Mark Post wrote: <SNIP/>
Why do you have 1GB of swap defined for each guest? That sounds far too high for most uses. Are you following the rule of thumb to use "twice the amount of physical RAM?" If so, you shouldn't be doing that. It's not even valid in the midrange world any more, although a lot of people supporting those kinds of systems haven't gotten the memo yet. In the last major Intel deployment I was involved with, the consultants from the third-party intermediary insisted that we do that for systems with 8GB, 16GB, etc., even though the amount of swap space actually being used on the systems was *zero*. "This is what Oracle recommends, so we want you to do that." I fought it, but the account manager caved, finally.
Your comments regarding "3rd party" recommendations are spot-on. SAP in SAP Note 171356 explicitly states: "Swap space While the Linux distribution is being installed, create partitions of the type "swap" when you organize the hard disk(s). Recommended total size: Twice the main memory structure (2 x RAM)." Due to increased storage requirements for JVM (dual stack SAP, garbage collection issues etc.), the storage per Guest could be (at least) 3GB with therefore 6GB of swap.
Squeeze your guests down as much as possible, and see how much swap really gets used. (Remember, VDISK can support a _lot_ of paging I/O with no performance impact.) Reduce your swap sizes to cover that, plus as much "insurance" as you think you might need.
I will be experimenting over the next few months (with SLES10) to see what "really" works for SAP on zLinux under z/VM using VDISK..... Mark ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
