USB software RAID questions

cferron · 08-23-2007, 09:33 AM

Hello,

I use slack 12.0 and kernel 2.6.21.5-smp

I have setup a software RAID array setup in one USB external drive (link that follow is not an ad, I want to show the unit.(http://www.startech.com/Product/Item...ESATCASE2&c=CA). Each drive inside are 500Gb. I have successfully created the Raid1 array (md0) with mdadm
command issued:

Code:

mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1

cat /proc/mdstat

Code:

Personalities : [linear] [raid1]
md0 : active raid1 sdc1[1] sdb1[0]
      488383936 blocks [2/2] [UU]

unused devices: <none>

The things I would like to know, understand:
1) md0 was created, now do I have to partion it, format it? Any suggestion?

2) Next time I boot will the system recognize the RAID? If so how? there is no config file....

3) What if the USB drives are connected in a different order and they get assigned a different sd"x" name as a device name!

4) Can I create a udev rule that will mount the RAID on the KDE desktop or a least in a directory I specify. What would be the unique thing I could recognize with udev? the md0 UUID?

5) I don't know if my drives (that compose the array) are DMA enabled... Can I check this (hdparm does not seem to work for the array, neither for it's devices) should I have done this before? Do I have to kill/stop my array md0 and start again.

Thanks for your help!

Claude

mdadm -D /dev/md0

Code:

/dev/md0:
        Version : 00.90.03
  Creation Time : Thu Aug 23 20:07:24 2007
     Raid Level : raid1
     Array Size : 488383936 (465.76 GiB 500.11 GB)
  Used Dev Size : 488383936 (465.76 GiB 500.11 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Fri Aug 24 10:06:18 2007
          State : active
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           UUID : 44d19ca8:f36399f6:69aaf21d:159647a1
         Events : 0.7

    Number   Major   Minor   RaidDevice State
       0       8       17        0      active sync   /dev/sdb1
       1       8       33        1      active sync   /dev/sdc1

mRgOBLIN · 08-24-2007, 04:35 AM

Quote:

Originally Posted by cferron

Hello,

The things I would like to know, understand:
1) md0 was created, now do I have to partion it, format it? Any suggestion?

2) Next time I boot will the system recognize the RAID? If so how? there is no config file....

3) What if the USB drives are connected in a different order and they get assigned a different sd"x" name as a device name!

4) Can I create a udev rule that will mount the RAID on the KDE desktop or a least in a directory I specify. What would be the unique thing I could recognize with udev? the md0 UUID?

5) I don't know if my drives (that compose the array) are DMA enabled... Can I check this (hdparm does not seem to work for the array, neither for it's devices) should I have done this before? Do I have to kill/stop my array md0 and start again.

Really you should have a good read of this first.

http://www.userlocal.com/articles/ra...ackware-12.php

1) You need to format it.

2) Yes there is an /etc/mdadm.conf file

3) You should have set the drive partitions as type FD so they get auto-detected, the UUIDs will be in /etc/mdadm.conf after you add them.

4) Use /etc/fstab to mount the device /dev/md0 /where/ever/you/want

5) Well you are using the "Mass Storage" so I'm not sure if DMA has any effect there... maybe someone else has an answer for that.

Gobby

cferron · 08-25-2007, 11:50 AM

Quote:

Originally Posted by mRgOBLIN

1) You need to format it.

Well, here is what I did:
/dev/sdb1 (FD Linux RAID)
/dev/sdc1 (FD Linux RAID)
/dev/md0 Formatted as EXT3

Quote:

Originally Posted by mRgOBLIN

2) Yes there is an /etc/mdadm.conf file

I was aware of that, but this config file says it was supposed to generate by itself and it did not.
DEVICE /dev/sdb1 /dev/sdc1
ARRAY /dev/md0 UUID=d83f99fa:c5eadb32:ca5f9faa:98d12bf
MAILADDR an_mail@gmail.com
PROGRAM /usr/sbin/handle-mdadm-events

As for the PROGRAM line, I'm not sure what to put there?

Quote:

Originally Posted by mRgOBLIN

3) You should have set the drive partitions as type FD so they get auto-detected, the UUIDs will be in /etc/mdadm.conf after you add them.

Ok, but still I have USB drive that might not alwasy get mounted as sdb and sdc depending of the order I connect the drives... Sould I do a udev rules that will create /dev/raid_devices_1 & /dev/raid_devices_2 ??? Not sure where to start with this... Any suggestions?

Quote:

Originally Posted by mRgOBLIN

4) Use /etc/fstab to mount the device /dev/md0 /where/ever/you/want

This is the line I added
/dev/md0 /mnt/raid ext3 auto,nouser,exec,rw 2 0

I this point I still wonder how md0 gets active espacially if the sdb1 and sdc1 are not present for a reason...???

yoron · 08-26-2007, 03:07 PM

If you want to use them as raid you will have to leave them as they are mounted, once and for all. Otherwise i belive in the idea. Try it :) And tell us if it worked ::))
They won't die, (i think :)