Grow on RAID10 does work. Here is my previous attempt at trying to
change --raid-devices and -p separately.
# mdadm --detail /dev/md13
/dev/md13:
Version : 1.2
Creation Time : Wed Nov 2 11:25:22 2016
Raid Level : raid10
Array Size : 10477568 (9.99 GiB 10.73 GB)
Used Dev Size : 10477568 (9.99 GiB 10.73 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Wed Nov 2 11:25:22 2016
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Layout : near=2
Chunk Size : 512K
Name : rleblanc-pc:13 (local to host rleblanc-pc)
UUID : 278c5e33:5ac1d25a:241a0cf7:66269542
Events : 0
Number Major Minor RaidDevice State
0 7 2 0 active sync set-A /dev/loop2
1 7 3 1 active sync set-B /dev/loop3
# mdadm /dev/md13 -a /dev/loop4
mdadm: added /dev/loop4
root@rleblanc-pc:/home/rleblanc/Downloads# mdadm --detail /dev/md13
/dev/md13:
Version : 1.2
Creation Time : Wed Nov 2 11:25:22 2016
Raid Level : raid10
Array Size : 10477568 (9.99 GiB 10.73 GB)
Used Dev Size : 10477568 (9.99 GiB 10.73 GB)
Raid Devices : 2
Total Devices : 3
Persistence : Superblock is persistent
Update Time : Wed Nov 2 11:27:33 2016
State : clean
Active Devices : 2
Working Devices : 3
Failed Devices : 0
Spare Devices : 1
Layout : near=2
Chunk Size : 512K
Name : rleblanc-pc:13 (local to host rleblanc-pc)
UUID : 278c5e33:5ac1d25a:241a0cf7:66269542
Events : 1
Number Major Minor RaidDevice State
0 7 2 0 active sync set-A /dev/loop2
1 7 3 1 active sync set-B /dev/loop3
2 7 4 - spare /dev/loop4
# mdadm --grow /dev/md13 --raid-devices 3
# mdadm --detail /dev/md13
/dev/md13:
Version : 1.2
Creation Time : Wed Nov 2 11:25:22 2016
Raid Level : raid10
Array Size : 10477568 (9.99 GiB 10.73 GB)
Used Dev Size : 10477568 (9.99 GiB 10.73 GB)
Raid Devices : 3
Total Devices : 3
Persistence : Superblock is persistent
Update Time : Wed Nov 2 11:28:08 2016
State : clean, reshaping
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Layout : near=2
Chunk Size : 512K
Reshape Status : 1% complete
Delta Devices : 1, (2->3)
Name : rleblanc-pc:13 (local to host rleblanc-pc)
UUID : 278c5e33:5ac1d25a:241a0cf7:66269542
Events : 12
Number Major Minor RaidDevice State
0 7 2 0 active sync /dev/loop2
1 7 3 1 active sync /dev/loop3
2 7 4 2 active sync /dev/loop4
----Wait for reshape to finish----
# mdadm --detail /dev/md13
/dev/md13:
Version : 1.2
Creation Time : Wed Nov 2 11:25:22 2016
Raid Level : raid10
Array Size : 15716352 (14.99 GiB 16.09 GB)
Used Dev Size : 10477568 (9.99 GiB 10.73 GB)
Raid Devices : 3
Total Devices : 3
Persistence : Superblock is persistent
Update Time : Wed Nov 2 11:33:25 2016
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Layout : near=2
Chunk Size : 512K
Name : rleblanc-pc:13 (local to host rleblanc-pc)
UUID : 278c5e33:5ac1d25a:241a0cf7:66269542
Events : 49
Number Major Minor RaidDevice State
0 7 2 0 active sync /dev/loop2
1 7 3 1 active sync /dev/loop3
2 7 4 2 active sync /dev/loop4
# mdadm --grow /dev/md13 -p n3
mdadm: Cannot change number of copies when reshaping RAID10
----------------
Robert LeBlanc
PGP Fingerprint 79A2 9CA4 6CC4 45DD A904 C70E E654 3BB2 FA62 B9F1
On Wed, Nov 2, 2016 at 12:09 PM, Wols Lists <antlists@xxxxxxxxxxxxxxx> wrote:
> On 02/11/16 17:59, Robert LeBlanc wrote:
>> We would like to add read performance to our RAID10 volume by adding
>> another drive (we don't care about space), so I did the following test
>> with poor results.
>
> Quicky reply ...
>
> I don't think you can change the number of raid-devices on a raid10. Are
> you trying to replace a slow drive with a faster one? You can probably
> use the --replace option.
>
> If not that, what do you want to achieve?
>
> Cheers,
> Wol
>
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