Re: [RFC][PATCH] ChunkFS: fs fission for faster fsck
From: Amit Gud
Date: Thu Apr 26 2007 - 12:46:43 EST
Alan Cox wrote:
Preventive measures are taken to limit only one continuation inode per
file per chunk. This can be done easily in the chunk allocation
algorithm for disk space. Although I'm not quite sure what you mean by
How are you handling the allocation in this situation, are you assuming
that a chunk is "out of bounds" because part of a file already lives on
it or simply keeping a single inode per chunk which has multiple sparse
pieces of the file on it ?
ie if I write 0-8MB to chunk A and then 8-16 to chunk B can I write
16-24MB to chunk A producing a single inode of 0-8 16-24, or does it have
to find another chunk to use ?
You re-use the same inode with multiple sparse pieces.
This way you avoid hopping around continuation inodes and coming back to
same chunk with which you started but this time on a different
continuation inode. This may not be I/O intensive for successive
traversals if the continuation inodes are pinned in the memory, but it
certainly is a waste of resource - inodes. Not allowing this would make
worst case of every file having a continuation inode in every chunk,
even worse; may be like only single file exist in the file system and
rest all inodes in all chunks (including file's own chunk) are
May the source be with you.
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