On Sat, 13 Oct 2007, Marko Berg wrote:
Bill Davidsen wrote:
Marko Berg wrote:
I added a fourth drive to a RAID 5 array. After some complications related
to adding a new HD controller at the same time, and thus changing some
device names, I re-created the array and got it working (in the sense
"nothing degraded"). But size results are weird. Each component partition
is 320 G, does anyone have an explanation for the "Used Dev Size" field
value below? The 960 G total size is as it should be, but in practice
Linux reports the array only having 625,019,608 blocks.
I don't see that number below, what command reported this?
For instance df:
$ df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/md0 625019608 358223356 235539408 61% /usr/pub
How can this be, even though the array should be clean with 4 active
devices?
$ mdadm -D /dev/md0
/dev/md0:
Version : 01.02.03
Creation Time : Sat Oct 13 01:25:26 2007
Raid Level : raid5
Array Size : 937705344 (894.27 GiB 960.21 GB)
Used Dev Size : 625136896 (298.09 GiB 320.07 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Sat Oct 13 05:11:38 2007
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 64K
Name : 0
UUID : 9bf903f8:7fc9eec1:2ff25011:37e9607b
Events : 2
Number Major Minor RaidDevice State
0 253 2 0 active sync
/dev/VolGroup01/LogVol02
1 8 33 1 active sync /dev/sdc1
2 8 49 2 active sync /dev/sdd1
3 8 17 3 active sync /dev/sdb1
Results for mdadm -E <partition> on all devices appear like this one, with
positions changed:
$ mdadm -E /dev/sdc1
/dev/sdc1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 9bf903f8:7fc9eec1:2ff25011:37e9607b
Name : 0
Creation Time : Sat Oct 13 01:25:26 2007
Raid Level : raid5
Raid Devices : 4
Used Dev Size : 625137010 (298.09 GiB 320.07 GB)
Array Size : 1875410688 (894.27 GiB 960.21 GB)
Used Size : 625136896 (298.09 GiB 320.07 GB)
Data Offset : 272 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 9b2037fb:231a8ebf:1aaa5577:140795cc
Update Time : Sat Oct 13 10:56:02 2007
Checksum : c729f5a1 - correct
Events : 2
Layout : left-symmetric
Chunk Size : 64K
Array Slot : 1 (0, 1, 2, 3)
Array State : uUuu
Particularly, "Used Dev Size" and "Used Size" report an amount twice the
size of the partition (and device). Array size is here twice the actual
size, even though shown correctly within parentheses.
Sectors are 512 bytes.
So "Used Dev Size" above uses sector size, while "Array Size" uses 1k blocks?
I'm pretty sure, though, that previously "Used Dev Size" was in 1k blocks
too. That's also what most of the examples in the net seem to have.
Finally, mdstat shows the block count as it should be.
$ cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdb1[3] sdd1[2] sdc1[1] dm-2[0]
937705344 blocks super 1.2 level 5, 64k chunk, algorithm 2 [4/4]
[UUUU]
unused devices: <none>
Any suggestions on how to fix this, or what to investigate next, would be
appreciated!
I'm not sure what you're trying to "fix" here, everything you posted looks
sane.
I'm trying to find the missing 300 GB that, as df reports, are not available.
I ought to have a 900 GB array, consisting of four 300 GB devices, while only
600 GB are available. Adding the fourth device didn't increase the capacity
of the array (visible, at least). E.g. fdisk reports the array size to be 900
G, but df still claims 600 capacity. Any clues why?
--
Marko
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You have to expand the filesystem.
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