Messages in this thread | | | Date | Sat, 30 Jan 1999 11:01:42 +0100 | From | Harald Koenig <> | Subject | Re: What is max size of ext2fs? |
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the following could be read in linux-kernel not too long ago:
From: "Albert D. Cahalan" <acahalan@cs.uml.edu> To: linux-kernel@vger.rutgers.edu Subject: Re: VFS/ext2fs - large files on the Alpha (fails for 17GB+) Date: Wed, 19 Aug 1998 03:17:07 -0400 (EDT) Message-Id: <199808190717.DAA09901@jupiter.cs.uml.edu>
http://www.cs.uml.edu/~acahalan/linux/ext2.gif
Summary:
1 kB -> 16 GB 2 kB -> 256 GB 4 kB -> 4 TB 8 kB -> 32 TB (limit is block counter)
(8kB is _not_ portabel, it requires 8k pages, so you can't use it on ix86!!)
That assumes you won't hit a 32-bit sector number limit in some other part of the kernel, cutting you off at 1 TB or 2 TB.
From: Matti Aarnio <matti.aarnio@sonera.fi> To: linux-kernel@vger.rutgers.edu Subject: Re: VFS/ext2fs - large files on the Alpha (fails for 17GB+) Date: Thu, 20 Aug 1998 09:17:11 +0300 (EEST) Message-Id: <19980820061717Z92213-453+18@mea.tmt.tele.fi>
> Does that means we *can* have a disk partition (or a RAID system) with a > max. size of 70TB with ext2fs on Intel platforms with a block size of 8192 > bytes? If so, will that be enough to satisfy one's lust for ever expanding > disk space....
Umm... Propably not. While the theorethical block addressability goes up like (blksize/4)**3 function, the maximum offset encodable with blocks is different (non-exponential) function:
32-bits per block offset within FS, giving us 4G blocks maximum. blksize offset (blksize/4)^3 max size 1k 4 TB 16 GB 16 GB 2k 8 TB 256 GB 256 GB 4k 16 TB 4 TB 4 TB 8k 32 TB 64 TB 32 TB So, you can't have 70TB filesystem with EXT2 even if you had the hardware... (counting with 1024 byte kilos that is 64 TB)
Also I think that at Intel you are better off to limit yourself to 4k blocks as those match paging system page size, and using larger blocks than pagesize is rather difficult...
Harald -- All SCSI disks will from now on ___ _____ be required to send an email notice 0--,| /OOOOOOO\ 24 hours prior to complete hardware failure! <_/ / /OOOOOOOOOOO\ \ \/OOOOOOOOOOOOOOO\ \ OOOOOOOOOOOOOOOOO|// Harald Koenig, \/\/\/\/\/\/\/\/\/ Inst.f.Theoret.Astrophysik // / \\ \ koenig@tat.physik.uni-tuebingen.de ^^^^^ ^^^^^
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