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Re: [linux-lvm] Q: Online resizing ext3 FS



Chris Osicki schrieb:
Hi

I apologize in advance for asking a question not really appropriate
for this mailing list, but I couldn't find a better place with lots of
people managing lots of disk space.
The question:
Has anyone of you been using ext2online to resize (large) ext3 filesystems?
I have to do it going from 500GB to 1TB on a productive system I was
wondering if you have some horror/success stories.
I'm using RHEL4/U4 (kernel 2.6.9) on this system.

Yes, I tried to online resize a similar filesystem (600 MB to 1.2 TB) and it didn't work.

At some point, resize2fs would just exit with errors.
I tried to do it several times before I figured out what's missing; sometimes, I interrupted the process with ctrl+c. No data loss occurred.

To do an online ext3 resize, the filesystem needs a "resize_inode" feature. You can check the features with dumpe2fs:

# dumpe2fs -h /dev/sda1
(...)
Filesystem features: has_journal resize_inode dir_index filetype needs_recovery sparse_super large_file
(...)

This flag is added by default only in the recent versions of e2progs (1.39 and later AFAIR); before, it had to be specified manually. So with RHEL4, you may be out of luck.


In the end, I had to to an offline resize.


I had this volume mirrored on another machine, so I didn't worry that much though.


Also, to resize a filesystem of that size you would need plenty of RAM (if you have about 1 GB RAM free, it should be just enough; otherwise, your machine will be swapping, and the process will take longer). Before, I tried to resize it on a machine with 256 MB and several snapshots; resize2fs was killed because of OOM, and still, no data loss.


If you have that an old kernel, take care if you're using snapshots; I believe they are stable only as of 2.6.22 (before 2.6.22 snapshots needed a lot of RAM; before 2.6.18 there were problems with snapshots removing etc.).


Would be good to add some of that info to LVM HOWTO.


--
Tomasz Chmielewski
http://wpkg.org


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