Difference between revisions of "Talk:Btrfs"

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(Convert Ext3/4 to Btrfs)
(RAID-1 or RAID-5?: see btrfs wiki)
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== Troubleshooting is now outdated ==
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== Comment about stability ==
Would be great of some early adopters would modernize this section now that the stable release of btrfs-progs has hit [testing].  As the warning says, the package now includes the btrfsfsck which can fix problems on the filesystem!
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Btrfs is still under heavy development; it might be useful if someone familiar with btrfs were to add a section commenting on its overall stability. [[User:Vikingurinn|Vikingurinn]] ([[User talk:Vikingurinn|talk]]) 16:52, 17 December 2012 (UTC)
  
[[User:Graysky|Graysky]] 19:27, 28 March 2012 (EDT)
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== RAID-1 or RAID-5? ==
  
== Convert Ext3/4 to Btrfs ==
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"''3 1TB disks in an md based raid1 yields a /dev/md0 with 1TB free space and the ability to safely loose 2 disks without losing data. '''3 1TB disks in a btrfs volume with data=raid1 will allow the storage of approximately 1.5TB of data before reporting full. Only 1 disk can safely be lost without losing data'''.''"
  
Just wondering about step #3: "Setup the network"
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That sounds more like some kind of weird, inefficient RAID-5 arrangement than RAID-1. I don't know btrfs enough to say it's wrong, but I know RAID-1 enough to question it?
I can't see any reason that this is needed. [[User:Capturts|Capturts]] ([[User talk:Capturts|talk]]) 18:35, 23 November 2012 (UTC)
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: It's because of Step #5: Installing btrfs-progs. This is based off of the old install mediums, which  had local versions of programs, unless the remote repositories were enabled like in step #2. Since the new install mediums are remote-only (however they might have some filesystem tools on them), the entire section needs updating. [[User:Klink-a-dink-dink|Klink-a-dink-dink]] ([[User talk:Klink-a-dink-dink|talk]]) 01:06, 24 November 2012 (UTC)
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[[User:Fukawi2|Fukawi2]] ([[User talk:Fukawi2|talk]]) 23:52, 29 April 2013 (UTC)
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:See [https://btrfs.wiki.kernel.org/index.php/FAQ#What_are_the_differences_among_MD-RAID_.2F_device_mapper_.2F_btrfs_raid.3F btrfs wiki]:
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:''btrfs combines all the drives into a storage pool first, and then duplicates the chunks as file data is created. RAID-1 is defined currently as "2 copies of all the data on different disks". This differs from MD-RAID and dmraid, in that those make exactly n copies for n disks. In a btrfs RAID-1 on 3 1TB drives we get 1.5TB of usable data. Because each block is only copied to 2 drives, writing a given block only requires exactly 2 drives spin up, reading requires only 1 drive to spinup.''
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: -- [[User:Karol|Karol]] ([[User talk:Karol|talk]]) 15:59, 17 June 2013 (UTC)
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== btrfs with fsck hook and fstab pass ==
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Apparently one does not need to have a btrfs partition fscked on boot, so there should be a '0' for 'pass' in the fstab for any btrfs partion.
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I had relatively slow boot ups with a pass of '1' (btrfs was root)
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https://bugs.launchpad.net/ubuntu/+source/linux/+bug/791020/comments/27
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the genfstab script puts a '1' in for 'pass' by default

Revision as of 15:59, 17 June 2013

Comment about stability

Btrfs is still under heavy development; it might be useful if someone familiar with btrfs were to add a section commenting on its overall stability. Vikingurinn (talk) 16:52, 17 December 2012 (UTC)

RAID-1 or RAID-5?

"3 1TB disks in an md based raid1 yields a /dev/md0 with 1TB free space and the ability to safely loose 2 disks without losing data. 3 1TB disks in a btrfs volume with data=raid1 will allow the storage of approximately 1.5TB of data before reporting full. Only 1 disk can safely be lost without losing data."

That sounds more like some kind of weird, inefficient RAID-5 arrangement than RAID-1. I don't know btrfs enough to say it's wrong, but I know RAID-1 enough to question it?

Fukawi2 (talk) 23:52, 29 April 2013 (UTC)

See btrfs wiki:
btrfs combines all the drives into a storage pool first, and then duplicates the chunks as file data is created. RAID-1 is defined currently as "2 copies of all the data on different disks". This differs from MD-RAID and dmraid, in that those make exactly n copies for n disks. In a btrfs RAID-1 on 3 1TB drives we get 1.5TB of usable data. Because each block is only copied to 2 drives, writing a given block only requires exactly 2 drives spin up, reading requires only 1 drive to spinup.
-- Karol (talk) 15:59, 17 June 2013 (UTC)

btrfs with fsck hook and fstab pass

Apparently one does not need to have a btrfs partition fscked on boot, so there should be a '0' for 'pass' in the fstab for any btrfs partion. I had relatively slow boot ups with a pass of '1' (btrfs was root)

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/791020/comments/27

the genfstab script puts a '1' in for 'pass' by default