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users Digest, Vol 38, Issue 13

DISCUSSION Michael Niederle 2 participants 3 messages May 14, 2009 – May 15, 2009 3 messages not in the archive NILFS2 filesystem

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A message that is not in the archive (sent off-list or not yet received): [email protected]

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#2 lore raw

I'm evaluating nilfs as a replacement for the typical layered filesystem approach (unionfs, aufs) used in live-systems.

nilfs performs incredibly well! Its sequential write / random read philosophy is great for accessing pen-drives.

I have only one big problem: I twice corrupted the nilfs-superblock (due to inproper shutdown) leading to a complete data loss each time.

The todo-list mentions that more copies of the superblock are needed. I strongly agree! I think this should be one of the top items on the todo-list.

Greetings, Michael

#3 lore raw

Hi!

Quoted 5 lines · Michael Niederle

I'm evaluating nilfs as a replacement for the typical layered filesystem approach (unionfs, aufs) used in live-systems.

nilfs performs incredibly well! Its sequential write / random read philosophy is great for accessing pen-drives.

Thanks, but I suspect partially the writes are not done on your pendrive ;-)

Quoted 2 lines

I have only one big problem: I twice corrupted the nilfs-superblock (due to inproper shutdown) leading to a complete data loss each time.

Yeah, that is a headache. Milos Jana has been reporting this issue for long periods, but we haven't solved this yet.

What is your pendrive product?

I'd like to buy a pendrive to clarify the root cause of this problem.

BTW, could you try switching IO scheduler to "noop" ? It can be done as follows:

 # cd /sys/block/sda/queue    
   ('sda' should be the device name of the pendrive)
 # cat scheduler
 anticipatory deadline [cfq] noop
 # echo noop > scheduler
 # cat scheduler
 anticipatory deadline cfq [noop]

I think this would help to narrow down the problem.

Quoted 4 lines

The todo-list mentions that more copies of the superblock are needed. I strongly agree! I think this should be one of the top items on the todo-list.

Greetings, Michael

The latest nilfs already has secondary super block in tail of partition. But it looks insufficient for this pendrive problem.

I think ensuring write on unmount should come before that.

Regards,
Ryusuke Konishi

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#5 lore raw
Quoted 10 lines · Ryusuke Konishi
Quoted 4 lines · Michael Niederle

The todo-list mentions that more copies of the superblock are needed. I strongly agree! I think this should be one of the top items on the todo-list.

Greetings, Michael

The latest nilfs already has secondary super block in tail of partition. But it looks insufficient for this pendrive problem.

I think ensuring write on unmount should come before that.

Just a quick note. The write on unmount is already _DONE_ on the source code. I here mean some enhanced operation like diskcache flushing.

Ryusuke Konishi