Re: btrfs defrag problem

[ching <lsching17@gmail.com>]

On 10/30/2012 08:08 PM, cwillu wrote:
> On Tue, Oct 30, 2012 at 5:47 AM, ching <lsching17@gmail.com> wrote:
>> 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?
> 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


>> 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.

>> 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.
>