Messages in this thread | | | Date | Thu, 26 Apr 2007 11:44:51 -0500 | From | Amit Gud <> | Subject | Re: [RFC][PATCH] ChunkFS: fs fission for faster fsck |
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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 ?
Hello Alan,
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 continuation inodes.
AG -- May the source be with you. http://www.cis.ksu.edu/~gud
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