Re: Alpha Raid Tools

[axp amazing ch]

On Nov 16 Jacek Perry (chrobry@yahoo.com) wrote:

> Now my question is how do I compile the raid tool, and do I have to
> get specific ones for alpha (I am running LX164)?

About a month ago I wrote to this list (does the listarchive
at Redhat work now?):

Hi

Yesterday I added one more disk to my Alpha and
I used the opportunity to create some raid-arrays.

As I had some troubles to get it working, I thought,
I'd share my findings with you:


I got "raidtools-0_51beta9" and "raid0145-19980913-2_0_35"
from ftp.kernel.org/pub/linux/kernel/deamons (or
something very similar).

I have RH5.1, Kernel 2.0.35 from RH (without any
patches), egcs1.1a on a PC164.


The Raid-patches for the Kernel applied cleanly
(beside one patch to asm-i386/irq.h (I think)).


To compile the Tools I needed to make the
following changes:

In "/usr/src/linux/include/asm-alpha/bitops.h" I added
--------------------------------------------------
extern inline int ffs(int word)
{
	int result = ffz(~word);
	return word ? result+1 : 0;
}
--------------------------------------------------
right after the definition of ffz (took that one from
a 2.1.xxx Kernel)


"/usr/src/linux/include/linux/raid/md.h" was missing
a "#include <asm/segment.h>".

I think, that was all I changed.



As the doc is a bit unclear (no comment), here a
short rundown on hot to use it:

1. make a new kernel with:
--------------------------------------------------
 CONFIG_BLK_DEV_MD=y
 CONFIG_AUTODETECT_RAID=y
 CONFIG_MD_LINEAR=y
 CONFIG_MD_STRIPED=y
 CONFIG_MD_MIRRORING=y
 CONFIG_MD_RAID5=y
--------------------------------------------------
(you don't need all raid-levels if you don't want
to...)


2. compile and install the tools:
"cd raidtools;./configure;make;make install"


3. create "/etc/raidtab". mine looks like this:
--------------------------------------------------
raiddev /dev/md0
    raid-level                0
    nr-raid-disks             3
    nr-spare-disks            0
    chunk-size                16
    persistent-superblock     1

    device                    /dev/sdc2
    raid-disk                 0
    device                    /dev/sde2
    raid-disk                 1
    device                    /dev/sdf2
    raid-disk                 2

raiddev /dev/md1
    raid-level                0
    nr-raid-disks             2
    nr-spare-disks            0
    chunk-size                16
    persistent-superblock     1

    device                    /dev/sdd1
    raid-disk                 0
    device                    /dev/sdf1
    raid-disk                 1
--------------------------------------------------
(The persistent-superblock isn't documented anywhere,
but it's needed for normal operation. also the
chunk-size entry is mandatory).


4. use "fdisk" to set the partitiontype to "86" for all
the future raid-partitions (needed for autodetection
on the next reboot (you can even put the root on a
raid-partition, but of course you need to keep the
kernel on a non-raid-partition).


5. "mkraid -a"


6. "mke2fs /dev/md0" and "mke2fs /dev/md1"


7. make entries in your "/etc/fstab".


8. mount them and use them :)


Hope I didn't forget anything. It works for me (so
far). No warranty....


Bye
 dworz