RAID5 problems

2 messages, 2 authors, 2002-08-19 · open the first message on its own page

RAID5 problems

From: Rick Altherr <hidden>
Date: 2002-08-19 16:39:27

I am brand new to software RAID on linux so please bear with me.

I have (4) 23GB SCSI drives on an Adaptec 2940UW controller in an
alphastation 600.  I created BSD disklabels on all the drives and
partitioned them as one partition per drive.  I made a raidtab containing
all 4 partitions as members of a single RAID5 array.  I ran mkraid
/dev/md0 and the raid array was created and functioned.

This is where the problem lies.  If I stop the RAID array using raidstop
/dev/md0 and run fdisk on each drive, it reports that each drive has a BSD
disklabel with a single partition.  However, if I format the RAID array
using mke2fs -b 4096 -R stride=8, stop the array with raidstop, and check
each drive with fdisk, the disklabel is removed on the second and third
drives only.  The first and fourth are fine though.

Trying to start the array again with raidstart fails and mkraid will not
recreate the array until I create disklabels on the second and third
drives.

I have not tried any other filesystems as ext2 is the only one my kernel
currently supports.

Any ideas?
-- 
Rick Altherr
KC8APF
kc8apf@kc8apf.net



RE: RAID5 problems

From: Cal Webster <hidden>
Date: 2002-08-19 21:45:26

Sounds like your label is being overwritten. Be sure that you do not use
cylinder 0 in your partition. Start it on cyl 1.

Here is an excerpt from the "fdisk" man page on our Sparc running Aurora
Linux:


       A BSD/SUN type disklabel can describe  8  partitions,  the
       third of which should be a `whole disk' partition.  Do not
       start a partition that  actually  uses  its  first  sector
       (like  a  swap  partition)  at cylinder 0, since that will
       destroy the disklabel.

--Cal Webster
-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org]On Behalf Of Rick Altherr
Sent: Monday, August 19, 2002 10:39 AM
To: linux-raid@vger.kernel.org
Subject: RAID5 problems


I am brand new to software RAID on linux so please bear with me.

I have (4) 23GB SCSI drives on an Adaptec 2940UW controller in an
alphastation 600.  I created BSD disklabels on all the drives and
partitioned them as one partition per drive.  I made a raidtab containing
all 4 partitions as members of a single RAID5 array.  I ran mkraid
/dev/md0 and the raid array was created and functioned.

This is where the problem lies.  If I stop the RAID array using raidstop
/dev/md0 and run fdisk on each drive, it reports that each drive has a BSD
disklabel with a single partition.  However, if I format the RAID array
using mke2fs -b 4096 -R stride=8, stop the array with raidstop, and check
each drive with fdisk, the disklabel is removed on the second and third
drives only.  The first and fourth are fine though.

Trying to start the array again with raidstart fails and mkraid will not
recreate the array until I create disklabels on the second and third
drives.

I have not tried any other filesystems as ext2 is the only one my kernel
currently supports.

Any ideas?
--
Rick Altherr
KC8APF
kc8apf@kc8apf.net




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