On Sat, 21 Nov 2009 21:43:30, Marco Peereboom wrote: When possible use hardware RAID. ... ami is ok but has some issues.
----- So, since I have hardware RAID, let's stick with it. Now, what if it fails. ----- On Sat, 21 Nov 2009 22:54:58, Nick Holland wrote: There is more to RAID1 than duping the data to two drives and keeping them the same. All HW RAID systems that I have seen use some kind of signature to mark the drives as part of a RAID set ... The signature that helps resolve the above has to be somewhere on the disk. Some systems try to hide it some place the OS would never notice (I believe I read some tech notes on one system that stuck it on the very last sector of the disk, with the assumption that very few OSs ever put anything there, I've seen one other RAID system that seemed to do that, as the drives COULD be removed from the RAID system and used directly on a standard controller), but others just plop it at the front of the physical disk, and create the array in the remaining space. ----- Thanks for the insight. So, I decided I would look more closely at this situation, and see if there was a way to recover one of the RAID disks when it was attached to a regular SATA controller. In my particular case, this turned out to be easier than I expected, for reasons that I really don't understand, mostly because my last email was inaccurate. Anyway, in short. I again disconnected one of the drives from the RAID array, and connected it directly to one of the motherboard's SATA controllers. As before, when I tried to boot the system, I would get a "No O/S" message from the BIOS when it would try to boot from the hard disk. It appears, on this machine, that when the SATA controller is on with a disk connected, that's the drive it tries to boot, and does not try the IDE drive that is connected with the O/S on it. So, I booted up with the 4.6 Install CD, and used the shell provided. As I said before, fsck did not work. Also fdisk and disklabel returned "device not configured." I had assumed that this was because the RAID disk attached to the SATA controller was not readable. But then I noticed that fdisk and disklabel were able to read both the main openbsd system disk (wd0), and the degraded raid array (sd0), but not the SATA attached RAID disk (wd2) OR the secondary IDE disk present (wd1). This was odd, since both wd0 and wd1 are fine when the system boots from the installed IDE hard disk. (BTW, I could find no indication in the man pages or elsewhere to suggest that disklabel or fdisk work differently in the shell provide by the install CD - this is the part I don't understand.) Therefore, I rebooted, this time using the CD to start the boot process, but then pointed it at the installed system on wd0. When it came up, I was able to log in, and the SATA connected RAID disk was there. I could see the disklabel; the filesystem was clean; and all the files were there when I mounted it. (It appears the signature is somewhere where it does not interfere with the OS for the MegaRaid controller.) As I said, I don't know why the install CD did not work. But, I really want to say thanks for all the insight that I got from everyone. I had not even thought about the controller failing, and, if it had, I would have probably been mighty annoyed, and may have decided my data was gone for good (this would have probably also annoyed my user base -> wife). But now, I know that in this situation (with this controller and a RAID1 array), if the controller ever dies, I can recover the data by connecting the disk to a regular SATA controller; and I know the steps I would need to take. I still don't understand why it does not work directly from the 4.6 Install CD, however. Thanks again Bye - ted PS: And I still have the off-site backup in case the house burns down.
