Plans for BTRFS in Fedora
sandeen at redhat.com
Wed Feb 23 17:54:58 UTC 2011
On 2/23/11 11:42 AM, Jesse Keating wrote:
> On 2/23/11 5:00 AM, Josef Bacik wrote:
>> This would be a great thing in general since the default ext* image is
>> shrunk down to be installed which creates a bad fs layout which has
>> performance implications.
> Can you expand upon this more? The filesystem is shrunk down when the
> live image is built, but then once it is installed the fs is resized to
> fill out the physical disk / partition it is being installed to.
Shrinking down the filesystem tends to scramble it a bit. All the allocator decisions that were made based on fs size at the time of install go out the window as resize2fs fills in every hole it can find to maximally compress the fs.
I haven't done a real analysis but I would expect that inode::data locality and filesystem fragmentation suffer as a result.
Resizing it back up after the install just attaches free space to the end of the shrunken fs.
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