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
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