weird raid issue

[ub007]

Hi

I have a raid 6 configuration comprising of twelve 500GB sata drives.
1 of them failed and I replaced it with a 750GB drive as i couldnt find a spare 500g one.
At that point i decided to start fresh rather than wait for raid rebuild to occur. So deleted the raid array and re-created it. Then created filesysystem and mounted raid. All went well. However I then rebooted the server. This time raid went missing, as in it didnot mount the raid automatically ( I had configured it to do so and used to work prior to replacing the 500g with a 750 ). So I had to issue a mount request manually. Tested this many times with same result. So it appears that there are some checks goingon before it mounts the raid and it doesnot like the new config of 500 + 750g disks and it fails the automount.

Any thoughts on what could be goingon here?
wish to know at a linux low level, are there any specific checks that could be failing the mount?

Thanks
David

[Rubberman]

Some information about the Linux distribution you are using, as well as hardware, and whether you are using hardware or software RAID.