee alignment of RAID device on the physical devices?
> 4K alignment would be needed on SSDs and 2TB disks w/ 4k physical 512b
> logical emulation. Actually on SSDs the alignment could be even more than
> 4k, I am not sure.
> Should we bypass the defaults and put 1.0 metadata on those?
> What was the downside of 1.0 so that it was not made default?
>
> Thanks for your great job
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

1.0 puts the metadata at the end.  You run in to situations where
various tools that detect what's inside of a block device get confused
about if it's an md member, or whatever's been stuffed inside of md
(and is thus stored at the front) instead.

What would be nice would be the ability to specify a non-default
alignment unit and a reference sector in the backing device to use for
the start of alignment.  However I don't think anyone who's really
needed it has yet seen fit to provide a patch.

Presuming someone did want to write a patch, is the above outlined
pair of options desirable as the solution, and what sort of long/short
names might be used?
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: ANNOUNCE: mdadm 3.1.2 - A tool for managing Soft RAID under Linux

[Luca Berra]

On Thu, Mar 11, 2010 at 12:25:22PM +0100, Asdo wrote:
> Neil Brown wrote:
>> I am pleased to announce the availability of
>>    mdadm version 3.1.2
>>
>> [CUT]
>>
>> Significant changes are:
>>   - The default metadata has change again (sorry about that).
>>     It is now v1.2 and will hopefully stay that way. [CUT]
>>   
> I remember some discussion about alignment for 1.1 and 1.2: is it possible 
> on 1.2 to guarantee alignment of RAID device on the physical devices?
> 4K alignment would be needed on SSDs and 2TB disks w/ 4k physical 512b 
> logical emulation. Actually on SSDs the alignment could be even more than 
> 4k, I am not sure.
is there any problems with this commit?
http://neil.brown.name/git?p=mdadm;a=commit;h=a380e2751efea7dfe8acf0b95419c65ccacfa7cf

> Should we bypass the defaults and put 1.0 metadata on those?
> What was the downside of 1.0 so that it was not made default?
this has been discussed to boredom

L.

-- 
Luca Berra -- bluca@comedia.it
         Communication Media & Services S.r.l.
  /"\
  \ /     ASCII RIBBON CAMPAIGN
   X        AGAINST HTML MAIL
  / \

Re: ANNOUNCE: mdadm 3.1.2 - A tool for managing Soft RAID under Linux

[Asdo]

Luca Berra wrote:
> On Thu, Mar 11, 2010 at 12:25:22PM +0100, Asdo wrote:
>> I remember some discussion about alignment for 1.1 and 1.2: is it 
>> possible on 1.2 to guarantee alignment of RAID device on the physical 
>> devices?
>> 4K alignment would be needed on SSDs and 2TB disks w/ 4k physical 
>> 512b logical emulation. Actually on SSDs the alignment could be even 
>> more than 4k, I am not sure.
> is there any problems with this commit?
> http://neil.brown.name/git?p=mdadm;a=commit;h=a380e2751efea7dfe8acf0b95419c65ccacfa7cf 
>
>
Oh it IS aligned then

>> Should we bypass the defaults and put 1.0 metadata on those?
>> What was the downside of 1.0 so that it was not made default?
> this has been discussed to boredom
I'm sorry