Messages in this thread | | | Date | Tue, 29 Oct 2002 23:03:20 -0500 | From | Jeff Garzik <> | Subject | Re: ANNOUNCEMENT: Squashfs released (a highly compressed filesystem) |
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Phillip Lougher wrote:
> Samuel Flory wrote: > >> Phillip Lougher wrote: >> >>> Hi, >>> >>> First release of squashfs. Squashfs is a highly compressed >>> read-only filesystem for Linux (kernel 2.4.x). It uses zlib >>> compression to compress both files, inodes and directories. Inodes >>> in the system are very small and all blocks are packed to minimise >>> data overhead. Block sizes greater than 4K are supported up to a >>> maximum of 32K. >>> >>> Squashfs is intended for general read-only filesystem use, for >>> archival use, and in embedded systems where low overhead is needed. >>> >>> Squashfs is available from http://squashfs.sourceforge.net. >>> >>> The patch file is currently against 2.4.19. There is further info >>> on the filesystem design etc. in the README. >>> >>> I'l be interested in getting any feedback, advice etc. on it. >>> >> >> What are the advantages of squashfs vs cramfs? >> >> >> > > Cramfs was the inspiration for squashfs. Squashfs basically gives > better compression, bigger files/filesystem support, and more inode > information. > > 1. Blocks upto 32K are supported - data is compressed in units of 32K > which achieves better compression ratios than compressing in 4K > blocks. Generally using bigger than 4K blocks are a bad idea, because > the VFS calls the filesystem in 4K pages. Squashfs explictly pushes > the extra block data into the page cache.
I'm curious if you looked at ntfs-tng's code before implementing this. It's pretty darned optimal...
> 2. Squashfs compresses inode and directory information in addition to > file data. Inodes/directories generally compress down to 50%, or say > on average 8 bytes or less per inode.
squashfs or mksquashfs?
A r/w compressed filesystem would be darned useful too :)
Jeff
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