* off-line resizing?
@ 2012-06-13 16:06 Ivan Shmakov
[not found] ` <86fw9zw601.fsf-Sxm0eyAyORm7AG94EA9mQA@public.gmane.org>
0 siblings, 1 reply; 5+ messages in thread
From: Ivan Shmakov @ 2012-06-13 16:06 UTC (permalink / raw)
To: linux-nilfs-u79uwXL29TY76Z2rM5mHXA
The FAQ reads:
--cut: http://www.nilfs.org/en/faq.html --
5. Can I resize NILFS volumes ?
Yes, you can both enlarge and shrink NILFS volumes with
nilfs-resize command. This feature is available on Linux 3.0 and
later. Resizing for unmounted file systems are not supported at
present.
For details, please see the man page of nilfs-resize(8).
--cut: http://www.nilfs.org/en/faq.html --
Unfortunately, I don't plan to switch my “production” hosts to
Linux 3 yet. However, for the purposes I want to give NILFS a
try I can assume that I can easily umount the volume whenever I
need to resize it, to run whatever user-space code necessary.
Thus, I'm curious, are there any plans to implement “off-line”
NILFS resizing?
TIA.
--
FSF associate member #7257 np. Дождь — ДДТ
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: off-line resizing?
[not found] ` <86fw9zw601.fsf-Sxm0eyAyORm7AG94EA9mQA@public.gmane.org>
@ 2012-06-14 2:06 ` Ryusuke Konishi
2012-06-14 4:22 ` Ivan Shmakov
0 siblings, 1 reply; 5+ messages in thread
From: Ryusuke Konishi @ 2012-06-14 2:06 UTC (permalink / raw)
To: oneingray-Re5JQEeQqe8AvxtiuMwx3w; +Cc: linux-nilfs-u79uwXL29TY76Z2rM5mHXA
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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Hi,
On Wed, 13 Jun 2012 23:06:54 +0700, Ivan Shmakov wrote:
> The FAQ reads:
>
> --cut: http://www.nilfs.org/en/faq.html --
> 5. Can I resize NILFS volumes ?
>
> Yes, you can both enlarge and shrink NILFS volumes with
> nilfs-resize command. This feature is available on Linux 3.0 and
> later. Resizing for unmounted file systems are not supported at
> present.
>
> For details, please see the man page of nilfs-resize(8).
> --cut: http://www.nilfs.org/en/faq.html --
>
> Unfortunately, I don't plan to switch my âproductionâ hosts to
> Linux 3 yet. However, for the purposes I want to give NILFS a
> try I can assume that I can easily umount the volume whenever I
> need to resize it, to run whatever user-space code necessary.
>
> Thus, I'm curious, are there any plans to implement âoff-lineâ
> NILFS resizing?
>
> TIA.
Implementing Off-line resizing is a bit tough task because it requires
a user space library to read internal meta data of the nilfs file
system and append updated blocks to it. This is almost equivalent to
implementing kernel functions of nilfs in user land.
So, we have no concrete schedule now.
If you are using RHEL6 or its clones, however, standalone kernel
modules supporting online-resizing are available from:
http://www.nilfs.org/en/pkg_centos.html.
For other Linux distros, the standalone kmod may be applicable with or
without customizing the source code. it has a glue code to support
multiple kernel versions. For reference, the source code of the
standalone kmod is available at:
git://github.com/nilfs-dev/nilfs2-kmod-centos6.git
With regards,
Ryusuke Konishi
> --
> FSF associate member #7257 np. ÐÐ¾Ð¶Ð´Ñ â ÐÐТ
>
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: off-line resizing?
2012-06-14 2:06 ` Ryusuke Konishi
@ 2012-06-14 4:22 ` Ivan Shmakov
[not found] ` <86lijqv7ye.fsf-Sxm0eyAyORm7AG94EA9mQA@public.gmane.org>
0 siblings, 1 reply; 5+ messages in thread
From: Ivan Shmakov @ 2012-06-14 4:22 UTC (permalink / raw)
To: linux-nilfs-u79uwXL29TY76Z2rM5mHXA
>>>>> Ryusuke Konishi writes:
>>>>> On Wed, 13 Jun 2012 23:06:54 +0700, Ivan Shmakov wrote:
[…]
>> Unfortunately, I don't plan to switch my “production” hosts to Linux
>> 3 yet. However, for the purposes I want to give NILFS a try I can
>> assume that I can easily umount the volume whenever I need to resize
>> it, to run whatever user-space code necessary.
>> Thus, I'm curious, are there any plans to implement “off-line” NILFS
>> resizing?
> Implementing Off-line resizing is a bit tough task because it
> requires a user space library to read internal meta data of the nilfs
> file system and append updated blocks to it. This is almost
> equivalent to implementing kernel functions of nilfs in user land.
> So, we have no concrete schedule now.
ACK, thanks.
I wonder, how complicated this task would be? In particular, do
I need to alter all the segments to resize filesystem, or only
specific ones? Also, are these internal metadata records just
“a bunch of C structs”, or something more complex?
[…]
> For other Linux distros, the standalone kmod may be applicable with
> or without customizing the source code. it has a glue code to
> support multiple kernel versions. For reference, the source code of
> the standalone kmod is available at:
> git://github.com/nilfs-dev/nilfs2-kmod-centos6.git
ACK, thanks.
--
FSF associate member #7257
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: off-line resizing?
[not found] ` <86lijqv7ye.fsf-Sxm0eyAyORm7AG94EA9mQA@public.gmane.org>
@ 2012-06-16 1:15 ` Ryusuke Konishi
2012-06-17 15:44 ` user-level toolkit for off-line operations Ivan Shmakov
0 siblings, 1 reply; 5+ messages in thread
From: Ryusuke Konishi @ 2012-06-16 1:15 UTC (permalink / raw)
To: oneingray-Re5JQEeQqe8AvxtiuMwx3w; +Cc: linux-nilfs-u79uwXL29TY76Z2rM5mHXA
On Thu, 14 Jun 2012 11:22:17 +0700, Ivan Shmakov wrote:
> >>>>> Ryusuke Konishi writes:
> >>>>> On Wed, 13 Jun 2012 23:06:54 +0700, Ivan Shmakov wrote:
> >> Thus, I'm curious, are there any plans to implement “off-line” NILFS
> >> resizing?
>
> > Implementing Off-line resizing is a bit tough task because it
> > requires a user space library to read internal meta data of the nilfs
> > file system and append updated blocks to it. This is almost
> > equivalent to implementing kernel functions of nilfs in user land.
>
> > So, we have no concrete schedule now.
>
> ACK, thanks.
>
> I wonder, how complicated this task would be? In particular, do
> I need to alter all the segments to resize filesystem, or only
> specific ones? Also, are these internal metadata records just
> “a bunch of C structs”, or something more complex?
This needs at least the following tasks:
1) Update two super blocks to increase/decrease the number of total
segments and the device size. (easy)
2) Update segment usage information to adjust free segment count of
nilfs_sufile_header struct (sh_ncleansegs) which is written in
the segment usage file. (Sadly not easy)
3) If truncating in-use segments, relocating blocks and updating
disk address translation information are also needed. (very hard)
For reference, a discussion on this topic is found in the archives of
the list:
http://marc.info/?t=128419843600003&r=1&w=2
Regards,
Ryusuke Konishi
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^ permalink raw reply [flat|nested] 5+ messages in thread
* user-level toolkit for off-line operations
2012-06-16 1:15 ` Ryusuke Konishi
@ 2012-06-17 15:44 ` Ivan Shmakov
0 siblings, 0 replies; 5+ messages in thread
From: Ivan Shmakov @ 2012-06-17 15:44 UTC (permalink / raw)
To: linux-nilfs-u79uwXL29TY76Z2rM5mHXA
>>>>> Ryusuke Konishi writes:
>>>>> On Thu, 14 Jun 2012 11:22:17 +0700, Ivan Shmakov wrote:
>>>>> Ryusuke Konishi writes:
[…]
>>> Implementing Off-line resizing is a bit tough task because it
>>> requires a user space library to read internal meta data of the
>>> nilfs file system and append updated blocks to it.
… I guess that a user-level toolkit akin to e2fsprogs would be
handy anyway. (Shouldn't there be an fsck(8) for NILFS, BTW?)
Other than resizing, there could be a feature to “split” a
filesystem — take one or more “snapshot” checkpoints and make a
copy of the parts of the filesystem “reachable” from these
checkpoints on a distinct block device (perhaps of a differing
size), which seems like one more way to do backups.
>>> This is almost equivalent to implementing kernel functions of nilfs
>>> in user land.
[…]
>> I wonder, how complicated this task would be? In particular, do I
>> need to alter all the segments to resize filesystem, or only
>> specific ones? Also, are these internal metadata records just “a
>> bunch of C structs”, or something more complex?
> This needs at least the following tasks:
> 1) Update two super blocks to increase/decrease the number of total
> segments and the device size. (easy)
> 2) Update segment usage information to adjust free segment count of
> nilfs_sufile_header struct (sh_ncleansegs) which is written in
> the segment usage file. (Sadly not easy)
> 3) If truncating in-use segments, relocating blocks and updating disk
> address translation information are also needed. (very hard)
ACK. (Fortunately, I'm not that interested in shrinking
filesystems right now.)
> For reference, a discussion on this topic is found in the archives of
> the list:
> http://marc.info/?t=128419843600003&r=1&w=2
ACK, thanks! I hope to take a closer look at this problem
within two weeks or so.
(JFTR: those reading via Gmane may access the thread via either
of [1, 2]; the first message in the thread is [3].)
[1] http://comments.gmane.org/gmane.comp.file-systems.nilfs.user/397
[2] http://thread.gmane.org/gmane.comp.file-systems.nilfs.user/397/focus=1686
[3] news:BAEFA5609CC3AB4BAE1625CAD4C27E5C02986E1D-qPLjlnsG5hmCmmEZ8mJCX7uPtZ6Ynr+y@public.gmane.orga.com
--
FSF associate member #7257
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^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2012-06-17 15:44 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-06-13 16:06 off-line resizing? Ivan Shmakov
[not found] ` <86fw9zw601.fsf-Sxm0eyAyORm7AG94EA9mQA@public.gmane.org>
2012-06-14 2:06 ` Ryusuke Konishi
2012-06-14 4:22 ` Ivan Shmakov
[not found] ` <86lijqv7ye.fsf-Sxm0eyAyORm7AG94EA9mQA@public.gmane.org>
2012-06-16 1:15 ` Ryusuke Konishi
2012-06-17 15:44 ` user-level toolkit for off-line operations Ivan Shmakov
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