Messages in this thread | | | From | Andreas Dilger <> | Date | Fri, 10 May 2002 17:46:23 -0600 | Subject | Re: [PATCH] remove 2TB block device limit |
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On May 11, 2002 05:12 +1000, Peter Chubb wrote: > 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))
Any chance you could rename this from "LFS" to something else (e.g. LBD for Large Block Device). LFS == Large File Summit which describes the use/access of > 2GB _files_ on 32-bit systems under Unix.
> 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)
For 64-bit systems like Alpha, it is relatively easy to use 8kB blocks for ext3. It has been discouraged because such a filesystem is non-portable to other (smaller page-sized) filesystems. Maybe this rationale should be re-examined - I could probably whip up a configure option for e2fsprogs to allow 8kB blocks in a few hours.
Does x86-64 and/or ia64 actually _use_ > 4kB page sizes? If so, it may be more worthwhile to allow larger block sizes with e2fsprogs. It may be that the kernel supports >4kB blocks already on systems with larger PAGE_SIZE, I don't know (no way for me to test this).
> 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.
I find it somewhat ironic that you suggest reiserfs over ext3, when in fact they both currently have the same 16TB filesystem limit. On your web page, you say the ext[23] limit is 1TB, which it definitely is not (unless there are bugs in the code). There is currently a 16TB filesystem limit for 4kB blocks, but there are plans towards fixing that also.
> --- 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.
LVM does not need to have partitions, and presumably EVMS using Linux or AIX LVM devices doesn't either.
Cheers, Andreas -- Andreas Dilger http://www-mddsp.enel.ucalgary.ca/People/adilger/ http://sourceforge.net/projects/ext2resize/
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