Hardware Raid 5

I want to install a raid controller in my ScoUnix box. I Have 4 hard drive inside, 1 for Unix and 3 for data. I want to do my raid 5 with my 3 data drive. I would like to know if I need to reinstall Unix even if it'snot a part of my raid configuration
christgAsked:
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jmohanConnect With a Mentor Commented:
If you are going to replace the existing SCSI controller with your new RAID controller, then you need to reinstall SCO.

If you are going to install RAID controller as your secondary controller (primary being the existing SCSI controller)..
      There are few things you need to note ..
      1. Disk 0 - root/swap/tmp ...only and nothing else
      2. Disk 1,2,3  I condider this as your DATA
      3. Proper backup. Be 100% sure that you can fall back to you original configuration.
      4. SCO drivers for the other RAID controller.

      unmount the partitions for Disk 1,2&3 & also update you /etc/mnttab
      delete the disks ID1,2&3 (use mkdev hd)
      you need to know SCSI ID, LUN of these disks.
      Rebuild & reboot to ensure what you did is working.
      You should only see the UNIX (disk0) and not the other disks (DATA).

      Now install the RAID controller as secondary SCSI controller
      Now use your HW vendor supplied RAID config utility & configure the Disks 1,2,3

      Boot with SCO
      Install the RAID controller Driver
      Rebuild & reboot
      run mkdev hd, add Disk
      this will rebuild and reboot.
      run mkdev hd again, create partitions
      mount the partitions
      update your mnttab  
      reboot & check it works.
      Restore from your back the DATA alone.
Whenever, you pull out a RAID configured disk, you need to run the Vendor supplied utility to rebuild the disk agian.
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procguyCommented:
No you won't have to reinstall Unix.  You will have to back up the data and re-install that once the RAID is setup and the partions are created.  On the UNIX side, you'll have to obtain the appropriate device driver for the controller, tune some kernel parameters & recompile it, and change the fstab file.
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jcondeCommented:
Hi, first of all, if you want to install a raid 5 configuration, and you have 4 hard disks, one of them will work as a "hot point" drive....that means you will not be able to use it.  That drive will be on a stand-by basis and will become active when one of the other 3 fail.

Now, you will have to reinstall the OS because the raid setup will make you have to low-level format the hard drives.

Before installing the DPT card, make sure you have the correct drivers for Sco.

Regards,

Jorge del Conde
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jcondeCommented:
oops, it's not called "hot point" drive, but Hot-Spare drive.
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fire85Commented:
You don't necessarily need to have a hot spare drive, but it does make recovery easier because you can put the hot spare online if a drive fails and rebuild the stripe. Otherwise you will need to obtain another drive equal to the size of the current drives if one does fail and go offline.
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jmohanCommented:
Christg,
Are you going to use SCO Virtual Disk Manager or is it a Hardware RAID ?
What version of SCO Unix?
If its SCO Virtual Disk Manager, which version?
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jmohanCommented:
Oops...missed to note the Subject!
Believe its Hardware RAID 5 (from the Subject).
Let us know how your existing SCO is partitioned. i.e. on which controller the 4 HDDs are installed? Is this the RAID controller?
Do you have the config. utility for the RAID controller?

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christgAuthor Commented:
Hi, the SCO Version is 5.0.4 and I will use hardware Raid. Right now, all disk are installed on a regular SCSI controller. I want to keep the first hard drive (Sco is installed on it) and have a raid 5 with the 3 other hard drive.
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jmohanCommented:
Chris,
If you are going to replace the existing SCSI controller with your new RAID controller, then you need to reinstall SCO.

If you are going to install RAID controller as your secondary controller (primary being the existing SCSI controller)..
There are few things you need to note ..
1. Disk 0 - root/swap/tmp ...only and nothing else
2. Disk 1,2,3  I condider this as your DATA
3. Proper backup. Be 100% sure that you can fall back to you original configuration.
4. SCO drivers for the other RAID controller.

unmount the partitions for Disk 1,2&3 & also update you /etc/mnttab
delete the disks ID1,2&3 (use mkdev hd)
you need to know SCSI ID, LUN of these disks.
Rebuild & reboot to ensure what you did is working.
You should only see the UNIX (disk0) and not the other disks (DATA).

Now install the RAID controller as secondary SCSI controller
Now use your HW vendor supplied RAID config utility & configure the Disks 1,2,3

Boot with SCO
run mkdev hd, create partitions, rebuild and reboot.
update your mnttab
reboot & check it works.
Restore from your back the DATA alone.

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christgAuthor Commented:
The answer of jmohan is better
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