On Fri, 2014-01-10 at 19:52 +0000, Mathias Burén wrote:
> On 10 January 2014 18:12, Wilson Jonathan <piercing_male@xxxxxxxxxxx> wrote:
> > On Fri, 2014-01-10 at 17:36 +0000, Mathias Burén wrote:
> >> Hi all,
> >>
> >> I've a device that's part of an MD array:
> >>
> >> fdisk
> >> Disk /dev/sdg: 3000.6 GB, 3000592982016 bytes
> >> 255 heads, 63 sectors/track, 364801 cylinders, total 5860533168 sectors
> >> Units = sectors of 1 * 512 = 512 bytes
> >> Sector size (logical/physical): 512 bytes / 4096 bytes
> >> I/O size (minimum/optimal): 4096 bytes / 4096 bytes
> >> Disk identifier: 0x00000000
> >>
> >> $ sudo mdadm -E /dev/sdg
> >> /dev/sdg:
> >> Magic : a92b4efc
> >> Version : 1.2
> >> Feature Map : 0x0
> >> Array UUID : 0ad2603e:e43283ee:02180773:98e716ef
> >> Name : ion:md0 (local to host ion)
> >> Creation Time : Tue Feb 5 17:33:27 2013
> >> Raid Level : raid6
> >> Raid Devices : 6
> >>
> >> Avail Dev Size : 5860271024 (2794.40 GiB 3000.46 GB)
> >> Array Size : 7813531648 (7451.56 GiB 8001.06 GB)
> >> Used Dev Size : 3906765824 (1862.89 GiB 2000.26 GB)
> >> Data Offset : 262144 sectors
> >> Super Offset : 8 sectors
> >> State : clean
> >> Device UUID : 39c0b717:a9ca1dd7:bcba618f:caed0879
> >>
> >> Update Time : Fri Jan 10 17:28:31 2014
> >> Checksum : 53ea0170 - correct
> >> Events : 2668
> >>
> >> Layout : left-symmetric
> >> Chunk Size : 512K
> >>
> >> Device Role : Active device 4
> >> Array State : AAAAAA ('A' == active, '.' == missing)
> >>
> >> As you can see, Used Dev Size is lower than Avail Dev Size. Can I use
> >> the unallocated space by MD for storage somehow? As the devices in the
> >> array are used fully (no partitions) I guess not, but perhaps there is
> >> a way.
> >>
> >
> > I'm wondering, did you perhaps add a drive after the initial creation
> > and forgot to grow the array to use the additional space? I believe that
> > adding a drive after creation causes the raid to spread the data over
> > all the drives via (I think) a re-shape which then needs a "grow" to
> > then extend to the end of the drives.
> >
> > Actually thinking about it, 8GB would equate to 4 drives of 2TB each and
> > 2 for redundancy = 6 drives total as noted in your post... is one of the
> > drives a 2 tb by mistake which would cause the 3tb drives to be limited
> > to the first 2tb... if they are all 3tb then I believe a grow=max size
> > (You'll need to double check the man page) should then use the un-used
> > space which will mean your array size should increase to 12TB (4*3TB+2
> > redundancy)
> >
> >> Regards,
> >> Mathis
> >
> > Jon.
> >
> >
>
> Doh,
>
> Of course, I forgot ti add; the array is using 6x 2TB drives and 1x
> 3TB drive, for a total of 7 drives in a RAID6. It's the single 3TB
> drive that I'm wondering about, if I can use the space not used by MD
> on it.
>
> Mathias
>
In that case the answer would be no. However if fail/remove the 3TB
drive, then partitioned the drive as 2TB and 1TB and then added the 2TB
partition back into the array then you can use the 1TB on its own...
just as long the "2TB" partition is the same size as the 2TB drives (or
slightly bigger) then it should all work nicely.
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