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NILFS: A File System to Make SSDs Scream (Linux Mag)
Linux Magazine has a look at the Nilfs2 filesystem which is part of 2.6.30. "One of the most noticeable features of NILFS is that it can 'continuously and automatically save instantaneous states of the file system without interrupting service'. NILFS refers to these as checkpoints. In contrast, other file systems such as ZFS, can provide snapshots but they have to suspend operation to perform the snapshot operation. NILFS doesnt have to do this. The snapshots (checkpoints) are part of the file system design itself."
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NILFS: A File System to Make SSDs Scream (Linux Mag) Posted Jun 4, 2009 20:07 UTC (Thu) by vaurora (subscriber, #38407) [Link]
The comment about ZFS snapshots requiring suspension of file system operations is wrong. ZFS snapshots are nearly instantaneous and built-in to the file system design.
NILFS: A File System to Make SSDs Scream (Linux Mag) Posted Jun 4, 2009 20:24 UTC (Thu) by asdlfiui788b (guest, #58839) [Link]
"Nearly". ZFS Fail. And it's patent encumbered and anti-free as well too boot!
NILFS: A File System to Make SSDs Scream (Linux Mag) Posted Jun 4, 2009 21:03 UTC (Thu) by nix (subscriber, #2304) [Link]
Making ZFS snapshots is 'nearly' free because of course it has to write
something to the disk to persist the snapshot, and of course that doesn't take zero time. The window during which other operations are suspended is exactly as wide as the window during which they are suspended by, say, a write() (or, more accurately, a rename()). That's not exactly enormous, certainly not compared to the huge gaping window incurred by an LVM snapshot creation.
(Also, er, you *do* know that Val was a ZFS hacker, right? So you're
ZFS patently unfree Posted Jun 7, 2009 0:35 UTC (Sun) by man_ls (subscriber, #15091) [Link] The bit about patents seems to be unfortunately true, though. And it is not the fault of Val or other employees either.
NILFS: A File System to Make SSDs Scream (Linux Mag) Posted Jun 11, 2009 9:08 UTC (Thu) by engla (guest, #47454) [Link]
It's probably the same with NILFS2 (the sentence in the article was just a try at quick points); NILFS2 creates checkpoints as part of normal operations, but to mark a checkpoint as snapshot (to preserve after GC), you have to make a small write to disk. So not much difference between ZFS and NILFS2 there.
NILFS: A File System to Make SSDs Scream (Linux Mag) Posted Jun 4, 2009 21:07 UTC (Thu) by jlmassir (guest, #48904) [Link]
Why is it listed under "Miscellaneous filesystems"? Isn't it supposed to be a general purpose filesystem like ext3 or btrfs?
NILFS: A File System to Make SSDs Scream (Linux Mag) Posted Jun 5, 2009 0:03 UTC (Fri) by ZhuYanhai (subscriber, #44977) [Link]
Maybe because it's total different type?Nilfs is a log structured file system.
NILFS: A File System to Make SSDs Scream (Linux Mag) Posted Jun 6, 2009 4:31 UTC (Sat) by jlmassir (guest, #48904) [Link]
It may be only my impresion, but "Miscellaneous filesystems" seems to contain filesystems less important to a linux system, irrespective of their internal structure:
Miscellaneous filesystems
I just don't understand puting a promising filesystem like nilfs2 alongside with filesystems that will never be used in linux, like qnx4.
NILFS: A File System to Make SSDs Scream (Linux Mag) Posted Jun 16, 2009 8:57 UTC (Tue) by forthy (guest, #1525) [Link] What does the type matter? This is an implementation detail. What matters is: Is it fast? Is it safe (crash-proof)? Does it have useful additional features (like undelete and snapshots)? Does it cause wear on flash file systems or prevent wear? Does it degenerate through time (fragmentation)? IMHO, log structured file systems have better answers to these questions than traditional file systems. Implementation quality matters - e.g. how good the garbage collection really is. Generally speaking, a garbage collection system could improve the performance of a file system over time, especially the read performance in typical situations on a rotating disk by placing files together that are accessed together (readahead).
NILFS: A File System to Make SSDs Scream (Linux Mag) Posted Jun 5, 2009 10:43 UTC (Fri) by rodgerd (guest, #58896) [Link]
Seeing it as a special-purpose SSD filesystem seems a little narrow to me. On the whole I like it better than btrfs, to be honest.
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