Topic: Recovering from a Raid 1 disk failure

[Mike Drummond]

SME 5.1.2
I am attempting to follow the recovery process setout in the recovery how to.  /dev/hdc has failed and been replaced.   Unfortunately I was unable to get an identical 20GB disk.  The replacement disk is 20GB but a Maxtor rather than a Quantum.  Both drives are set to autodetect in the bios. I am trying to set up identical partitions on the new hdc.  The how to simply says use "fdisk /dev/hdc"  how ever at this point I have a number of choices for which I need some assistance.

fdisk -l /dev/hda  outputs .....

Disk /dev/hda: 255 heads, 63 sectors, 2498 cylinders
Units = cylinders of 16065 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hda1   *         1        33    265041   fd  Linux raid autodetect
/dev/hda2            34      2498  19800112+   5  Extended
/dev/hda5            34        35     16033+  fd  Linux raid autodetect
/dev/hda6            36      2498  19784016   fd  Linux raid autodetect

fdisk -l /dev/hdc  outputs .....
Disk /dev/hdc: 16 heads, 63 sectors, 39535 cylinders
Units = cylinders of 1008 * 512 bytes

I assume I am to setup a primary partition numbered 1 and an extended partition numbered 2?. Following this setup logical partitions within the extended partition.

Now how do I translate the start/end block numbers for the new drive as the drives are different?

Any pointers would be most appreciated

Regards Mike Drummond

[John Crisp]

Mike,

Don't know whether I can help but I've done similar a few times. The thing that I am not sure about is the HD geometry that you show. Can you check this out again ?

Last time I did it I replaced a 40 with a 60, ignored the geometry settings (for better or worse) and followed the Raid Recovery howto for importing the partition table to the new disk which worked fine for me. You could give it a try - the worst it will do is report an error when trying to install the new partition on the new drive.

One thing to remember is that apparently lilo does not by default make both drives independantly bootable. There is some stuff on this in the forums. Have a search.

Let me know how you get on.


B. Rgds
John

[Mike Drummond]

Thanks for the prompt on the rebuild I tracked down the instructions you were referring to and they were much better than the SME how to  I had.  

Yes that is the drive geomentry as reported by fdisk.  However in the bios the units have identical  H,C,S figures.  I have determined that the Maxstor 20GB drive is slightly smaller than the Quantum one.  

I have given up on getting this disk into the array.  I moved the files from the Ibays to a PC. Then did a backup to desktop.

I tried a fresh install of SME 5.1.2 this caused more issues.  If either drive is installed and software raid is not chosen the install goes ok.  I have 19GB of available disk space.  Now if both drives are back in the server and I install SME as software raid I only get 9GB of disk space and on boot an error message saying something about the mirrored partitions being on the same HDD.  I can also replicate this problem under SME 5.6.   If I do a standard RH 7.3 install it picks up that the drive geomentry of the Maxtor may not be being recognised correctly and gives a warning message.

To further compound the problem the restore from desktop fails with out an error message.  The system could not display the updated web page following pressing the restore button.  I tried this three times by then it was 2am in the morning .  

I am now off to by two new identical HDD ( At least I can now upgrade the drives to 60GB models) and will try rebuilding the server tonight.

I am now  wondering if SME 5.6 will support my highpoint IDE raid controller.  I removed it from the server as I could not get previous versions of SME to install on it.  If I can get the highpoint controller to work I can then drop the software raid.

Thanks for your suggestion

Regards
Mike Drummond