Could someone shed some light on a couple of things which are 
confusing me, please?

Here's part of dmesg's output which describes the hard disks attached 
to a 3000/400 running 2.0G:

sd0 at scsibus0 target 0 lun 0: <DEC, RZ1CF-AF (C) DEC, 1614> disk fixed
sd0: 4091 MB, 3708 cyl, 20 head, 113 sec, 512 bytes/sect x 8380080 sectors
sd0: sync (200.00ns offset 15), 8-bit (5.000MB/s) transfers, tagged queueing
sd1 at scsibus0 target 1 lun 0: <DEC, RZ1CF-AF (C) DEC, 1614> disk fixed
sd1: 4091 MB, 3708 cyl, 20 head, 113 sec, 512 bytes/sect x 8380080 sectors
sd1: sync (200.00ns offset 15), 8-bit (5.000MB/s) transfers, tagged queueing
sd2 at scsibus1 target 0 lun 0: <COMPAQ, ST15150N, 5217> disk fixed
sd2: 4094 MB, 3712 cyl, 21 head, 107 sec, 512 bytes/sect x 8386000 sectors
sd2: sync (200.00ns offset 15), 8-bit (5.000MB/s) transfers, tagged queueing
sd3 at scsibus1 target 1 lun 0: <SEAGATE, ST15150N, 8602> disk fixed
sd3: 4095 MB, 3712 cyl, 21 head, 107 sec, 512 bytes/sect x 8388315 sectors
sd3: sync (200.00ns offset 15), 8-bit (5.000MB/s) transfers
sd4 at scsibus1 target 2 lun 0: <SEAGATE, ST15150N, 0023> disk fixed
sd4: 4095 MB, 3712 cyl, 21 head, 107 sec, 512 bytes/sect x 8388315 sectors
sd4: sync (200.00ns offset 15), 8-bit (5.000MB/s) transfers
sd5 at scsibus1 target 4 lun 0: <SEAGATE, ST15150N, 0023> disk fixed
sd5: 4095 MB, 3712 cyl, 21 head, 107 sec, 512 bytes/sect x 8388315 sectors
sd5: sync (200.00ns offset 15), 8-bit (5.000MB/s) transfers
sd6 at scsibus1 target 5 lun 0: <SEAGATE, ST42100, 8224> disk fixed
sd6: 1812 MB, 2574 cyl, 15 head, 96 sec, 512 bytes/sect x 3711990 sectors
sd6: sync (200.00ns offset 15), 8-bit (5.000MB/s) transfers, tagged queueing

Originally the machine had two disks, sd0 and sd1, which were 
configured into a RAID 1 bootable array using RAIDframe.  Later sd2 
thru sd5 were added in a RAID 5 array, again with RAIDframe, then sd6 
as a stand-alone drive.

sd2 failed so I bought another ST15150N on ebay (the new sd2 is shown 
above).  I was surprised to see it probed as a Compaq not Seagate, 
and more surprised to see it has fewer sectors than the other 
ST15150N's even though it has the same number of cylinders, heads and 
sectors.  Any idea how that could be?  (Do the digits following the 
model numbers indicate the firmware version?)

Then I noticed the number of sectors for all the disks but sd0 and 
sd1 are not equal to the product of their number of cylinders, heads 
and sectors.  So, my assumption that should be so is obviously 
incorrect.  Is there a way to reconcile these values?

I guess creating a RAID partition spanning all the new sd2's sectors 
and attempting to integrate it into the RAID 5 array with

# raidctl -R component0

would result in failure (and the machine crashing?) because the other 
component's RAID partitions go from sector 0 to sector 8388315?


Ray