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UX.MAN
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PostPosted: Thu Sep 19, 2013 7:14 pm    Post subject: BTRFS features discussion Reply with quote

I'm starting this thread to discuss the current state and usage of BTRFS.

BTRFS brought my attention when I read about the native RAID feature. I'm currently running my filesystem structure this way:

Code:

  DM-crypt
     |
    LVM
     |
   EXT4


The RAID integrated feature of BTRFS will allow me to dismiss the LVM layer, as I'll be able to create a RAID-0 array, simplifying the administration process.
I'm no expert to say this is better that LVM, but it sounds a promising feature.
If there's any expert on this matter, I'd like to hear your opinions.
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vaxbrat
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PostPosted: Sun Sep 22, 2013 1:56 am    Post subject: I did this wiki entry for it Reply with quote

You can blame me for authorship of this:

https://wiki.gentoo.org/wiki/Btrfs_system_root

I now have three systems set up with a raid 1 flavor of btrfs. The only problems I have seen so far are that btfs is very sensitive to bad memory. If the filesystem gets corrupted, it is hard to salvage in-place with btfs-fsck. At least you can mount the filesystem ro and copy around the corruption to somewhere else and then pull the files back after reformat. Once the one box had more reliable memory installed, I have yet to hear any complaints from it.

The pool concept (subvolumes) are very nice. I have vm's in one subvolume that I set to not auto-defragment, but I have lzo compression enabled there. My /home volumes are set up to autodefrag and compress. I also have repository subvolumes for things like gentoo distfiles and Centos repos which are setup to autodefrag but not bother with compression.

At some point I'm going to take a good long hard look at ceph and will have that running on top of btrfs volumes.
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Ottre
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PostPosted: Tue Sep 24, 2013 6:06 pm    Post subject: Reply with quote

I switched to Btrfs after hearing a really convincing speech by one of the Oracle guys working on it.

Some of his points which I liked:

* By default, Btrfs is optimised for SSD. You don't need to tweak anything.
* Btrfs can recover from any disk failure scenario.
* The Btrfs developers plan to support all of ZFS's features.
* Better suited to generic filesystems than storage (differentiates it from ZFS).
* Btrfs caches free space, a highly requested feature which ZFS doesn't support.
* Efficient backups with a built in send/receive tool.
* Btrfs doesn't require much memory. ZFS is a memory hog.
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Ottre
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PostPosted: Tue Sep 24, 2013 6:08 pm    Post subject: Re: BTRFS features discussion Reply with quote

UX.MAN wrote:

The RAID integrated feature of BTRFS will allow me to dismiss the LVM layer, as I'll be able to create a RAID-0 array, simplifying the administration process.


The developers don't recommend you do this. Btrfs should be used in RAID-1 or RAID-10 mode.
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depontius
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PostPosted: Wed Sep 25, 2013 12:06 pm    Post subject: Reply with quote

I'm getting set to rebuild my NFSV4 server at home. It's currently a relatively small RAID1 using ext4 with an oversized journal. I saw once that NFS releases writes as soon as the journal is written, allowing the rest of the write to finish after the client is released.

I'm planning on the new setup being RAID1 on a pair of 2TB drives. My initial thought would have been to continue with ext4, but I'm seeing more and more that btrfs is looking ready for prime-time. On the latest benchmarks I've seen it's at least not horribly slower than ext4, though perhaps not quite as fast across the board.

Plus I'm looking at the features issues. I've always wanted something like time machine, and had been thinking about how to do it with cron jobs, hard links, etc. But I never got the time to go further on that. It looks like btrfs snapshots would give me that. It also sounds like btrfs will give me RAID1 without using the md stuff, though I'd be interested in hearing more about the pros and cons of both ways.

However I get the impression that there may be issues with serving btrfs over NFS.

Any info/experience?
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Naib
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PostPosted: Thu Sep 26, 2013 11:55 am    Post subject: Reply with quote

what is the state of Btrfs? I have been interested in it but it seems quite fluid still and no complete fsck
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depontius
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PostPosted: Thu Sep 26, 2013 7:28 pm    Post subject: Reply with quote

Naib wrote:
what is the state of Btrfs? I have been interested in it but it seems quite fluid still and no complete fsck


I'd heard a while back that it finally had fsck - I just didn't realize that it's incomplete. I guess that answers my question.
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PostPosted: Tue Oct 08, 2013 10:42 pm    Post subject: btrfs and serving nfs Reply with quote

I'm not having any problems with that. I have four boxes now that are set up for with btrfs raid1 sets on top of raw drives. One of those is used to rsync files off of another box where I have an old fashioned mdadm raid5 array under ext4 that is my primary store. Two of the other three are mythtv servers where /home and the myth stores are on the btrfs. The third is /home and a primary dumping ground for downloads (firewall and torrent box). The fourth will eventually have its mirror set join the others as object stores for ceph when I get one of those circular toits.

Everybody is sharing to everybody else over samba and nfs4. I'm using a nexus 7 with the ES file explorer to consume content over samba. Haven't seen any issues with nfs service or samba from these guys yet, and that includes watching live broadcasts as they are being recorded on the myth servers either inside the myth client or from a remote vlc or smplayer2. I also have been playing too much skyrim lately inside wine, and that whole tree is on top of one of the raid sets. The only ctd's or other problems I have there are from misbehaving mods or after hours of play when the GPU finally whigs out (probably memory fragmentation).
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666threesixes666
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PostPosted: Wed Oct 09, 2013 1:22 am    Post subject: Reply with quote

i have a btrfs virtual machine, only note i had to make is that the /boot has to be a touch larger than my default 100 megs.... more like 256 megs i didn't tinker with raid or any of that. i use JFS on my mission critical systems.
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