Rick Stevens wrote: > On Thu, 2007-08-09 at 18:58 -0500, Mikkel L. Ellertson wrote: >> From what I understand, there are a max of 16 device entries created >> for a SCSI hard drive. (sdx and sdx1 through sdx15) So while you can >> have more partitions then that, Linux will not let you access them >> when using the SCSI code to access the drive. I believe it is a >> driver problem more then a udev problem. > > Well, the "x" in your example can take the RE form "[a-z]+". For > example, we have some storage arrays with, oh, 130 LUNs on them. They > appear as /dev/sda[1-15] through /dev/sdiv[1-15] > > As far as the partition numbers, that's based on the minor number of the > block device. The formula is "(16 * drive number) + partition number". > The "16" is what limits it to 16 partitions (with partition 0 being the > same as the whole drive, e.g. "/dev/sda0" is the same as "/dev/sda"). > > "man sd" will show you the magic. > You and I are saying the same thing, just in different ways. I used x where you use [a-z]+. But I have never seen /dev/sda0 created. It is always /dev/sda. You could also argue that the entire disk is not a partition, even though you can access the entire disk as if it were a partition. (You can create a file system on /dev/sda, but you can not do that and have a partition table at the same time.) There have been times in the past where I have used the entire drive instead of creating a partition table. But most BIOS do not like it. (Tar doesn't care - the drive can be one big archive.) When you get into SCSI LUNs, you will probably lose a lot of people. I have always found it easier to think of each LUN as its own device. But then again, I worked more with CD drive arrays connected to a LUN controller. 8 drives using one SCSI device number. Now days, it usually works better to copy the CD images to a hard drive, and loopback mount them. By using automount to manage them, you can even keep the number of loopback mounts down to a reasonable number. Mikkel -- Do not meddle in the affairs of dragons, for thou art crunchy and taste good with Ketchup!
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