Enabling Command Tag Queuing - Hitachi Universal Storage Platform V Configuration Manual

Enabling Command Tag Queuing

Command tag queuing (CTQ) must be enabled to optimize the performance of
the USP V devices. Since CTQ is disabled by default in IRIX systems, you need
to enable it and set the queue depth for each USP V logical device using the fx
utility.
Table 3-1
Parameter
Queue depth per LU
Queue depth per port
Note: You can adjust the queue depth for the USP V devices later as needed
(within the specified range) to optimize the I/O performance of the USP V
devices. If I/O response time will be long, you must adjust queue depth
parameter. You can check the response time using the sar command (see
Figure 3-4) and set queue depth within 10 seconds.
sgi 1# sar –d 1 10
IRIX64 sgi 6.5-ALPHA-1276737220 09080737 IP27
11:01:02
11:01:03
Figure 3-4
To enable CTQ and set the queue depth for the USP V devices (see
5):
1. Start the fx disk utility and select the desired device to configure.
2. Once the device is selected and the fx> prompt reappears, enter
/label/set/para to set the command tag queuing and queue depth
options.
3. When prompted, enter enable to enable CTQ and enter the desired CTQ
depth (e.g., 32).
4. When prompted, enter yes to modify the drive parameters as specified.
5. Exit the fx utility and enter yes to write out (save) the changes to the
drive parameters.
6. Repeat steps 1 through 5 for each new USP V disk device.
3-6
Hitachi Universal Storage Platform V/VM Configuration Guide for SGI
Table 3-1 lists the queue depth requirements for the USP V devices.
Queue Depth Requirements for the USP V Devices
≤ 32
≤ 1024
device %busy avque r+w/s blks/s
dks0d1 0 0.0
dks0d6 0 0.0
dks14d0 100 4.0
dks14d0l1 100 5.5
dks14d0l2 100 4.5
dks14d0l3 100 5.2
dks14d0l4 100 5.7
dks14d0l5 100 5.0
Checking the I/O Response Time Using the Sar Command
Configuring the New Disk Devices
Required Value
10/17/00
w/s wblks/s avwait avserv
0.0 0 0.0
0.0 0 0.0
2.0 133 2.0
3.9 500 1.0
2.0 250 0.0
3.9 2219 1.0
2.9 252 1.0
2.0 250 0.0
Input sar command.
0 0.0 0.0 time (msec)
0 0.0 0.0
133 1745.0 290.0
125 1117.5 285.0
0 955.0 510.0
2 1735.0 255.0
2 963.3 276.7
0 1585.0 370.0
Figure 3-
® ®
IRIX Host Attachment
Response