Kernel / Environment Variables (System Resources)
It would be advisable to check the OS kernel and environment variables to make sure that all correct settings are applied as explained in the Installation manual and in the pre_install.sh script prior to checking other aspects of the system.
Disk I/O Performance
ALTIBASE HDB's performance rely on the performance of the hardware. Therefore, it is neccessary to check the performance of Disk I/O.
You can use following command to see the performance of a disk (this will create a 1GB file full of 0’s.)
It simply displays the time it takes to copy a file.
Direct I/O Use
ALTIBASE HDB provides two disk I/O methods related to database files:
• Direct I/O
• Buffered I/O
One advantage of Direct I/O is that it reduces CPU resource consumption during occurance of Disk I/O. On the other hand, since the Buffered I/O uses techniques of read-ahead and asynchronous write, it may not access disk every time when an disk I/O is required. It means that the Buffered I/O is faster than the Direct I/O. However the Buffered I/O consumes a higher level of CPU resources when compared to the Direct I/O.
There are three properties that users have to look at to use the Direct I/O in ALTIBASE HDB
- LOG_IO_TYPE
- DATABASE_IO_TYPE
- DIRECT_IO_ENABLED
To use Direct I/O, you have to mount disk with following options.
OS |
File System |
mount option |
---|---|---|
Solaris |
UFS |
none |
HP-UX |
Veritas VxFS |
mount with convosync=direct |
Solaris |
Veritas VxFS |
mount with convosync=direct |
AIX |
Veritas VxFS |
mount with convosync=direct |
AIX |
JFS |
mount with use -o dio |
Windows NT/2000 |
All |
none |
Tru64 Unix |
AdvFS |
none |
Linux(2.4 > k) |
All |
none |
In systems where direct I/O cannot be used, ALTIBASE HDB will use Buffered I/O regardless of the property settings.
vmstat utility
The vmstat is a system utility that is available in most Unix-based operating systems, and it is used to assess the state of the system in conjunction with memory and CPU. Some OSs support their own proprietary utilities such as "nmon analyzer". The resources controlled by OS is closely related to the performance problems. Therefore, important thing is to gather this information effectively. So here is an example way you can do this:
Please refer to the man page in each OS for further details. This shell above is applicable to AIX OS.
iostat utility
The iostat which is a system tool to assess the I/O state of the system. It is similar to vmstat. I/O flow is also coupled with the performance on the system. Here is an example shell using of iostat:
Please refer to the man page in each OS for further detail. This shell above is applicable to AIX OS.