Raid in Linux Redhat 8.0

[castro_2]

I have a 2 disks the 34 GB, raid 1 for software.
How can I khonw if the disks are synchronous?

If one disk broken, How is the procedure to change it?.
Thanks

[Steven E. Protter]

If you have used the disk druid to set it up or the raid tools after installation, raid 1 will fail over without even notifying you.

During a maintenance window, you should shut down the server, unplug the power to the primary boot disk and then boot the server.

If the drive is a hot swap, you can do it while its up. Just make sure the whole server is backed up before you start.

This technology is not as mature as it is in the proprietary unixes like hp-ux

SEP

[Huc_1]

How about lsraid

man lsraid
ex:
# lsraid -A -d /dev/sda1

I dont have a system with raid to check it on underhand.

Tell us how that fares.

J-P

[Dave Falloon]

I have had better luck setting up and monitoring raid using evms here is a link to a tutorial:

http://www-106.ibm.com/developerworks/linux/library/l-fs12/?t=gr,lnxw16=AFIG12

the evms gui is really easy to use, although initially setting up a machine to use evms or lvm ( sistina linux, download at: http://www.sistina.com/products_lvm_download.htm) can be daunting.

If you are using software raid tools, you should be able to check out your raid array status in /proc/mdstat. Did you set the raid array up during the install process or by hand afterwards with mkraid?

Dave

[castro_2]

I used disk druid.

lsraid -A -a /dev/md0
[dev 9, 1] /dev/md0
[dev 8, 1] /dev/sda1
[dev 8, 17] /dev/sdb1

lsraid -A -a /dev/md1
[dev 9, 1] /dev/md1
[dev ?, ?] (unknown)
[dev 8, 22] /dev/sdb6

How can I do to synchronous manualy?

[Steven E. Protter]

Casro,

greetings. The synch command will synch all disk information and force the mirrors to update.

Look at this doc:
http://www.spinics.net/lists/raid/msg03088.html

Linux raid commands:
http://www.linuxgazette.com/issue17/raid.html

A good article RH 8 specific.
http://www.linuxjournal.com/article.php?sid=6412

SEP
Works for points or money.

[castro_2]

The command synch I don´t found.
Than

[Dave Falloon]

What is the output from this command:

cat /proc/mdstat

Have you started the raid array with the raidstart command?

Dave

[Dave Falloon]

SEP, do you mean the sync command?

That flushes the cache on the disks does it also force raid 1 devices to sync up?

Dave

[castro_2]

I change the disk broken, but when turn-on the system don´t work.
It don't found the grub

[Dave Falloon]

Ok now I'm a little lost, bear with me:

First Scenario:

You had a mirror and then a disk went, which broke the mirror, and you replaced the bad disk and are now asking how do you recreate your mirror?

Second Scenario:

You have never had a mirror setup in the first place but in the course of setting up the first mirror you realized that a disk was broken and you have replaced it and want to continue setting up the mirror for the first time but can not boot?

Which is closer to whats going on?

Dave

[Dave Falloon]

After rereading the post I think you are closer to the first scenario I described.

have you run the command to add the blank disk into the raid array?

raidhotadd /dev/mdX /dev/sdX

[castro_2]

First Scenario
I have two disks in Raid 1 with disk Druid.
The first disk is broken, and change for another new disk. Then the system don´t start becasuse don't found the grub. The system don't find SO.

I can´t do raidhotadd /dev/mdX /dev/sdX because when I change the disk the system don´t boot.

[Dave Falloon]

Here is a link to the software RAID howto:

http://www.tldp.org/HOWTO/Software-RAID-HOWTO-4.html#ss4.7

read the section 4.14, the relevant information is the description of how to boot off the rescue red hat rescue disk, recreate the raid devices, and finally rebuild your raid array, watching the progress in /proc/mdstat

I hope that helps,

Dave

[Dave Falloon]

Castro did it work?

Do you need more assistance?

Dave