Success with RAID1 on Alpha
I'd like to report success with software RAID1 on my PC164LX. I know
some people were reporting failure with software raid on Alpha some
months ago.
I used stock kernel: 2.4.22-rc2 with a patch from
<http://www.spinics.net/lists/raid/msg02526.html>. This patch is
absolutely required, or any I/O to the built raidset caused a kernel
oops.
I build raid1 and md as modules, which means I am unable to RAID my /
partition without hacking init scripts to do a chroot on boot (or using
an initrd, which I consider too much trouble). I'm also not sure
autorecognition would work anyway, since I don't know how to mark a BSD
disklabel partition as part of a RAID (in DOS partition format, you use
partition type 'fd' but BSD disklabel partition types seem to only go
up to 0x10). I'm also lucky that LX can boot off of its builtin IDE
controller, or I'd still need SCSI (or floppy :-) ).
All other filesystems are now off of two identical 120GB Maxtor IDE
drives. Getting rid of the old, small, power-hungry SCSI drives (and
controller) has made my UPS much happier :-)
In order to boot aboot/SRM off of an IDE drive, I had to either
manually specifiy 'boot dqa0.0' or remove the second (slave) drive from
the primary IDE controller. With the second drive present, 'b dqa0'
would give "Failed to send Read to dqa0' error messages. This means
that auto_action boot did not work. I'm not sure if this is specific
to my setup or not.
I also configured the root filesystem with 'mke2fs -j -O none' (i.e.
kernel 2.2-compatible ext2) for aboot's sake, though I don't know if
this was strictly necessary.
For the non-Alpha-specific parts, I followed the Software RAID HOWTO at
<http://www.tldp.org/HOWTO/Software-RAID-HOWTO.html>
jekyl:~$ df -h
/dev/hda2 1.9G 173M 1.6G 10% /
/dev/md2 9.2G 2.1G 6.7G 25% /usr
/dev/md1 2.8G 754M 1.9G 29% /var
/dev/md3 33G 8.1G 23G 27% /home
/dev/md4 33G 2.6G 29G 9% /backup
/dev/md5 33G 33M 31G 1% /scratch
jekyl:~$ cat /proc/mdstat
Personalities : [raid1] read_ahead 1024 sectors
md5 : active raid1 hdc7[1] hda7[0]
34811200 blocks [2/2] [UU]
md4 : active raid1 hdc6[1] hda6[0]
34810688 blocks [2/2] [UU]
md3 : active raid1 hdc5[1] hda5[0]
34811200 blocks [2/2] [UU]
md2 : active raid1 hdc4[1] hda4[0]
9765888 blocks [2/2] [UU]
md1 : active raid1 hdc3[1] hda3[0]
2930176 blocks [2/2] [UU]
unused devices: <none>
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