Yes, the updates are visible to all users of the DCSS.
See Usage Note 3 from HELP CP DEFSEG:
Pages either defined as, or defaulted to, the no data saved attribute
are initialized to a page of zeros when first referred to. If the pages
are in an exclusive segment, changes are seen only by the one user. If
the pages are in a shared segment, any changes previously made by any
sharing user (if allowed) are visible to all other users sharing that
same page.
I have an inhouse written application that uses a SN DCSS to share data
with multiple users. The DCSS is updated by a service VM and read by
general users. An internal "locking" mechanism causes readers to wait
when the DCSS is being updated, (DCSS is updated about every 15 seconds).
--
Dale R. Smith
"I never make stupid mistakes. Only very, very clever ones."
- Doctor Who
On Mon, 12 Apr 2010 15:28:50 -0500, Leland Lucius <[email protected]>
wrote:
>If I were to define a DCSS as type SN and populate it with a filesystem
full
>of data, how is z/VM going to share it among several Linux guests?
>
>I'm assuming that the pages of the DCSS are shared among the guests such
>that there's really only one page actually in memory and that every gues
t
is
>mapped to that page right? So, what about the pages that are written
to? I
>understand that for type SW, every guest would see the updated page and
>there's still only 1 page in memory.
>
>But what happens for type SN? If a guest writes to a page, are the
updates
>visible to the other guests?
>
>I know, I know...I can just test it myself, but it would be good to hear
it
>from the ppl that know for sure.
>
>Thanks,
>
>Leland
>
