Bug 1164494 - mdadm --grow --size does not work for >2TB
Summary: mdadm --grow --size does not work for >2TB
Keywords:
Status: CLOSED EOL
Alias: None
Product: Fedora
Classification: Fedora
Component: mdadm
Version: 22
Hardware: x86_64
OS: Linux
unspecified
medium
Target Milestone: ---
Assignee: XiaoNi
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks: 1236538
TreeView+ depends on / blocked
 
Reported: 2014-11-15 20:14 UTC by Jon Burgess
Modified: 2016-07-19 19:31 UTC (History)
4 users (show)

Fixed In Version:
Clone Of:
: 1236538 (view as bug list)
Environment:
Last Closed: 2016-07-19 19:31:42 UTC
Type: Bug
Embargoed:


Attachments (Terms of Use)
output from mdstat, mdadm, partitions, kernel etc (7.57 KB, text/plain)
2014-11-15 20:14 UTC, Jon Burgess
no flags Details

Description Jon Burgess 2014-11-15 20:14:48 UTC
Created attachment 957867 [details]
output from mdstat, mdadm, partitions, kernel etc

Description of problem:

When using mdadm to grow or shrink a RAID1 array to a fixed size beyond 2TB the request is ignored. If 'max' is used then the full 3TB size is correctly set.

Version-Release number of selected component (if applicable):

mdadm-3.3-7.fc20.x86_64
kernel-3.17.2-200.fc20.x86_64

How reproducible:

every time for any size > 2TB

Steps to Reproduce:
1. RAID1 with 2 x 3TB disks, each with single partition (sdb1, sdc1)
2. Setting size to 'max' results in a 3TB array
3. Trying to set any size between 2 & 3TB is ignored
4. Setting sizes < 2TB works

Actual results:

[root@shark ~]# mdadm /dev/md0 --grow --size=max
mdadm: component size of /dev/md0 has been set to 2930134016K

[root@shark ~]# cat /proc/mdstat
Personalities : [raid1] 
md0 : active raid1 sdc1[3] sdb1[2]
      2930134016 blocks super 1.2 [2/2] [UU]

[root@shark ~]# mdadm /dev/md0 --grow --size=2900000000
mdadm: component size of /dev/md0 unchanged at 2930134016K

[root@shark ~]# mdadm /dev/md0 --grow --size=2147483647
mdadm: component size of /dev/md0 has been set to 2147483647K

[root@shark ~]# mdadm /dev/md0 --grow --size=2900000000
mdadm: component size of /dev/md0 unchanged at 2147483647K

Expected results:

Setting any size value less than the 'max' should work. Using a size slightly less than the max is useful in case a future drive replacement is slightly smaller (as recommended in man page).

Additional info:

Using strace suggests that mdadm is probably not at fault, more likely this is a kernel md issue. mdadm seems to write the correct values into the /sys files but the kernel ignores them, e.g. setting 2.9TB:

open("/sys/block/md0/md/dev-sdc1/size", O_WRONLY) = 4
write(4, "2900000000", 10)              = 10
...
open("/sys/block/md0/md/component_size", O_RDONLY) = 4
read(4, "2147483647\n", 50)             = 11

When the array was first created several years ago it contained 2 x 1.5 TB disks. These were replaced with the current 3TB disks.

A selection of data from /proc/mdstat, mdadm --examine, /proc/partitions, kernel etc. are attached.

Comment 1 Fedora End Of Life 2015-05-29 13:18:34 UTC
This message is a reminder that Fedora 20 is nearing its end of life.
Approximately 4 (four) weeks from now Fedora will stop maintaining
and issuing updates for Fedora 20. It is Fedora's policy to close all
bug reports from releases that are no longer maintained. At that time
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Comment 8 Fedora End Of Life 2015-06-29 23:19:22 UTC
Fedora 20 changed to end-of-life (EOL) status on 2015-06-23. Fedora 20 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.

If you can reproduce this bug against a currently maintained version of
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Comment 9 Fedora End Of Life 2016-07-19 19:31:42 UTC
Fedora 22 changed to end-of-life (EOL) status on 2016-07-19. Fedora 22 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.

If you can reproduce this bug against a currently maintained version of
Fedora please feel free to reopen this bug against that version. If you
are unable to reopen this bug, please file a new report against the
current release. If you experience problems, please add a comment to this
bug.

Thank you for reporting this bug and we are sorry it could not be fixed.


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