Linked by John Finigan on Mon 21st Apr 2008 19:00 UTC
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RE[3]: Background articles
by jwwf on Tue 22nd Apr 2008 16:46
in reply to "RE[2]: Background articles"
"ZFS is not a pure-play log structured FS and requires no cleaner.
That's an interesting statement. Can you tell me where I can more information about the fact that ZFS doesn't require a cleaner ? "
Check this out:
http://blogs.sun.com/nico/entry/comparing_zfs_to_the_41
By saying that it doesn't require a cleaner, what I had in mind is that it isn't background garbage collected and does not treat the disk as a circular log of segments that are either clean or dirty. It is more like a versioned tree of blocks. By cleaner I mean an asynchronous daemon that eventually "gets around to" cleaning segments that are dirty.
However, I am always willing to learn something. Do you think this evaluation is incorrect?
RE[4]: Background articles
by Abacus_ on Tue 22nd Apr 2008 18:51
in reply to "RE[3]: Background articles"
"[q]ZFS is not a pure-play log structured FS and requires no cleaner.
That's an interesting statement. Can you tell me where I can more information about the fact that ZFS doesn't require a cleaner ? "
Check this out:
http://blogs.sun.com/nico/entry/comparing_zfs_to_the_41
By saying that it doesn't require a cleaner, what I had in mind is that it isn't background garbage collected and does not treat the disk as a circular log of segments that are either clean or dirty. It is more like a versioned tree of blocks. By cleaner I mean an asynchronous daemon that eventually "gets around to" cleaning segments that are dirty.
However, I am always willing to learn something. Do you think this evaluation is incorrect? [/q]
As known, filesystems like ZFS and the Sprite LFS write data to a huge log. This log contains both data and metadata. I'm not a ZFS expert, but how can ZFS discover unreferenced blocks without rereading the metadata that was written earlier to the log (assuming that not all metadata fits in RAM) ?





Member since:
2006-12-08
That's an interesting statement. Can you tell me where I can more information about the fact that ZFS doesn't require a cleaner ?