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Forum Discussion
mkfs.ext4 command parameters for 16tb+ volumes
On my ReadyNAS Pro recently, I had a problem with vertical expansion failing to work after replacing two drives with 3tb discs. After consulting over the course of a few weeks with support and finding a special-case bug, we (support and I) decided that the easiest path forward would be for me to just upgrade all of the drives to 3tb discs and do a factory reset, which would allow me to expand in the future. (They were more than willing to keep working on the issue to try to figure out why expand wasn't working...but I didn't want to take any more of their time if there was another route that would also solve the 16tb problem for me, and they agreed that this path would provide the most benefit for me).
However, after purchasing all 6 3tb drives and doing a factory reset with dual redundancy (18tb of drive space, but less after dual redundancy and overhead of course), I suspected that the underlying filesystem was not created (by the ReadyNAS) with the proper settings in order to allow me to expand past 16tb for the volume - dumpe2fs reports that the block size is still 4096.
I re-engaged support on this, trying to verify that after the factory reset with 6x3tb that I would be setup to go past 16tb volume size on a future drive swap. At first I was told that I would as long as I had FW 4.2.19 (which has the specialized fs tools supporting larger fs creation) - but later when I pointed out the blocksize I was informed that it wouldn't work the way we discussed, and that I should post on the forums to try to get the proper parameters.
So here I am. :-)
My plan is to do it in as follows:
#cd /
# tar cvf /tmp/c-backup.tar /c
# umount /c
# /sbin/mkfs.ext4 ?????
# mount -a
# tar xvf /tmp/c-backup.tar
...but all I need is for someone from Netgear to tell me what the "blessed" mkfs.ext4 parameters should be. :-)
(of course, if there are more steps needed, I'd love to know - but I'm hoping that the above is all I need).
Moving all my data off and back on again is the most time consuming part of the process - so I'd really prefer to make the ReadyNAS Pro's volume be 16tb+ compatible right now, while it is empty, before I spend days migrating data back on....in particular because it is just a quick mkfs/newfs command....and I'd prefer not to guess at parameters (block size of 8192 obviously - but the other parameters....). A couple of commands now will probably save days of downtime down the road when I get to the point of upgrading the drives.
Any help or suggestions would be much appreciated! Thanks!
However, after purchasing all 6 3tb drives and doing a factory reset with dual redundancy (18tb of drive space, but less after dual redundancy and overhead of course), I suspected that the underlying filesystem was not created (by the ReadyNAS) with the proper settings in order to allow me to expand past 16tb for the volume - dumpe2fs reports that the block size is still 4096.
I re-engaged support on this, trying to verify that after the factory reset with 6x3tb that I would be setup to go past 16tb volume size on a future drive swap. At first I was told that I would as long as I had FW 4.2.19 (which has the specialized fs tools supporting larger fs creation) - but later when I pointed out the blocksize I was informed that it wouldn't work the way we discussed, and that I should post on the forums to try to get the proper parameters.
So here I am. :-)
My plan is to do it in as follows:
#cd /
# tar cvf /tmp/c-backup.tar /c
# umount /c
# /sbin/mkfs.ext4 ?????
# mount -a
# tar xvf /tmp/c-backup.tar
...but all I need is for someone from Netgear to tell me what the "blessed" mkfs.ext4 parameters should be. :-)
(of course, if there are more steps needed, I'd love to know - but I'm hoping that the above is all I need).
Moving all my data off and back on again is the most time consuming part of the process - so I'd really prefer to make the ReadyNAS Pro's volume be 16tb+ compatible right now, while it is empty, before I spend days migrating data back on....in particular because it is just a quick mkfs/newfs command....and I'd prefer not to guess at parameters (block size of 8192 obviously - but the other parameters....). A couple of commands now will probably save days of downtime down the road when I get to the point of upgrading the drives.
Any help or suggestions would be much appreciated! Thanks!
2 Replies
- FYI, in looking at some other threads and man pages, the best I could come up with is
mkfs.ext4 -b 8192 -m 0 -E stride=16,stripe-width=64 -L c /dev/c/c
tune2fs -i0 -c -1 -o user_xattr,acl /dev/c/c
Also FYI, dumpe2fs /dev/c/c reports:Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent 64bit flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags: signed_directory_hash
Default mount options: user_xattr acl
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 182681600
Block count: 2922905600
Reserved block count: 0
Free blocks: 2911227511
Free inodes: 182681528
First block: 0
Block size: 4096
Fragment size: 4096
Reserved GDT blocks: 654
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 2048
Inode blocks per group: 128
RAID stride: 16
RAID stripe width: 64
Flex block group size: 16
Filesystem created: Tue Oct 11 22:31:07 2011
Last mount time: Wed Oct 12 13:06:08 2011
Last write time: Wed Oct 12 13:06:08 2011
Mount count: 5
Maximum mount count: -1
Last checked: Tue Oct 11 22:31:07 2011
Check interval: 0 (<none>)
Lifetime writes: 44 GB
Reserved blocks uid: 0 (user unknown)
Reserved blocks gid: 0 (group unknown)
First inode: 11
Inode size: 256
Required extra isize: 28
Desired extra isize: 28
Journal inode: 8
Default directory hash: half_md4
Journal backup: inode blocks
Journal features: journal_incompat_revoke
Journal size: 128M
Journal length: 32768
Journal sequence: 0x00000027
Journal start: 1 - FYI - I tried searching the filesystem for tools using the mkfs command, and I found one of the Frontview compiled Perl modules did so...but couldn't derive parameters from it (and it might just be for USB-attached drives instead of the primary array).
If there is something I could call from the command line to invoke the standard ReadyNAS modules/code to do this, all the better....
Any ideas? Thanks!
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