RE: KAIO in AIX

Below are updated recommendations from an AIX 4.3 manual. http://www.rs6000.ibm.com/doc_link/en_US/a_doc_lib/aixprggd/kernextc/async_i o_subsys.htm How many AIO servers do I need? Here are some suggested rules of thumb for determining what value to set MAXIMUM number of servers to: The first rule of thumb suggests that you limit the MAXIMUM number of servers to a number equal to ten times the number of disks that are to be used concurrently, but not more than 80. The MINIMUM number of servers should be set to half of this maximum number. Another rule of thumb is to set the MAXIMUM number of servers to 80 and leave the MINIMUM number of servers set to the default of 1 and reboot. Monitor the number of additional servers started throughout the course of normal workload. After a 24-hour period of normal activity, set the MAXIMUM number of servers to: (The number of currently running aios + 10), and set the MINIMUM number of servers to: (The number of currently running aios - 10). In some environments you may see more than 80 aios KPROCs running. If so, consider this rule of thumb: A third suggestion is to take statistics using vmstat -s before any high I/O activity begins, and again at the end. Check the field iodone. From this you can determine how many physical I/Os are being handled in a given wall clock period. Then increase the MAXIMUM number of servers and see if you can get more iodones in the same time period. -----Original Message----- From: chris_burton@blue-skies.net To: informix-list@iiug.org Sent: 3/18/00 2:38 PM Subject: Re: KAIO in AIX On Fri, 17 Mar 2000 17:14:11 -0800, "Bernstein, Rick" <rbernste@alarismed.com> wrote: This does seem high. I am assuming that you are only talking about the number of disks associated with the database. Any variances for RAID? Thanks Chris > >Andre, > >I am not sure what you mean by "more KAIO to the engine". >However, IBM recommends that the following KAIO parameters be set >based on your number of disks. > MINIMUM number of servers = 5 * (# of disks) > MAXIMUM number of servers = 10 * (# of disks) > >These values are significantly higher than the default settings. >They can be viewed and changed in the "smitty chgaio" panel. > >Rick > >-----Original Message----- >From: Andre Ngo >To: informix-list@iiug.org >Sent: 3/17/00 3:51 PM >Subject: KAIO in AIX > >Hi all!!! >I came to a deadlock tying to figure this one out. >Is there a way to add more KAIO to the engine? >We are currently using Informix Dynamic Server 7.31.UC3 installed on in >AIX 4.3. >Thanks! >Andre Ngo > > >Sent via Deja.com http://www.deja.com/ >Before you buy.