btrfs defrag problem
Hi all,
I try to defrag my btrfs root partition (run by root privilege)
find / -type f -o -type d -print0 | xargs --null --no-run-if-empty btrfs filesystem defragment -t $((32*1024*1024))
1. This kind of error messages is prompted:
failed to open /bin/bash
open:: Text file busy
total 1 failures
failed to open /lib64/ld-2.15.so
open:: Text file busy
total 1 failures
failed to open /sbin/agetty
open:: Text file busy
failed to open /sbin/btrfs
open:: Text file busy
failed to open /sbin/dhclient
open:: Text file busy
failed to open /sbin/init
open:: Text file busy
failed to open /sbin/udevd
It seems that locked files cannot be defragged, is it expected behaviour?
2. Btrfs Wiki mentions that defrag directory will defrag metadata, is symlink/hardlink considered as metadata?
P.S. inline data is already disabled by "max_inline=0"
3. Is any possible to online defrag a btrfs partition without hindered by mount point/polyinstantied directories?
Thank you.
ching
Quoted 25 lines · ching
Hi all,
I try to defrag my btrfs root partition (run by root privilege)
find / -type f -o -type d -print0 | xargs --null --no-run-if-empty btrfs filesystem defragment -t $((32*1024*1024))
1. This kind of error messages is prompted:
failed to open
/bin/bash
open:: Text file busy
total 1 failures
failed to open/lib64/ld-2.15.so
open:: Text file busy
total 1 failures
failed to open/sbin/agetty
open:: Text file busy
failed to open/sbin/btrfs
open:: Text file busy
failed to open/sbin/dhclient
open:: Text file busy
failed to open/sbin/init
open:: Text file busy
failed to open/sbin/udevd
Quoted 1 line
It seems that locked files cannot be defragged, is it expected behaviour?
I can't reproduce that behaviour here, although maybe you're running an older kernel with some bug that's since been fixed?
Quoted 3 lines
2. Btrfs Wiki mentions that defrag directory will defrag metadata, is symlink/hardlink considered as metadata?
P.S. inline data is already disabled by "max_inline=0"
Well, that's a silly thing to do, causing every small file to take up a separate 4kb block rather than its size * 2, and requiring extra seeks to read/write them (i.e., if you have a million 10 byte files, they'll now take up 4GB instead of 20MB).
Quoted 1 line
3. Is any possible to online defrag a btrfs partition without hindered by mount point/polyinstantied directories?
If you're asking if you can defrag an unmounted btrfs, not at this time. It's possible in principle, nobody has cared enough to implement it yet.
Quoted 26 lines · cwillu
Quoted 25 lines · ching
Hi all,
I try to defrag my btrfs root partition (run by root privilege)
find / -type f -o -type d -print0 | xargs --null --no-run-if-empty btrfs filesystem defragment -t $((32*1024*1024))
1. This kind of error messages is prompted:
failed to open
/bin/bash
open:: Text file busy
total 1 failures
failed to open/lib64/ld-2.15.so
open:: Text file busy
total 1 failures
failed to open/sbin/agetty
open:: Text file busy
failed to open/sbin/btrfs
open:: Text file busy
failed to open/sbin/dhclient
open:: Text file busy
failed to open/sbin/init
open:: Text file busy
failed to open/sbin/udevd
Quoted 3 lines
Quoted 1 line
It seems that locked files cannot be defragged, is it expected behaviour?
I can't reproduce that behaviour here, although maybe you're running an older kernel with some bug that's since been fixed?
I am running Gentoo with Kernel 3.6.3 x64, btrfs-progs git version
my root is mounted with noatime,space_cache,inode_cache,metadata_ratio=15,max_inline=0,ssd_spread
Quoted 7 lines
Quoted 3 lines
2. Btrfs Wiki mentions that defrag directory will defrag metadata, is symlink/hardlink considered as metadata?
P.S. inline data is already disabled by "max_inline=0"Well, that's a silly thing to do, causing every small file to take up a separate 4kb block rather than its size * 2, and requiring extra seeks to read/write them (i.e., if you have a million 10 byte files, they'll now take up 4GB instead of 20MB).
this is off-topic to my question.
Quoted 5 lines
Quoted 1 line
3. Is any possible to online defrag a btrfs partition without hindered by mount point/polyinstantied directories?
If you're asking if you can defrag an unmounted btrfs, not at this time. It's possible in principle, nobody has cared enough to implement it yet.
Quoted 2 lines · ching
failed to open
/bin/bash
open:: Text file busy
That's not a btrfs problem, you can't directly modify an executable that is being used.
Quoted 6 lines
failed to open
/lib64/ld-2.15.so
failed to open/sbin/agetty
failed to open/sbin/btrfs
failed to open/sbin/dhclient
failed to open/sbin/init
failed to open/sbin/udevd
libraries, currently executed progs or daemons
Quoted 1 line
It seems that locked files cannot be defragged, is it expected behaviour?
Yes.
Quoted 2 lines
2. Btrfs Wiki mentions that defrag directory will defrag metadata, is symlink/hardlink considered as metadata?
P.S. inline data is already disabled by "max_inline=0"
Both -links are metadata and also stored inside metadata blocks without any chance to move to data blocks, so max_inline does not affect this.
Quoted 1 line
3. Is any possible to online defrag a btrfs partition without hindered by mount point/polyinstantied directories?
Sorry, I do not understand the question.
david
Quoted 3 lines
Quoted 2 lines
It seems that locked files cannot be defragged, is it expected behaviour?
Yes.
but i am defragging a file, not modify it.
Quoted 4 lines
Quoted 2 lines
2. Btrfs Wiki mentions that defrag directory will defrag metadata, is symlink/hardlink considered as metadata?
P.S. inline data is already disabled by "max_inline=0"Both -links are metadata and also stored inside metadata blocks without any chance to move to data blocks, so
max_inlinedoes not affect this.
thank you for your explanation.
Quoted 3 lines
Quoted 1 line
3. Is any possible to online defrag a btrfs partition without hindered by mount point/polyinstantied directories?
Sorry, I do not understand the question.
when a device is mounted under a directory, files in the directory is "hidden", and files in the device is "available", right? when a directory is polyinstantied, files in the original directory is "hidden", and files in the polyinstantied directory is "available",
How to get past them and pass those "hidden" files to defrag command?
ching
Quoted 7 lines · ching
Quoted 2 lines
Quoted 1 line
3. Is any possible to online defrag a btrfs partition without hindered by mount point/polyinstantied directories?
Sorry, I do not understand the question.
when a device is mounted under a directory, files in the directory is "hidden", and files in the device is "available", right? when a directory is polyinstantied, files in the original directory is "hidden", and files in the polyinstantied directory is "available",
How to get past them and pass those "hidden" files to defrag command?
I hope I get it right, so unless you have a reference to the directory with hidden files (using your term), there's no way to access them. And this is a more generic question, not related to btrfs itself. The hidden files may also belong to a different filesystem.
david
Quoted 6 lines · David Sterba
Quoted 5 lines · ching
Quoted 2 lines
Quoted 1 line
3. Is any possible to online defrag a btrfs partition without hindered by mount point/polyinstantied directories?
Sorry, I do not understand the question.
when a device is mounted under a directory, files in the directory is "hidden", and files in the device is "available", right? when a directory is polyinstantied, files in the original directory is "hidden", and files in the polyinstantied directory is "available",
Quoted 8 lines
Quoted 1 line
How to get past them and pass those "hidden" files to defrag command?
I hope I get it right, so unless you have a reference to the directory with hidden files (using your term), there's no way to access them. And this is a more generic question, not related to btrfs itself. The hidden files may also belong to a different filesystem.
david
thank for your explanation
ching
David Sterba wrote (ao):
Quoted 6 lines · ching
Quoted 5 lines
when a device is mounted under a directory, files in the directory is "hidden", and files in the device is "available", right? when a directory is polyinstantied, files in the original directory is "hidden", and files in the polyinstantied directory is "available",
Quoted 7 lines
Quoted 2 lines
How to get past them and pass those "hidden" files to defrag command?
I hope I get it right, so unless you have a reference to the directory with hidden files (using your term), there's no way to access them. And this is a more generic question, not related to btrfs itself. The hidden files may also belong to a different filesystem.
What Ching means (I think), is that if you have directories in /home, and you mount a device onto /home, you cannot see the original directories in /home anymore.
You can still access them though, with a 'mount -o bind':
# mount -o bind / /mnt # ls /mnt/home
Sander