Configuring device I/O processing time

You can reduce the time that is needed to complete jobs that have substantial I/O by changing the device database file.

You can shorten the processing time of large I/O directed to one disk array unit by completing the two procedures described in Procedure A and Procedure B. Both procedures must be completed for this operation to be successful.

Procedure A

Procedure A applies to Tru64 UNIX version 4.0 and later. For more information, see the Tru64 UNIXddr.dbase and ddr_config manual files.

Complete the following steps to set up the Tru64 UNIX device parameter database for features that are specific to the Lenovo Storage V series system:

  1. Quiesce the storage.
  2. Place the host system in single-user mode as root.
  3. Edit the /etc/ddr.dbase file by including the following lines as an entry in the DISKS subsection:
    SCSIDEVICE
        #
        # Values for the IBM 2076 [2145]
        #
        Type = disk
        Name = "IBM" "2145"
        #
        PARAMETERS:
            TypeSubClass        = hard_disk, raid
            BadBlockRecovery    = disabled
            DynamicGeometry     = true
            LongTimeoutRetry    = enabled
            PwrMgmt_Capable     = false
            TagQueueDepth       = 20
            ReadyTimeSeconds    = 180
            CMD_WriteVerify     = supported
            InquiryLength       = 255
            RequestSenseLength  = 255
  4. Compile the ddr.dbase file by issuing the following command:

    ddr_config –c

  5. Confirm the values by issuing the following command:

    ddr_config –s disk "IBM" "2076"

Procedure B

Procedure B requires a kernel rebuild.

Complete the following steps to set a kernel SCSI parameter:

  1. Quiesce the storage.
  2. Place the host system in single-user mode as root.
  3. Edit the /sys/data/cam_data.c file by changing the non-read/write command timeout values in the changeable disk driver timeout section.

    Change from u_long cdisk_to_def = 10; /* 10 seconds */ to u_long cdisk_to_def = 60; /* 60 seconds */

  4. Compile the cam_data.c file by issuing the following command:
    doconfig –c hostname

    Where hostname is the name of the system kernel that can be found in the /sys/conf/ directory.

    The following example shows output from the –c hostname command:

    #doconfig -c "ES47"
    *** KERNEL CONFIGURATION AND BUILD PROCEDURE ***
    
    Saving /sys/conf/ES47 as /sys/conf/ES47.bck
    
    Do you want to edit the configuration file? (y/n) [n]: y
    
    Using ed to edit the configuration file.  Press return when ready,
    or type 'quit' to skip the editing session: quit
    
    
    *** PERFORMING KERNEL BUILD ***
    Working....Wed Mar 22 17:36:19 PST 2006
    
    The new kernel is /sys/ES47/vmunix
    #