Shrinking Support
From XFS.org
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(New page: Currently XFS Filesystems can't be shrunk. To suppor shrinking XFS filesystems a few thinks needs to be implemented, based on a list by Dave Chinner [http://marc.info/?l=linux-xfs&m=11913...) |
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Currently XFS Filesystems can't be shrunk. | Currently XFS Filesystems can't be shrunk. | ||
| − | To | + | To support shrinking XFS filesystems a few things needs to be implemented, based on a list by Dave Chinner [https://marc.info/?l=linux-xfs&m=118091640624488&]: |
| + | |||
| + | * A way to check space is available for shrink | ||
* An ioctl or similar interface to prevent new allocations from a given allocation group. | * An ioctl or similar interface to prevent new allocations from a given allocation group. | ||
| Line 8: | Line 10: | ||
* A variant of the xfs_fsr tool to support moving data out of the filesystem areas that go away. | * A variant of the xfs_fsr tool to support moving data out of the filesystem areas that go away. | ||
| − | |||
| − | |||
* Some way to move out orphan metadata out of the AGs truncated off | * Some way to move out orphan metadata out of the AGs truncated off | ||
| Line 15: | Line 15: | ||
* A transaction to shrink the filesystem. | * A transaction to shrink the filesystem. | ||
| − | At that point, we'll | + | At that point, we'll have a "working" shrink that will allow |
| − | shrinking to only 50% of the original size because the log will | + | shrinking to only 50% of the original size because the log |
| − | get in the way. To fix that, we'll need to implement transactions | + | (in the middle of the filesystem) will |
| + | get in the way. To fix that, we'll need to implement transactions | ||
to move the log... | to move the log... | ||
| + | |||
| + | |||
| + | == Available pieces == | ||
| + | |||
| + | * A script from Ruben Porras to check if enough free space is available to support shrinking.[https://marc.info/?l=linux-xfs&m=118581682117599] | ||
| + | |||
| + | * A patch from Ruben Porras to allow / disallow allocation from an allocation group [https://marc.info/?l=linux-xfs&m=118302806818420] plus userspace support for setting / clearing it [https://marc.info/?l=linux-xfs&m=118881137031101] | ||
| + | |||
| + | * The xfs_fsr tool in xfsprogs | ||
| + | |||
| + | * The xfs_reno tool, see [[Unfinished_work#The_xfs_reno_tool]] | ||
| + | |||
| + | * An untested patch from Dave Chinner for a xfs_swap_inodes ioctl that allows to not just defragment extents but moving the whole inode [https://marc.info/?l=linux-xfs&m=119552278931942] and a patch to xfs_reno to use it from Ruben Porras [https://marc.info/?l=linux-xfs&m=119582841808985] | ||
Latest revision as of 21:41, 10 March 2019
Currently XFS Filesystems can't be shrunk.
To support shrinking XFS filesystems a few things needs to be implemented, based on a list by Dave Chinner [1]:
- A way to check space is available for shrink
- An ioctl or similar interface to prevent new allocations from a given allocation group.
- A variant of the xfs_reno tool to support moving inodes out of filesystem areas that go away.
- A variant of the xfs_fsr tool to support moving data out of the filesystem areas that go away.
- Some way to move out orphan metadata out of the AGs truncated off
- A transaction to shrink the filesystem.
At that point, we'll have a "working" shrink that will allow shrinking to only 50% of the original size because the log (in the middle of the filesystem) will get in the way. To fix that, we'll need to implement transactions to move the log...
[edit] Available pieces
- A script from Ruben Porras to check if enough free space is available to support shrinking.[2]
- A patch from Ruben Porras to allow / disallow allocation from an allocation group [3] plus userspace support for setting / clearing it [4]
- The xfs_fsr tool in xfsprogs
- The xfs_reno tool, see Unfinished_work#The_xfs_reno_tool
