UNIX for Beginners Questions & Answers

We have a legacy system that runs on SCO OpenServer 5.0.6, and I've rebuilt the server a couple of times so we can have access to old historical data. That system suddenly went offline for no known reason, and I know that the configuration has not been altered, there is nobody with access to the root login except for me, and there have been no changes. The current problem does not appear to be with the hard drive, as in past problems I have dealt with. When the system starts up I can see that it "finds" and lists the IDE drive, and it will come to the "Boot:" prompt. When I hit "Enter" at the boot prompt, like normal, it goes through about one screen of the loading process, and then it just goes blank, and I get a "no signal" notification on the monitor, and the machine restarts. I have tried entering "unix.old" at the boot prompt, but is still does the same thing. Then I read somewhere online to try "unix.safe" at the boot prompt, and this got me further. It looked like it was going to take me all the way to a login prompt, but then it stopped and this error showed up on the screen:


Open event driver failed.... Fatal server error.... Check mouse configuration


So I thought maybe something happened to the mouse, and I plugged a different one in but it still does the same thing. Like I said I know that there was no change made to any mouse configuration in the O/S, so what can I try now? I would appreciate any and all suggestions about how I can get this system back up and running. Thanks.

You say that you rebuilt the server a couple of times so I guess that you have installation media? Or do you have a root & boot floppy set? Either way, you should be able to boot the system into a (root) shell, mount the hard disk root filesystem and take a look around (and run fsck on that filesystem to check its integrity).

OK, I tried booting into unix.safe again, only this time I entered Single User (maintenance) mode and it allowed me to login as root. It shows that the / and /stand file systems are mounted. Now I want to be careful, does the "fsck" command just check the file system, or does it attempt to repair? I ask this because - whenever I have booted this machine for the past 15 years it has come up with the message that "the root file system needs checking..." but I always say "no" because I seem to recall that when I said "yes" (and this was back when the system was actively used) it created some type of error and I had to restore the whole think from backup. I do not want to have that happen again, so whatever I try now I would prefer not to lose data. Is it save to proceed with the "fsck" command on the root file system without anything "dangerous" happening? Also can you give me the syntax to run the command properly? Thanks!

The way to fsck a filesystem without anything dangerous happening is to use the -n switch:

Code:

# fsck -n <filesystem#>

with the -n meaning, whatever the question is the answer is no. Therefore, no modifications/corrections to the filesystem but the extent of any damage will be shown.

The opposite is:

Code:

# fsck -y <filesystem>

which means all questions are automatically answered yes meaning correct everything, and yes, in the case of severe damage, can destroy the filesystem completely.

If damage is limited then you can run fsck again with neither -n or -y and answer each question yourself individually to carry out corrections.

I was able to run the fsck on the root file system, and there is apparently some damage. Here are the errors that I'm getting:


At beginning: Cannot Read: BLK 269191880


Then: FOLLOWING DISK SECTORS COULD NOT BE READ: 269191880, 269191881
Cannot Read block bitmap (logical block 134595940)


At Phase 4: FREE INODE COUNT WRONG IN SUPERBLK


At Phase 6: FREE BLK COUNT WRONG IN SUPERBLK


Since I used the -n switch no repairs were attempted. Since the system will not boot up regularly, am I to assume the bad sectors are affecting my kernel or something that is needed to boot up? If I try to run fsck with -y switch, or try to run interactively to fix errors, will I trash the system and need to reinstall and restore data from backup?


I have done the restore before so I know how, but I also know it is risky due to the age of my backup tape and drive. If it is the only way I will have to try, but is there a chance that repairing the disk using fsck will fix everything? Thanks

Well, good news and bad news.

Good news....the damage is very very minor and you should be able to fix that with an interactive fsck run. There should only be a few questions (to answer 'y' to each) and it is very unlikely anything will go wrong with that, but if it does and you are getting many more questions than expected, you can break out of it and stop the process. You can't do that if you run it '-y' because everything will happen too fast.

Bad news....the damage is so minor that it could well NOT be the reason for it not booting. However, it might be.

Hi,

This looks to me like a head crash on the system partition, there are a couple of things that you could try - but I don't hold out much hope I'm afraid.

You could boot the system from a bootable floppy and use "divvy" to have a look at the disk and reassign the cylinder - might work.

My next option would be to replace the disk and rebuild.

Or you could virtualise the whole thing on something a bit more modern - under VMware perhaps?

Regards

Gull04