* mdadm and size differences
@ 2015-11-24 10:32 Marco De Vitis
2015-12-21 2:32 ` NeilBrown
0 siblings, 1 reply; 2+ messages in thread
From: Marco De Vitis @ 2015-11-24 10:32 UTC (permalink / raw)
To: linux-raid
Hi,
I cannot understand a difference in size I can see on an old Debian 5.0
machine, maybe I'm just missing something obvious.
/dev/sdd is partitioned as follows, and /dev/sdf is exactly the same:
> #>fdisk -l /dev/sdd
>
> Disk /dev/sdd: 500.1 GB, 500107862016 bytes
> 255 heads, 63 sectors/track, 60801 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Disk identifier: 0x000901d8
>
> Device Boot Start End Blocks Id System
> /dev/sdd1 1 24 192748+ 83 Linux
> /dev/sdd2 25 60801 488191252+ 5 Extended
> /dev/sdd5 25 632 4883728+ 83 Linux
> /dev/sdd6 633 2982 18876343+ 83 Linux
> /dev/sdd7 2983 4199 9775521 83 Linux
> /dev/sdd8 4200 4807 4883728+ 83 Linux
> /dev/sdd9 4808 5173 2939863+ 82 Linux swap / Solaris
> /dev/sdd10 5174 31281 209712478+ 83 Linux
You can see that sdd6 is twice the size of sdd7.
cfdisk reports sizes of around 20 GB and 10 GB:
sdd6 -> 19329.41
sdd7 -> 10010.17
All partitions in these two identical drives are configured as RAID 1
using mdadm, but the md devices associated to sdd6/sdf6 and sdd7/sdf7
are both reported to be 10 GB in size, as can be seen from the mdadm
output below.
Why?
Thanks for any info.
> #>mdadm -vv --detail /dev/md2
> /dev/md2:
> Version : 00.90
> Creation Time : Thu Feb 22 16:18:11 2007
> Raid Level : raid1
> Array Size : 9767424 (9.31 GiB 10.00 GB)
> Used Dev Size : 9767424 (9.31 GiB 10.00 GB)
> Raid Devices : 2
> Total Devices : 2
> Preferred Minor : 2
> Persistence : Superblock is persistent
>
> Update Time : Mon Nov 23 14:19:23 2015
> State : clean
> Active Devices : 2
> Working Devices : 2
> Failed Devices : 0
> Spare Devices : 0
>
> UUID : 5582dad7:7ac89883:0c2b9e1d:5009dd35
> Events : 0.69228
>
> Number Major Minor RaidDevice State
> 0 8 54 0 active sync /dev/sdd6
> 1 8 86 1 active sync /dev/sdf6
>
> #>mdadm -vv --detail /dev/md3
> /dev/md3:
> Version : 00.90
> Creation Time : Thu Feb 22 16:18:54 2007
> Raid Level : raid1
> Array Size : 9767424 (9.31 GiB 10.00 GB)
> Used Dev Size : 9767424 (9.31 GiB 10.00 GB)
> Raid Devices : 2
> Total Devices : 2
> Preferred Minor : 3
> Persistence : Superblock is persistent
>
> Update Time : Mon Nov 23 14:19:27 2015
> State : clean
> Active Devices : 2
> Working Devices : 2
> Failed Devices : 0
> Spare Devices : 0
>
> UUID : e44836cf:6340f7fa:52fb3562:a78d4dbb
> Events : 0.187630
>
> Number Major Minor RaidDevice State
> 0 8 55 0 active sync /dev/sdd7
> 1 8 87 1 active sync /dev/sdf7
--
Ciao,
Marco.
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: mdadm and size differences
2015-11-24 10:32 mdadm and size differences Marco De Vitis
@ 2015-12-21 2:32 ` NeilBrown
0 siblings, 0 replies; 2+ messages in thread
From: NeilBrown @ 2015-12-21 2:32 UTC (permalink / raw)
To: Marco De Vitis, linux-raid
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On Tue, Nov 24 2015, Marco De Vitis wrote:
> Hi,
> I cannot understand a difference in size I can see on an old Debian 5.0
> machine, maybe I'm just missing something obvious.
...
>
> You can see that sdd6 is twice the size of sdd7.
> cfdisk reports sizes of around 20 GB and 10 GB:
> sdd6 -> 19329.41
> sdd7 -> 10010.17
>
> All partitions in these two identical drives are configured as RAID 1
> using mdadm, but the md devices associated to sdd6/sdf6 and sdd7/sdf7
> are both reported to be 10 GB in size, as can be seen from the mdadm
> output below.
>
> Why?
Probably because the arrays aren't using the whole partition.
e.g. if you have a RAID! comprised of 2 1GB partitions,
then you fail one partition and had a 2GB partition as a spare and let
it rebuild. Then fail the other 1GB partition and add a 3GB partition
as a spare and let it rebuild.
Then you will have a 1GB RAID made from 2 partitions, a 2GB partition
and a 3GB partition.
If you want to resize the RAID! to use all the available space, then use
the command
mdadm --grow /dev/md2 --size=max
You might then need to resize and filesystem you have in that array.
NeilBrown
>
> Thanks for any info.
>
>> #>mdadm -vv --detail /dev/md2
>> /dev/md2:
>> Version : 00.90
>> Creation Time : Thu Feb 22 16:18:11 2007
>> Raid Level : raid1
>> Array Size : 9767424 (9.31 GiB 10.00 GB)
>> Used Dev Size : 9767424 (9.31 GiB 10.00 GB)
>> Raid Devices : 2
>> Total Devices : 2
>> Preferred Minor : 2
>> Persistence : Superblock is persistent
>>
>> Update Time : Mon Nov 23 14:19:23 2015
>> State : clean
>> Active Devices : 2
>> Working Devices : 2
>> Failed Devices : 0
>> Spare Devices : 0
>>
>> UUID : 5582dad7:7ac89883:0c2b9e1d:5009dd35
>> Events : 0.69228
>>
>> Number Major Minor RaidDevice State
>> 0 8 54 0 active sync /dev/sdd6
>> 1 8 86 1 active sync /dev/sdf6
>>
>> #>mdadm -vv --detail /dev/md3
>> /dev/md3:
>> Version : 00.90
>> Creation Time : Thu Feb 22 16:18:54 2007
>> Raid Level : raid1
>> Array Size : 9767424 (9.31 GiB 10.00 GB)
>> Used Dev Size : 9767424 (9.31 GiB 10.00 GB)
>> Raid Devices : 2
>> Total Devices : 2
>> Preferred Minor : 3
>> Persistence : Superblock is persistent
>>
>> Update Time : Mon Nov 23 14:19:27 2015
>> State : clean
>> Active Devices : 2
>> Working Devices : 2
>> Failed Devices : 0
>> Spare Devices : 0
>>
>> UUID : e44836cf:6340f7fa:52fb3562:a78d4dbb
>> Events : 0.187630
>>
>> Number Major Minor RaidDevice State
>> 0 8 55 0 active sync /dev/sdd7
>> 1 8 87 1 active sync /dev/sdf7
>
> --
> Ciao,
> Marco.
>
> --
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