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For your disk bottleneck question, there are lot's of things you can do and lot's of opinions and guides on what to look for. First of all, here's some good info to read:
It is simple, I know, but I always start out with the good old sar command. sar 1 100
This gives you a check of the system every 1 second for 100 seconds. This is the easiest and quickest way to get a good look at your system.
If your sar output shows your %WIO to consistently be above 40%, you should start looking further with the iostat and check out specific disks. When you start seeing %WIO hitting at 70-80 percent, you will notice a difference in performance. In the 90's and you can really tell there's a problem.
Some misc thoughts on disk I/O:
1. Remember, high wait I/O can be from high paging on memory. So what you think is a disk bottleneck can actually be coming from a memory problem.
2. Doing large FTPs, TARs, RMs, and such during your normal business day (when users are active) is not wise as they are I/O intensive.
3. Look into disk reorging. Especially if you have a high I/O application, either high reads and/or high writes. Check out the placement of your filesytems on your disks. Don't group the filesytems most used together on the same disks.
4. Increase your amount of JFS logs and spread them out.
Remember, amateurs built the Ark, professionals built the Titanic.
It is simple, I know, but I always start out with the good old sar command. sar 1 100
This gives you a check of the system every 1 second for 100 seconds. This is the easiest and quickest way to get a good look at your system.
If your sar output shows your %WIO to consistently be above 40%, you should start looking further with the iostat and check out specific disks. When you start seeing %WIO hitting at 70-80 percent, you will notice a difference in performance. In the 90's and you can really tell there's a problem.
Some misc thoughts on disk I/O:
1. Remember, high wait I/O can be from high paging on memory. So what you think is a disk bottleneck can actually be coming from a memory problem.
2. Doing large FTPs, TARs, RMs, and such during your normal business day (when users are active) is not wise as they are I/O intensive.
3. Look into disk reorging. Especially if you have a high I/O application, either high reads and/or high writes. Check out the placement of your filesytems on your disks. Don't group the filesytems most used together on the same disks.
4. Increase your amount of JFS logs and spread them out.
Remember, amateurs built the Ark, professionals built the Titanic.
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Remember, amateurs built the Ark, professionals built the Titanic.
Remember, amateurs built the Ark, professionals built the Titanic.
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