Compaq ProLiant 1000 Configuration and Tuning of Sybase System 11 for Microsof - Page 17

Logical Disk

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Page 14 Configuration and Tuning of Sybase System 11 for Microsoft Windows NT on Compaq Servers transaction rate, Sybase SQL Server would perform the checkpoint approximately every 2 minutes. Also if trunc. log on checkpoint is set then a checkpoint will occur every minute Refer to the Disk Subsystem Planning section for more detailed information on how checkpointing can effect disk throughput. Diskperf The diskperf option9 allows you to monitor the disk subsystem activity. It is very useful when monitoring performance of the drive subsystem. If this option is disabled, performance monitor will not be able to monitor low level disk-related activity, such as LogicalDisk and PhysicalDisk counters. Having this option enabled slightly degrades performance. Enable diskperf only when needed, then disable it to get maximum performance. You can enable or disable diskperf using Control Panel/Devices or by issuing the diskperf -y|n command from the system prompt. When using the Control Panel, set diskperf to automatically start at boot time to enable. You must restart your system for the diskperf option to become effective. Disk Performance Monitor Objects and Their Meaning You can monitor LogicalDisk- and PhysicalDisk-related objects, such as Avg. Disk sec/Transfer or Disk Transfers/sec. Monitoring LogicalDisk and PhysicalDisk-related objects requires you to have the diskperf option enabled, which slightly reduces performance. Note that resetting the diskperf option requires you to reboot your machine. Object: Logical Disk Counter: Avg. Disk sec/Read, Avg. Disk sec/Write The Avg. Disk sec/Read and Avg. Disk sec/Write counters monitor the average number of seconds for read or write operations from or to a disk, respectively. Use the following guidelines when optimizing the disk subsystem. Do not have more average disk seconds per read or write operation than the values in the table below. Transaction Log Access (with the Array Accelerator enabled) Database Access (with the Array Accelerator enabled) Avg. Disk sec/Read n/a 20-40msec Avg. Disk sec/Write

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14
Configuration and Tuning of Sybase System 11 for Microsoft Windows NT on Compaq Servers
1996 Compaq Computer Corporation, All Rights Reserved
Doc No 143A/0596
transaction rate, Sybase SQL Server would perform the checkpoint approximately every 2
minutes.
Also if
trunc. log on checkpoint
is set then a checkpoint will occur every minute
Refer to the
Disk Subsystem Planning
section for more detailed information on how
checkpointing can effect disk throughput.
Diskperf
The
diskperf
option
9
allows you to monitor the disk subsystem activity.
It is very useful when
monitoring performance of the drive subsystem.
If this option is disabled, performance monitor
will not be able to monitor low level disk-related activity, such as
LogicalDisk
and
PhysicalDisk
counters.
Having this option enabled slightly degrades performance.
Enable
diskperf
only when needed,
then disable it to get maximum performance.
You can enable or disable
diskperf
using Control Panel/Devices or by issuing the
diskperf -y|n
command from the system prompt.
When using the Control Panel, set
diskperf
to automatically
start at boot time to enable.
You must restart your system for the
diskperf
option to become
effective.
Disk Performance Monitor Objects and Their Meaning
You can monitor
LogicalDisk
- and
PhysicalDisk
-related objects, such as
Avg. Disk sec/Transfer
or
Disk Transfers/sec
.
Monitoring
LogicalDisk
and
PhysicalDisk
-related objects requires you to
have the
diskperf
option enabled, which slightly reduces performance.
Note that resetting the
diskperf
option requires you to reboot your machine.
Object:
Logical Disk
Counter:
Avg. Disk sec/Read, Avg. Disk sec/Write
The
Avg. Disk sec/Read
and
Avg. Disk sec/Write
counters monitor the average number of
seconds for read or write operations from or to a disk, respectively.
Use the following guidelines when optimizing the disk subsystem.
Do not have more average
disk seconds per read or write operation than the values in the table below.
Avg. Disk sec/Read
Avg. Disk sec/Write
Transaction Log Access (with the Array
Accelerator enabled)
n/a
<=10msec
Database Access (with the Array
Accelerator enabled)
20-40msec
<=10msec
If your values are much higher than those suggested in the above table, you may want to increase
the speed of your disk subsystem by adding more drives or using faster drives.
Object:
Logical Disk
Counter:
Disk Transfers/sec
The
Disk Transfers/sec
counter monitors the rate of read and write operations on the disk.
It is
important to realize that if you have a Compaq SMART or SMART-2 SCSI Array controller and
several drives allocated to a logical volume, this counter monitors the total number of disk
9
The
diskperf
option is described in a greater detail in the
Microsoft Windows NT Resource Kit
.