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[Paul Vinogradov <vin.public AT gmail.com>]

Thanks for such valuable description. What kernel version do you use? Does
grub2 support it fully? With /boot on btrfs?

В Sun, 27 May 2012 08:11:29 -0300
Ismael Luceno <ismael.luceno AT gmail.com> пишет:

> Hi, fellow mages. I would like to share my experience with btrfs.
> 
> To save some time, I've used a Debian Sid LiveCD. The whole process
> took about two hours. I'm not exactly sure how much, should have timed
> it.
> 
> The disk is a Hitachi HTS72757 750GB 7500RPM (real size 698GB)
> and the original filesystem was an ext4 of 690GB, of which 400GB were
> free space.
> 
> btrfs-convert itself took about an hour to convert the ext4 volume, and
> then resizing it to 590GB took about 30 minutes.
> 
> BTW, keep in mind that the brtfs tool doesn't report the limits of the
> filesystem, so it makes you guess. I think newer version of Gparted
> support brtfs (the annoying part of it is that always forces
> filesystem checks, and it's not a good idea in this case...).
> 
> I recovered about 20GB by deleting the ext2_saved volume. But it might
> come handy, so unless you have a full backup at hand, I would not
> recommend removing it.
> 
> Also, remember there's no fsck.brtfs (btrfsck is not production-ready),
> so you need to disable checking or provide a replacement for
> fsck.brtfs. 
> 
> I've moved all the grub stuff and kernels to another partition... I
> didn't feel like patching grub2. Backporting the module might be a good
> idea (or we could just borrow some other distro's work :P).
> 
> Also, before someone asks:
> 
>   ismael@pirotess:~$ df -h
>   /dev/sda1       592G  180G  270G  41% /
> 
>   ismael@pirotess:~$ btrfs fi df /
>   Data: total=395.00GB, used=125.92GB
>   System: total=32.00MB, used=36.00KB
>   Metadata: total=196.00GB, used=53.83GB
> 
> It might seem confusing, but what's happening is that btrfs is putting
> quite a lot of data along with the metadata, and it's not reporting the
> space reserved for metadata as free. The data-to-metadata ratio of 2:1
> makes it quite dramatic.
> 
> Looks like it behaves pretty well with small files. I'm not sure
> about big ones. Also I have concerns about filesystem images,
> databases, etc.
> 
> I noticed booting is slightly faster now, but I will not be sure
> how well it performs until defragmenting (since the migration doesn't
> leave it on an ideal shape).
> 
> That's all I guess :).


-- 
Sincerely yours Paul Vinogradov
E-mails: public AT sourcemage.org; vin.public AT gmail.com; pol-vinogradov AT mail.ru
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