Re: [PLUG] Growing a RAID 5 (sorry about the missend)

["Rich Mingin \(PLUG\) via plug" <plug@lists.phillylinux.org>]

As Rich Prime noted, your array is currently reshaping. When it is done, the total space will update. This can take a day or more. Any writes to the array will write the new stripe width, so it won’t impact reshape speed much, but I’d avoid unnecessary I/O to the array while it is working. I did not know that 1+1 RAID5 was valid. That’s interesting.

On Thu, Dec 16, 2021 at 18:33 Martin Cracauer via plug <plug@lists.phillylinux.org> wrote:

Can you post /dev/mdstat please?

Just to clarify what you are trying to do here:
- you have a degraded but online 2-disk raid5 of net 1 TB
- you want to add 1 drive to make it a non-degraded net 1 TB
- then you want to add another drive to make it net 2 TB

?

Martin

Adam Zion via plug wrote on Thu, Dec 16, 2021 at 05:43:27PM -0500:
> Let's try that again...
>
> I had a 1 TB RAID 5 consisting of 2 1TB drives (yes, that works). To double
> its capacity, I purchased two more 1TB drives. They were mounted as /dev/sdc
> and /dev/sdd, and I created an ext4 partition on each so that I had /dev/sdc1
> and /dev/sdd1.
>
> Then, I needed to issue commands to grow the RAID. I did as follows:
>
> sudo --grow --raid-devices=4 /dev/md0
> and
> sudo mdadm --grow --raid-devices=4 /dev/md0
>
> I had expected that the second command would take a LONG time to complete.
> But, it seemed to finish in <1 min. Now, sudo mdadm --detail /dev/md0
> yields the following:
>
> /dev/md0:
>            Version : 1.2
>      Creation Time : Thu Dec  9 23:50:04 2021
>         Raid Level : raid5
>         Array Size : 976627712 (931.38 GiB 1000.07 GB)
>      Used Dev Size : 976627712 (931.38 GiB 1000.07 GB)
>       Raid Devices : 4
>      Total Devices : 4
>        Persistence : Superblock is persistent
>
>      Intent Bitmap : Internal
>
>        Update Time : Thu Dec 16 22:40:07 2021
>              State : clean, reshaping
>     Active Devices : 4
>    Working Devices : 4
>     Failed Devices : 0
>      Spare Devices : 0
>
>             Layout : left-symmetric
>         Chunk Size : 512K
>
> Consistency Policy : bitmap
>
>     Reshape Status : 0% complete
>      Delta Devices : 2, (2->4)
>
>               Name : home-nas:0  (local to host home-nas)
>               UUID : 41dcee9c:5feb3a19:d1d7ce0e:905f749d
>             Events : 12742
>
>     Number   Major   Minor   RaidDevice State
>        0       8       17        0      active sync   /dev/sdb1
>        2       8        1        1      active sync   /dev/sda1
>        4       8       49        2      active sync   /dev/sdd1
>        3       8       33        3      active sync   /dev/sdc1
>
> Obviously, from the array size at the top, this has not completed adding
> the new drives to the RAID. But, at the bottom, mdadm clearly shows that it
> *has* done so.
>
> Thoughts?
>
> --
> Adam+Zion, MSIS
> Registered Linux User #471910
> http://www.adamzion.com <http://www.linkedin.com/in/azion1995>

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Martin Cracauer <cracauer@cons.org>   http://www.cons.org/cracauer/
___________________________________________________________________________
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___________________________________________________________________________
Philadelphia Linux Users Group         --        http://www.phillylinux.org
Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
General Discussion  --   http://lists.phillylinux.org/mailman/listinfo/plug