"Theodore Y. Ts'o" wrote:
>
> Date: Mon, 10 Jan 2000 10:24:21 +0000 (GMT)
> From: Tigran Aivazian <[EMAIL PROTECTED]>
>
> So, it would seem to me that you either did not answer Manfred's question
> about what happens if one transfers a large (>2T) ext2 filesystem (with no
> large >2G files ever created in it) to i386 or you answered it in a way I
> did not understand.
>
> The ext2 filesystem uses 32 bit unsigned block pointers regardless of
> whether it's on a 32-bit system or a 64-bit system. Hence, the question
> doesn't make any sense (which is why I assumed you were talking about
> file sizes and not overall filesystem size). It will work just fine,
> because nothing is changing.
Ok. Let me explain it again:
Someone bought you four 1 Terrabyte SCSI drives. You join them into one
4 Terrabyte software-RAID0 set.
You attach that set to an Linux Alpha computer.
The RAID tools _could_ allow you to format the disks as one huge ext2
disk. The on-disk format of ext2 supports a 4 TB volume.
You use these disks for a few weeks, then your Alpha breaks down. You
decide to attach these disks to your x86 computer.
Now the RAID tools MUST NOT mount the 4 TB disk array, or you'll destroy
your data.
[the calculation
bh[i]->b_rsector = bh[i]->b_blocknr*(bh[i]->b_size>>9);
in ll_rw_blk.c would overflow]
I've already checked LVM, and the LVM utilities contain a safety check:
they do not allow you to create a volume > 1 terrabyte. I've not yet
checked if the raid tools contain such checks.
As a second safety net, I would add an additional check to the ext2
mount routines [ie do not mount disks > 2 TB on 32-bit platforms,
perhaps with a mount parameter to override it. We could remove it if we
know that it's safe]
--
Manfred
