Got this from our IBM folks. Thought I'd pass along to the list in case anyone is vulnerable.
Marcy Cortes "This message may contain confidential and/or privileged information. If you are not the addressee or authorized to receive this for the addressee, you must not use, copy, disclose, or take any action based on this message or any information herein. If you have received this message in error, please advise the sender immediately by reply e-mail and delete this message. Thank you for your cooperation." ----- 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.
