Re: partion code doesn't consider 2048 bytes sectors

Paul Slootman (paul@wau.mis.ah.nl)
Mon, 15 Sep 1997 15:12:04 GMT


-=Magick=- <owner-linux-kernel@vger.rutgers.edu> wrote:
>
>I have a scsi MO-drive, and it uses a hardware sectorsize
>of 2048 bytes. The partitions I make on a disk under dos/windoze
>have a sectorsize of 2048 bytes. But under linux the partition
>code assumes a sectorsize of 512 bytes.

Are you sure the problem is in the partition code?

I recently tried a SCSI disk formatted to 1K sectors. It looked
like it worked (fdisk seemed to be OK), but accessing partitions
after this failed with all sorts of horrifying errors. Before
you say, "Aha, partitions!", when I replaced the NCR810 SCSI
controller with an Adaptec 1542CF, it worked perfectly. I think
it also works with my Buslogic card.

So, I think there is some problem with the NCR810 code.
You don't mention what SCSI adapter you're using?

BTW: it looks like disks with 1K sectors are *slower* than disks
with 512 byte sectors; here is a sample bonnie output:

-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
512 bytes 58 928 21.9 1025 6.1 384 5.1 751 17.4 1150 6.0 47.4 1.9
1024 bytes 58 837 21.2 984 5.8 418 5.3 764 17.5 1150 5.9 48.3 1.8

This is not what I had expected. The filesystem on each is identical,
and located on the same place physically on the disk (at the end).

The throughput is about half of what is attained with the NCR810
(the 512 byte numbers; it simply doesn't work with 1024 byte sectors).

Paul Slootman

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