Thanks, Marcy. This does indeed sound like a critical issue....
Marcy Cortes wrote:
Got this from our IBM folks. Thought I'd pass along to the list in case
anyone is vulnerable.
Marcy Cortes
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----- Forwarded by Cathy Cramer/Des Moines/IBM on 11/05/07 11:37 AM
-----
This is urgent information for customers running Linux guest systems
under z/VM 5.3 with FCP attached storage. Affected Linux distributions
are SLES10 and RHEL5. When the guest system configuration contains
multiple virtual CPUs and the guest memory exceeds 2GB, there is a
severe issue, which can cause data corruption and/or system outages.
Customers are urgently advised - as a workaround for this issue - to
disable the V=V queue support (QIOASSIST) functions for all FCP adapters
attached to affected guests by specifying the NOQIOASSIST parameter in
the device definition statement or when attaching the FCP adapter to the
guest. It is not sufficient to set QIOASSIST=OFF for the guest or host
system by issueing the SET QIOASSIST OFF command. Note, that enabling
this workaround, will significantly increase CPU consumption in the host
system.
Customers running z/VM versions before z/VM 5.3, or Linux distributions
SLES8, SLES9 and RHEL4, as well as guest systems with a memory size
smaller than 2GB or only one virtual CPU are not affected by this issue.
Also OSA Networking is not affected by the issue.
z/VM APARS VM64287 and VM64297 are related to this problem, but do not
finally resolve the issue. For further information on resolution of this
issue, please watch QIOAssist Requirement Webpage
(http://www.vm.ibm.com/perf/aip.html) which currently documents the
z/VM, Linux and CP Millicode service levels required to run QIOAssist.
z/VM APAR 64306 is open for that problem.
--
DJ
V/Soft
