I'm using the "dmraid" and device-mapper in Linux version 2.6.17 to support my Promise RAID array. Everything works fine, with the exception of one minor annoying error during boot. Since the partition tables on the hard disks are actually RAID metadata, Linux complains about the partition table being invalid for devices "sda", "sdb", "sdc" and "sdd". So far as I can tell that causes no harm, but the error message is annoying. When I run "dmraid" it recognizes the metadata and correctly sets up the RAID volume in "/dev/mapper".

I've looked at the kernel parameters and SCSI hard disk driver parameters and can find no mention at all about any way to disable the kernel or driver trying to detect a partition table. In this case, I know the partition table will never look valid, and no partitions need to be created. Is this something that I need to disable by editing the driver source, or is there an option for the kernel or SCSI disk driver to disable that.

Any suggestions would be appreciated.

Well, I found out that Linux now uses the number of minor device IDs for a block device to determine if it should check for partitions. Most block devices seem to have that hard coded.

If the number of minors is 1 then Linux doesn't check for partitions. That's because one minor ID is used to reference the entire disk device, and the rest are used for partitions. If the number of minors is greater than 1 then Linux does check for partitions.

The SCSI disk driver handles many of the SATA controllers like the one I have. The SCSI disk driver "sd.c" has the number of minor devices hard coded to 16, so it will always check for partitions on every SATA disk or SCSI disk.

Now that detection of partitions has been moved from each individual driver into a central module, it would be helpful to have a kernel option to disable partition detection on named disk devices. It's possible to disable probing, but I'm assuming that will prevent the disk drive from being detected by the driver at all.

In my case, I can patch the SCSI disk driver to disable support of partitions, but I think I'm just going to ignore the error.