Very small bug on assemble --force

Very small bug on assemble --force

[Ethan Wilson]

Very small bug report:
mdadm assemble --force fails to assemble at the very last step after 
having adjusted the event count:


root@storage1:/root# mdadm --assemble /dev/md106 --config 
/etc/mdadm/mdadm.secondary.conf --force
mdadm: forcing event count in 
/dev/mapper/mpathid-350014ee0ac5a112e-part1(3) from 1058 upto 1061
mdadm: forcing event count in 
/dev/mapper/mpathid-350014ee056feaaf4-part1(4) from 1058 upto 1061
mdadm: forcing event count in 
/dev/mapper/mpathid-350014ee001a93ede-part1(6) from 1058 upto 1061
mdadm: clearing FAULTY flag for device 1 in /dev/md106 for 
/dev/mapper/mpathid-350014ee0ac5a112e-part1
mdadm: clearing FAULTY flag for device 5 in /dev/md106 for 
/dev/mapper/mpathid-350014ee056feaaf4-part1
mdadm: clearing FAULTY flag for device 8 in /dev/md106 for 
/dev/mapper/mpathid-350014ee001a93ede-part1
mdadm: Marking array /dev/md106 as 'clean'
mdadm: /dev/md106 assembled from 8 drives - not enough to start the array.

mdadm is wrong here: 8 devices is indeed the total number of devices for 
this array.
the last command started it inactive like this:

md106 : inactive dm-101[0](S) dm-24[9](S) dm-107[6](S) dm-103[5](S) 
dm-123[4](S) dm-95[3](S) dm-105[2](S) dm-106[1](S)
       4193255424 blocks super 1.2
(maybe the blocks count is also wrong? Not adjusted for parity maybe? 
4193255424  / 8.0 * 6.0 == 3144941568.0 almost correct)

it can be fixed simply by doing:

root@storage1:/root# mdadm --stop /dev/md106
mdadm: stopped /dev/md106

root@storage1:/root# mdadm --assemble /dev/md106 --config 
/etc/mdadm/secondary.conf --no-degraded
mdadm: /dev/md106 has been started with 8 drives.

now it works:

md106 : active raid6 dm-101[0] dm-24[9] dm-107[6] dm-103[5] dm-123[4] 
dm-95[3] dm-105[2] dm-106[1]
       3144938496 blocks super 1.2 level 6, 512k chunk, algorithm 2 
[8/8] [UUUUUUUU]
       bitmap: 0/1 pages [0KB], 1048576KB chunk

Regards
EW

Re: Very small bug on assemble --force

[NeilBrown]

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On Tue, 28 Oct 2014 15:27:02 +0100 Ethan Wilson <ethan.wilson@shiftmail.org>
wrote:

> Very small bug report:

Thanks for the bug report.
However, please always quote version of mdadm and version of Linux.

I think this might have been fixed already, in mdadm 3.3.1.

NeilBrown


> mdadm assemble --force fails to assemble at the very last step after 
> having adjusted the event count:
> 
> 
> root@storage1:/root# mdadm --assemble /dev/md106 --config 
> /etc/mdadm/mdadm.secondary.conf --force
> mdadm: forcing event count in 
> /dev/mapper/mpathid-350014ee0ac5a112e-part1(3) from 1058 upto 1061
> mdadm: forcing event count in 
> /dev/mapper/mpathid-350014ee056feaaf4-part1(4) from 1058 upto 1061
> mdadm: forcing event count in 
> /dev/mapper/mpathid-350014ee001a93ede-part1(6) from 1058 upto 1061
> mdadm: clearing FAULTY flag for device 1 in /dev/md106 for 
> /dev/mapper/mpathid-350014ee0ac5a112e-part1
> mdadm: clearing FAULTY flag for device 5 in /dev/md106 for 
> /dev/mapper/mpathid-350014ee056feaaf4-part1
> mdadm: clearing FAULTY flag for device 8 in /dev/md106 for 
> /dev/mapper/mpathid-350014ee001a93ede-part1
> mdadm: Marking array /dev/md106 as 'clean'
> mdadm: /dev/md106 assembled from 8 drives - not enough to start the array.
> 
> mdadm is wrong here: 8 devices is indeed the total number of devices for 
> this array.
> the last command started it inactive like this:
> 
> md106 : inactive dm-101[0](S) dm-24[9](S) dm-107[6](S) dm-103[5](S) 
> dm-123[4](S) dm-95[3](S) dm-105[2](S) dm-106[1](S)
>        4193255424 blocks super 1.2
> (maybe the blocks count is also wrong? Not adjusted for parity maybe? 
> 4193255424  / 8.0 * 6.0 == 3144941568.0 almost correct)
> 
> it can be fixed simply by doing:
> 
> root@storage1:/root# mdadm --stop /dev/md106
> mdadm: stopped /dev/md106
> 
> root@storage1:/root# mdadm --assemble /dev/md106 --config 
> /etc/mdadm/secondary.conf --no-degraded
> mdadm: /dev/md106 has been started with 8 drives.
> 
> now it works:
> 
> md106 : active raid6 dm-101[0] dm-24[9] dm-107[6] dm-103[5] dm-123[4] 
> dm-95[3] dm-105[2] dm-106[1]
>        3144938496 blocks super 1.2 level 6, 512k chunk, algorithm 2 
> [8/8] [UUUUUUUU]
>        bitmap: 0/1 pages [0KB], 1048576KB chunk
> 
> Regards
> EW
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Re: Very small bug on assemble --force

[Ethan Wilson]

On 28/10/2014 21:50, NeilBrown wrote:
> On Tue, 28 Oct 2014 15:27:02 +0100 Ethan Wilson <ethan.wilson@shiftmail.org>
> wrote:
>
>> Very small bug report:
> Thanks for the bug report.
> However, please always quote version of mdadm and version of Linux.
>
> I think this might have been fixed already, in mdadm 3.3.1.
>
> NeilBrown
>

Whops

kernel 3.14.22
mdadm - v3.2.5 - 18th May 2012

mdadm is old indeed so you are probably right.
It is difficult for me to test on the new version because I don't have 
degraded arrays anymore right now :-/
Sorry
EW