On Tue, 2004-03-02 at 22:32, Adam Thornton wrote:

> mkswap /dev/dcssblk/dcssname
> swapon /dev/dcssblk/dcssname

No no, not like that. The cute thing about swapping into an EW DCSS is
that you can save the DCSS such that it is a pre-initialized swap device
and don't have to mkswap on it. So you could include it in fstab. Too
bad you still need to tell the driver to attach the segment. I suppose
it could be helpful if the driver would read a config file when it
starts.

Obviously being able to attach extra RW memory requires authorization
because it would let you get a larger share of real memory than the
virtual machine size was set up for. If you allow everyone to have one
copy of the swap DCSS you can make it EW. If you want only some people
to use it you can make it restricted and give some a NAMESAVE statement.

I expect swapping in DCSS to be slightly more efficient than in VDISK,
although both build on the same z/VM infrastructure. The difference is
that you can swap in DCSS under SIE and don't break out to CP to have it
do the work for you. But I don't have any numbers right now beyond the
work we did for the ISP/ASP redbook where the appendix has such a DCSS
driver.

Rob

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