Am Freitag, 8. August 2008 schrieb Mark Perry: > Pieter Harder wrote: > > Hi list, > > > > I am starting to think about the possibilities 2GB above the bar DCSS in z/VM 5.4 will provide for replacing large Vdisk swap. But I can't find any usable documentation on how to do swap to DCSS. The basics are documented on dw and I can probably manage, but when anyone has been there and done that can you please post some pointers and save us all the trouble of finding out again. Performance information is quite welcome as well. > > > Hi Pieter, > DCSS is good for sharing code (or constant data) between Guests. Swap > data is unique to only one Guest. What do you hope to gain over > a/multiple VDISK - size? performance?
In theory swap over dcss can have lower overhead than vdisk, if z/VM has enough memory to hold the dcss in main storage. For vdisks every I/O operatin is an SIE intercept (either diag or channel program parsing). I/O to a fully memory resident dcss I/O is memory access only and does not cause any sie exit. I have no idea about the performance, if z/VM has to do a lot of paging and the dcss is not resident. Christian ---------------------------------------------------------------------- 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
