Using RAID on Solaris

How does RAID function on a normal Solaris install. If I used hardware or software RAID on a Solaris box and I was installing from scratch, how would the mount points be created on a RAID 5 setup? Usually, I believe, the mount points are created on a seperate disk.

Also, what would be the best solution if the RAID array failed and I had to do a restore?

I have worked extensively with RAID on NetWare and Windows, but never Solaris.

Thanks in advance.
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shanechambersConnect With a Mentor Commented:
Typically how I due this;

Step 1: Build the root partition, and filesystem.  Like I said before I don't stripe root (mirror is available, afterwards).  Since I've got a whole disk for root, I go ahead and place other system dependent filesystems (var, usr, usr/openwin, opt, maybe home, or export) on that same disk.  Basically you have a full system on one disk.

Step 2: Build the meta-devices.  I presume you've got some specific data you want to use this machine for.  That data is probably pretty important, and might change allot, so therefor you want to stripe the disks, to protect that data.  In my setup, I would place all _that_ data on the  meta-device(s).  (You can play with metatool, and/or look over the Answerbook pages on meta-devices to see how to do that, also give serious consideration to adding a hot-swap drive to the configuration)

Step 3: Build a filesystem on each meta-device. (newfs)

Step 4: Copy the data in.


You would do a backup of each filesystem, and meta-device the same way, ufsdump.  I.E.;

# Backup of a normal filesystem
ufsdump 0cfu /dev/rmt/0n /dev/dsk/c0t8d0s0
# Backup of a meta-device
ufsdump 0cfu /dev/rmt/0n /dev/md/dsk/d1


In the event of a complete loss, you would boot from CDROM, repartition out the root drive, newfs the partitions, and restore the system directories from tape.  Once you had that, you would boot the system normal (making sure to comment out the meta-device from /etc/vfstab, so you don't have problems tying to mount filesystems that don't exists), and recreate the meta-devices.  Once they are layed out, and newfs'd, you can restore from tape again.

In the event of a loss of disk from the array, replace the disk, and use metatool to rebuild the lost information.

(by the way, you're getting a bargin for 50 pts :)
I believe what you are looking for is a meta-device.  You can setup, and administer a RAID configuration by running 'metatool,' found in the SUNWmd package (for Solaris 7, and I think 2.6 as well).

Basically, you would stripe you disks, creating a meta device.  That meta device is what you would then mount.
bugsuperstar37Author Commented:
Would I have to create multiple meta-devices to mount /usr /opt and of course / ?
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First off, I don't typically stripe the root filesystem.  You might want to mirror it, but striping root gets (in my opinion) a little hairy.

I believe what you're asking is "for each filesystem, would I have to create another meta-device?"  If that's the case, yes you would.  A meta-device is basically a big psydo-partition that is composed of several smaller physical partitions (slices), instead of just one.  

Just like a normal partition, once the meta-device is made, you would have to run 'newfs' on the meta-device to make a filesystem out of it.

Does that answer your question, or am I being too general?
bugsuperstar37Author Commented:
That helps, but how would this be done on a new install if it is software RAID?

Also, how would I restore if this system failed? UFSRESTORE if I backed up using UFSDUMP? Would I have to reinstall a system that resembled the one that failed and then restore?
bugsuperstar37Author Commented:
You are right, this is great info. Point increased to 100.
bugsuperstar37Author Commented:
Thank you. I greatly appreciate your help.
Hey, glad I could help.

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