Configuring The Storage Unit; Configuring The Storage Unit For An Intel Host Running Linux; Partitioning Storage Unit Disks For An Intel Host Running Linux; Example Of Range Of Devices For A Linux Host - IBM TotalStorage DS6000 Attachment Manual

parameter when the kernel compiles. Traditionally, this value has been 40, but
newer Red Hat kernels have it set to 128 or 256. On SUSE SLES 9 the dynamic
configuration system eliminates this limit.
For example, consider a system with an internal SCSI Adaptec host adapter and
one disk. The system contains fibre-connected disks and a
CONFIG_SD_EXTRA_DEVS parameter set to 40. The Adaptec host adapter driver
loads first and configures the single attached disk. At this point, the system is
limited to a total of 41 SCSI disks instead of the full 128 or 256. If there are more
than 40 disks visible in the fibre-channel fabric, the system configures and uses
only the first 40. All of the fabric devices might be listed in the /proc/scsi/scsi
directory, but only the first 40 are configured with the SCSI disk driver. You are
more likely to encounter this constraint in multipath fabric situations.

Configuring the storage unit

This section provides instructions for configuring the storage unit.

Configuring the storage unit for an Intel host running Linux

Configuring the storage unit for an Intel host running Linux
Each of the attached storage unit LUNs has a special device file in the Linux
directory /dev. There are maximums of 128 or 256 fibre-channel disks that are
based on the major numbers that are available. For Red Hat, the operating system
automatically adds the entries for all 128 devices. For SUSE, there are only special
device files for the first 16 disks. You must create the device files for additional
disks by using the mknod command.
The range of devices goes from /dev/sda (LUN 0) to /dev/sddx (LUN 127).
Figure 54 shows an example of the range for the devices.
Figure 54. Example of range of devices for a Linux host

Partitioning storage unit disks for an Intel host running Linux

Partitioning storage unit disks for an Intel host running Linux
Before you create a file system, partition the disk by using the fdisk utility. You have
to specify the special device file of the disk you want to partition when executing
fdisk. Figure 55 on page 110 shows an example of the different options for the fdisk
utility.
# ls –l /dev/sda
brw-rw---- 1 root disk 8, 0 Aug 24 2000 /dev/sda
Chapter 11. Attaching to an Intel host running Linux
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