Mark
asked on
Linux RAID Setup
I've found some rather nifty instructions on setting up softRAID on linux (https://raid.wiki.kernel.org/index.php/RAID_setup). But I can't discern whether the boot device is/can/or should be part of the raid. I presume I will download, install and configure mdadm while running a normal /dev/sdx device. Should the boot device be a physically separate drive? Can the RAID be set up on top of and incorporate the boot device? Has anyone done this?
SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
ASKER CERTIFIED SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
ASKER
I'm moving steadily forward following the instructions at https://raid.wiki.kernel.org/index.php/RAID_setup. I'm deferring doing the boot drive for the moment (one thing at a time!). I've create the RAID array as:
mdadm --create /dev/md0 --metadata 1.2 --verbose --level=6 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1
This took 21 hours! Is that normal or do I just have a pathetically slow system? These are 2TB drives.
I then made the file system as:
mke2fs -v -m .1 -b 4096 -E stride=128,stripe-width=38
which went rather quickly -- 10 minutes-ish. Then, I started the RAID:
mdadm --assemble --scan --uuid=39edeb69:297e340f:0
Despite the abundant information in that link, it really doesn't tell me what do do next. Just mount the file system? I made that assumption and did:
mount /dev/md0 /mnt/RAID
is that sufficient? I'm going to assume it is and start copying data to the drive. I expect that will take a very long time, so if someone can reply as to what my next step should be in the meantime, I'd apprecate it. That way, I can blow off the copying and do whatever should be done.
THX
mdadm --create /dev/md0 --metadata 1.2 --verbose --level=6 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1
This took 21 hours! Is that normal or do I just have a pathetically slow system? These are 2TB drives.
I then made the file system as:
mke2fs -v -m .1 -b 4096 -E stride=128,stripe-width=38
which went rather quickly -- 10 minutes-ish. Then, I started the RAID:
mdadm --assemble --scan --uuid=39edeb69:297e340f:0
Despite the abundant information in that link, it really doesn't tell me what do do next. Just mount the file system? I made that assumption and did:
mount /dev/md0 /mnt/RAID
is that sufficient? I'm going to assume it is and start copying data to the drive. I expect that will take a very long time, so if someone can reply as to what my next step should be in the meantime, I'd apprecate it. That way, I can blow off the copying and do whatever should be done.
THX
ASKER
Problem ... I don't seem to have the right settings in /etc/fstab. In fstab I have
/dev/md0 /mnt/RAID ext2 defaults,uid=99 1 1
but when I try to mount it I get:
mount: wrong fs type, bad option, bad superblock on /dev/md0,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
I can mount w/o the uid=99, but I need to have the folder owned by 99 (nobody) to samba mount it. This may not be a RAID specific question, but any ideas? I'm stuck not being able to copy data to the RAID.
/dev/md0 /mnt/RAID ext2 defaults,uid=99 1 1
but when I try to mount it I get:
mount: wrong fs type, bad option, bad superblock on /dev/md0,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
I can mount w/o the uid=99, but I need to have the folder owned by 99 (nobody) to samba mount it. This may not be a RAID specific question, but any ideas? I'm stuck not being able to copy data to the RAID.
ASKER
duh! never mind on that last permissions question. I simple had to change the permissions on the mountpoint itself! So, please refer back to posting ID: 39209796.
Mainly, I'd like to know if there is something else I need to do for this RAID to function properly other than simply mounting it.
Mainly, I'd like to know if there is something else I need to do for this RAID to function properly other than simply mounting it.
ASKER
This question seems to have grown stale as I've posted 4 comments with no reply; probably because I've wandered from the original question about using RAID for the boot device. So, I'm going to close this one out and refer interested experts to a new link I've posted specifically addressing my last comment in this question: https://www.experts-exchange.com/questions/28145407/how-to-start-stop-dev-md0-RAID-devices.html
As to the original boot/RAID issue, I've done more research. There is an extensive discussion of this at https://raid.wiki.kernel.org/index.php/Tweaking,_tuning_and_troubleshooting#Making_the_system_boot_on_RAID. This seems quite a bit more complex that dlethe's response in ID: 39204947, above. I'm going to experiment with this on a computer lab rat before attempting to configure this on a production machine.
I have an ASUS P8Z77-V LK motherboard that advertised RAID support on the box, but after reading the user guide it appear that I have to create a Windows driver onto a floppy disk to support this. Since I have neither Windows nor a floppy drive, this is not an option (it seems to me that it should be rather simple to create a RAID-1 with an on-board SATA controller, but what do I know).
Therefore, for the time being, I've resorted to my old standby, a "latent" mirror. I.e., once a day (or so) I copy everything from the main drive to an offline backup drive -- even properly lilo'ing the backup drive. Once a month, I wipe the backup drive with mkfs and start fresh. This works fine except that, in case of main drive failiure, I have to manually swap the drives (or cables) to boot off the backup, and I'll lose whatever files were created/modified since the most recent "mirror" backup unless they were backed up elsewhere.
End of saga ... for now.
As to the original boot/RAID issue, I've done more research. There is an extensive discussion of this at https://raid.wiki.kernel.org/index.php/Tweaking,_tuning_and_troubleshooting#Making_the_system_boot_on_RAID. This seems quite a bit more complex that dlethe's response in ID: 39204947, above. I'm going to experiment with this on a computer lab rat before attempting to configure this on a production machine.
I have an ASUS P8Z77-V LK motherboard that advertised RAID support on the box, but after reading the user guide it appear that I have to create a Windows driver onto a floppy disk to support this. Since I have neither Windows nor a floppy drive, this is not an option (it seems to me that it should be rather simple to create a RAID-1 with an on-board SATA controller, but what do I know).
Therefore, for the time being, I've resorted to my old standby, a "latent" mirror. I.e., once a day (or so) I copy everything from the main drive to an offline backup drive -- even properly lilo'ing the backup drive. Once a month, I wipe the backup drive with mkfs and start fresh. This works fine except that, in case of main drive failiure, I have to manually swap the drives (or cables) to boot off the backup, and I'll lose whatever files were created/modified since the most recent "mirror" backup unless they were backed up elsewhere.
End of saga ... for now.
ASKER
Thanks for the comments
ASKER