> q xstore > XSTORE= 1024M online= 1024M > XSTORE= 1024M userid= SYSTEM usage= 99% retained= 0M pending= 0M > XSTORE MDC min=0M, max=1024M, usage=12% > XSTORE= 1024M userid= (none) max. attach= 1024M > > Does the above mean that the xstore is being used by the > system already > without me telling the system how/when/where to use it ?
Yes -- you're using 12% of your XSTORE for minidisk cache and I'd suspect the rest is in use as 1st tier paging. If xstore is available, then CP uses it for various things (paging hierarchy, minidisk cache, etc). CP has some default settings (which looks like what you're getting) that aren't really optimal for Linux workloads. You may want to cap MDC or force it to real storage, and I've seen arguments for disabling it entirely. See SET MDC in the docs for twiddling it in and out of XSTORE or turning it off. See your favorite monitoring tool for more details on how CP is using XSTORE. > Do > the users on > the system benefit just by having xstore defined to the system ? Absolutely! If XSTORE is available, CP pages to it first before going to real DASD. This lets you sustain astonishing paging rates -- I think Rob v.d.H. has reported 40,000 pages/sec with good response time, vs 50-60 pps on real disk. Overcommitting RAM for VDISK depends on good VM paging performance, so XSTORE wins big. VM: Autonomic, when Autonomic Wasn't Cool. 8-) ---------------------------------------------------------------------- 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
