Messages in this thread | | | Date | Sun, 13 Jul 2008 14:06:02 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH 3/3] Add timeout feature |
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Hi!
> NEED - provide way for SAN and hardware raid storage to do > its snapshot/copy function while the system was in-use and > get an image that could mount cleanly. Without freeze, at > a minimum we usually needed filesystem metadata recovery > to run, worst case is completely unusable snapshits :) > > freezefs() is single-level: > > ENOTSUPPOTED - by any other fs > EOK - done > EINPROGRESS > EALREADY > > As implemented, freezefs only ensures the metadata is > consistent so the filesystem copy can mount anywhere. > > This means ONLY SOME metadata (or no metadata) is flushed and > then all metadata updates are stopped. User/kernel writes > to already allocated file pages WILL go to a frozen disk.
That's the difference here. They do write file data, and thus avoid mmap()-writes problem.
...and they _still_ provide auto-thaw. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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