Messages in this thread | | | Date | Sat, 11 May 2002 19:13:39 +0100 | From | Padraig Brady <> | Subject | Re: [PATCH] remove 2TB block device limit |
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I found the following related graph from Mr. Cahalan very informative: http://www.cs.uml.edu/~acahalan/linux/ext2.gif I just might get around to updating/expanding it.
Padraig.
Peter Chubb wrote: >>>>>>"Jeremy" == Jeremy Andrews <jeremy@kerneltrap.org> writes: >>>>> > > Jeremy> Peter, Out of curiousity, what then does the new filesystem > Jeremy> limit become, on a 64-bit system? Will all filesystems > Jeremy> support your changes? > > This depends on the file system. > See > http://www.gelato.unsw.edu.au/~peterc/lfs.html > (which I'm intending to update next week, after some testing to > check the new limits with my new code -- I found the 1TB limit in > the generic code (someone using a signed int instead of unsigned long)) > > There are three different limits that apply: > > --- The physical layout on disc (e.g., ext2 uses 32-bit for block > numbers within a file system; thus the max size is > (2^32-1)*block_size; although it's theoretically possible to use > larger blocksizes, the current toolchain has a maximum of 4k, > thus the largest size of an ext[23] filesystem is ((2^32)-1)*4k > bytes --- around 16TB) > > It's extremely unlikely that you'd want to use a non-journalled > file system on such a large partition, so your best bets are > reiserfs, jfs or XFS. jfs and xfs work well on enormous > partitions on other platforms; the current version of reiserfs is > somewhat limited, but version 4 will allow larger file systems. > > > --- Limitations imposed by the partitioning scheme. > As far as I know, only the EFI GUID partitioning scheme uses > 64-bit block offsets, so under any other scheme you're limited to > 2^32 or 2^31 blocks per disc; some use the underlying hardware > sector size, some use a block size that's multiple of this. > > --- The page cache limit (which on a 32-bit system is 16TB; on a 64 > bit system is 18 EB > > > Jeremy> Mind if I quote what you say on my webpage? > > Go ahead > > -- > Peter Chubb > peterc@gelato.unsw.edu.au http://www.gelato.unsw.edu.au > -
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