VERITAS File SystemÖ 3.5 (HP OnlineJFS/JFS3.5) AdministratorÆs Guide (December 2002)

Chapter 9
VERITAS QuickLog
QuickLog Administration and Troubleshooting
92
QuickLog Administration and Troubleshooting
This section discusses QuickLog functionality important to a system administrator responsible for
implementing and tuning QuickLog.
QuickLog Load Balancing
QuickLog can perform load balancing when two or more physical volumes are attached to a QuickLog device.
QuickLog supports from one to four QuickLog volumes attached to each of the 63 QuickLog devices.
QuickLog monitors the average response time for each volume attached to a QuickLog device. If some
volume(s) are responding faster than others, QuickLog diverts more of the log writes to those volumes,
decreasing the overall response time for the device.
You can add a QuickLog volume to a particular QuickLog device with no more than three QuickLog volumes
attached to grow the device’s capacity. Similarly, you can remove a QuickLog volume from a QuickLog device
with at least one other QuickLog volume attached to shrink the device. Growing or shrinking a QuickLog
device does not interrupt file systems logged by QuickLog.
To shrink a QuickLog device that has more than one attached QuickLog volume, detach a QuickLog volume
from the QuickLog device by using qlogdetach:
# qlogdetach vxlog[1-31] qlog_volume
Alternatively, if you want to remove the QuickLog volume that you are detaching from the QuickLog device
your are shrinking, use qlogrm:
# qlogrm qlog_volume
Before the QuickLog volume is detached, qlogdetach flushes all valid log blocks back to the corresponding
VxFS logs. The remaining attached QuickLog volumes take up the load released by the removed volume.
To grow a QuickLog device that has three or fewer attached QuickLog volumes, create and attach a QuickLog
volume to the QuickLog device by using qlogmk:
# qlogmk -g diskgroup vxlog[1-31] qlog_volume
If the QuickLog volume that you want to attach already exists, attach the volume by using qlogattach:
# qlogattach vxlog[1-31] qlog_volume
The newly attached QuickLog volume begins receiving VxFS log writes being sent to the QuickLog device,
easing the load on the existing QuickLog device volumes.
QuickLog Statistics
QuickLog maintains statistics about the QuickLog devices, QuickLog volumes and the VxFS file systems
logged by QuickLog. The statistics include:
• The number of read and write I/O operations per second
• The average number of read and write I/O operations per second
• The number of bytes per second for read and write I/O operations
• The average number of bytes per second for read and write I/O operations
• The average service time for read and write I/O operations
See the qlogstat (1M) online manual page for details.