IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

Chapter 7. Open systems servers - UNIX 225

features of SDD. When removing SDD, you can move the volume group devices back to disk

devices using the vp2hd command.

7.6.2 Sun Solaris SDD commands

SDD for Solaris adds the specific commands shown in Table 7-4.

Table 7-4 Solaris SDD commands

On Sun Solaris, SDD resides above the Sun SCSI disk driver (sd) in the protocol stack. For

more information about how SDD works, refer to 5.6, “Subsystem Device Driver (SDD) -

multipathing” on page 157. SDD is supported for the DS6000 on Solaris 8/9.

Some specific commands SDD provides to Sun Solaris are listed below as well as the steps

to update SDD after making DS6000 logical disk configuration changes for a Sun server.

cfvgpath

The cfgvpath command configures vpath devices using the following process:

򐂰 Scan the host system to find all DS6000 devices (LUNs) that are accessible by the Sun

host.

򐂰 Determine which DS6000 devices (LUNs) are the same devices that are accessible

through different paths.

򐂰 Create configuration file /etc/vpath.cfg to save the information about DS6000 devices.

򐂰 With the -c option: cfgvpath exits without initializing the SDD driver. The SDD driver will be

initialized after reboot. This option is used to reconfigure SDD after a hardware

reconfiguration.

򐂰 Without the -c option: cfgvpath initializes the SDD device driver vpathdd with the

information stored in /etc/vpath.cfg and creates pseudo-vpath devices

/devices/pseudo/vpathdd*.

Command Description

cfgvpath Configures SDD vpath devices. Updates the information in

/etc/vpath.cfg and /etc/vpathsave.cfg. The -c option updates the

configuration file. The -r option updates the device configuration

without a system reboot.

defvpath Second part of the cfgvpath command configuration during startup

time.

datapath SDD driver console command tool.

rmvpath [-all, -vpathname] Removes SDD vpath devices from the configuration.

get_root_disks Generates a file called /etc/vpathexcl.cfg to exclude bootable disks

from the SDD configuration.

vpathmkdev Creates files links in /dev/dsk and /dev/rdsk.

showvpath Lists the configuration mapping between SDD devices and

underlying disks.

pathtest Debug tool.

226 IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

vpathmkdev

The vpathmkdev command creates files vpathMsN in the /dev/dsk/ and /dev/rdsk/ directories

by creating links to the pseudo-vpath devices /devices/pseudo/vpathdd*, which are created by

the SDD driver.

Files vpathMsN in the /dev/dsk/ and /dev/rdsk/ directories provide block and character access

to an application the same way as the cxtydzsn devices created by the system. The

vpathmkdev command is executed automatically during SDD package installation and should

be executed manually to update files vpathMsN after hardware reconfiguration.

showvpath

The showpath command lists all SDD devices and their underlying disks. An example of the

showpath command is displayed in Example 7-23.

Example 7-23 Sun Solaris showpath command output

# showpath

vpath0c

c1t8d0s2 /devices/pci@1f,0/pci@1/scsi@2/sd@1,0:c,raw

c2t8d0s2 /devices/pci@1f,0/pci@1/scsi@2,1/sd@1,0:c,raw

Changing an SDD hardware configuration in Sun Solaris

When adding or removing multi-port SCSI devices from a Sun Solaris system, you must

reconfigure SDD to recognize the new devices. Perform the following steps to reconfigure

SDD:

1. Shut down the system. Type shutdown -i0 -g0 -y and press Enter.

2. Perform a configuration restart. From the OK prompt, type boot -r and press Enter.

This uses the current SDD entries during restart, not the new entries. The restart forces

the new disks to be recognized.

3. Run the SDD configuration utility to make the changes to the directory /opt/IBMdpo/bin.

Type cfgvpath -c and press Enter.

4. Shut down the system. Type shutdown -i6 -g0 -y and press Enter.

5. After the restart, change to the /opt/IBMdpo/bin directory by typing cd /opt/IBMdpo/bin.

6. Type devfsadm and press Enter to reconfigure all the drives.

7. Type vpathmkdev and press Enter to create all the vpath devices.

For specific information about SDD commands, check IBM TotalStorage Multipath Subsystem

Device Driver User’s Guide, SC30-4096.

Note: cfgvpath without the -c option should not be used after hardware reconfiguration,

since the SDD driver is already initialized with the previous configuration information. A

reboot is required to properly initialize the SDD driver with the new hardware configuration

information.

Tip: Note that you can use the output from showvpath to modify iostat or sar information

to report stats based on vpaths instead of hdisks. Gather iostats to a file, and then replace

the disk device names with the corresponding vpaths.