The issue with all resources on a 390 is how to share them. Dedicating a limited resource such as exstore to linux that might or might not use it takes that resource away from other guests that would make better use of it.
VDISK on the other hand will end up in xstore or main storage as needed and referenced, and will use significantly less amount of this very limited resource - not only becuase it is paged out, but mostly because the storage is not ever allocated until Linux actually performs a swap. So it is very much like a free lunch. Give linux a huge swap disk that costs you absolute nothing - until linux uses up it's own storage and decides to swap. Makes much more sense to use vdisk from both a performance and economic perspective. >Larry, > >The 2.4.19 source tree still has the code for xpram. My "gut >feel" (since I don't have any direct experience) about this is >that for Linux/390 on VM, it would be better to use the Vdisk, >rather than xpram. My guesss is that the xpram driver will use >the storage, and it's likely to stay "in" whereas the parts of >the Vdisk that aren't referenced for a while will get moved to >disk, assuming sufficient pressure on storage. I would love to >have this reasoning either validated or refuted by someone who >actually _knows_. > >Mark Post > >-----Original Message----- >From: Davis, Lawrence [mailto:[EMAIL PROTECTED]] >Sent: Monday, January 13, 2003 11:08 AM >To: [EMAIL PROTECTED] >Subject: Xstore or V-Disk > > >I was looking at my Linux directories and I have a definition >for XSTORE, but I never modified the LINUX machines to use >XSTORE. I believe the driver use to be XPRAM for the earlier >Linux 2.2 systems. > >on these 2.4.7+ systems > 1. Is XPRAM still available, Or > 2. Should I be using the V-Disk implementation for swap space > >What are your thoughts, and where would these implementations be >documented. > > > \|/ > (. .) >TIA, ___ooO-(_)-Ooo___, Larry Davis "If you can't measure it, I'm Just NOT interested!"(tm) /************************************************************/ Barton Robinson - CBW Internet: [EMAIL PROTECTED] Velocity Software, Inc Mailing Address: 196-D Castro Street P.O. Box 390640 Mountain View, CA 94041 Mountain View, CA 94039-0640 VM Performance Hotline: 650-964-8867 Fax: 650-964-9012 Web Page: WWW.VELOCITY-SOFTWARE.COM /************************************************************/
