Hi Matti.
>>> In theory the EXT2 filesystem max size is 4G * blocksize.
>>> ( 4 * 10^9 * 4 * 10^3 = 16 * 10^12 = 16 TB for 4k blocks. )
>> I understand that on architectures with 8k pages, ext2
>> supports 8k blocksize. If so, you can double that and set
>> the limit at 32 TB on such systems.
> Yes. I was fairly carefull to use generic term "blocksize",
> and then speak of one particular size (4k).
I noticed. This was more a question of whether I had read the
documentation correctly than one of correcting you.
> "man mke2fs" tells us:
> -b block-size
> Specify the size of blocks in bytes. Valid
> block size vales are 1024, 2048 and 4096
> bytes per block. If omitted, mke2fs block
> size is determined by the file system size
> and the expected usage of the filesystem
> (see the -T option).
> So yes, 8k is possible in theory, but utilities don't allow
> it.
That is how I read things as well, so thanks for confirming that
suchlike is the case.
>>> Practicalities begin to hit at various places:
>> One practicality being the scarcity of 32 TB drives, I
>> would presume...
> No problem, have couple of layers of RAID controllers,
> things grow all the sudden...
I wasnae referring to it as a permanent limit so much as one
that is unlikely to be hit today, but isn't all that far away.
> For 32 TB one needs now about thousand disks at the storage
> racks, 500 disks in 4Q2000, latter even less..
My understanding is that disk capacity is going up by about 250%
every six months. Based on that, we would see the following ways
of hitting that limit:
2000 2Q 937 x 35 G
4Q 365 x 90 G
2001 2Q 146 x 225 G
4Q 59 x 560 G
2002 2Q 24 x 1.4 T
4Q 10 x 3.5 T
2003 2Q 4 x 10 T
4Q 2 x 25 T *** > 16 T
2004 2Q 1 x 60 T *** > 32 T
4Q 1 x 150 T *** > 32 T
Of course, this could easily be exceeded, but within 4 years,
the ext2 capacity could easily be a problem...
Best wishes from Riley.
* Copyright (C) 2000, Memory Alpha Systems.
* All rights and wrongs reserved.
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