On 05/30/2014 06:00 PM, Martin wrote:
OK... I'll jump in...
On 30/05/14 21:43, Josef Bacik wrote:
Hello,
TL;DR: I want to only do snapshot-aware defrag on inodes in snapshots
that haven't changed since the snapshot was taken. Yay or nay (with a
reason why for nay)
[...]
=== Summary and what I need ===
Option 1: Only relink inodes that haven't changed since the snapshot was
taken.
Pros:
-Faster
-Simpler
-Less duplicated code, uses existing functions for tricky operations so
less likely to introduce weird bugs.
Cons:
-Could possibly lost some of the snapshot-awareness of the defrag. If
you just touch a file we would not do the relinking and you'd end up
with twice the space usage.
[...]
Obvious way to go for fast KISS.
One question:
Will option one mean that we always need to mount with noatime or
read-only to allow snapshot defragging to do anything?
Yeah atime would screw this up, I hadn't thought of that. With that
being the case I think the only option is to keep the old behavior, we
don't want to screw up stuff like this just because users used a backup
program on their snapshot and didn't use noatime. Thanks,
Josef
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