50% of volume capacity, according to the documents. I/O rate is a whole different issue.
-----Original Message----- From: The IBM z/VM Operating System [mailto:ib...@listserv.uark.edu] On Behalf Of Gary M. Dennis Sent: Monday, November 02, 2009 10:18 AM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: [IBMVM] Questions - zVM Limits/Hardware Support Extremely useful. The limits document by by Bill Bitner and another by the same author on performance are great resources. If you attempted to configure a VM system with 700 active users each having an average working set of 8GB each what kind of train wreck could that create? All recommendations I see call for keeping the virtual to real ratio <3:1 and I wonder what would happen in this case. I note that VM has been tested to the 1TB real level. If the max number of paging volumes is 255 but you should keep the utilization for of each device at 50% for optimal performance, what does that mean? Are we talking 50% of the potential sustained I/O rate for the device or 50% of physical capacity. If the latter, that pushes the paging cap down to 5.6/7.95. What transmission limits are imposed by ISFC? When would the CTC link max out? Could a very high activity IUCV communications link function well over ISFC? --. .- .-. -.-- Gary Dennis Mantissa Corporation 0 ... living between the zeros... 0 On 10/28/09 4:06 PM, "Alan Altmark" <alan_altm...@us.ibm.com> wrote: > On Wednesday, 10/28/2009 at 04:28 EDT, "Gar over ISFC? M. Dennis" > <gary.den...@mantissa.com> wrote: > >> What is the maximum page space supported by zVM? >> >> What is the supported real storage limit for the hardware and for VM > itself? > > Max page space: > - For ECKD: 11.2 TB > - For FCP: 15.9 TB (emulated FBA on SCSI) > Note that optimal performance requires that you keep utilization of each > device to < 50%. > > Memory limits: > - z/VM supports an LPAR up to 256 GB in size > - The amount of memory on the box and in an LPAR depends on the hw > - Biggest z10 has up to 1.5 TB memory and a the largest LPAR can be 1.0 TB > > You can find these and other z/VM limits in Bill Bitner's "z/VM Limits" > presentation at > http://www.vm.ibm.com/devpages/bitner/presentations/vmlimits.pdf > >> What is the highest total sustained I/O rate you have witnessed on a VM >> system? > > I have heard rumors of a z/VM paging rate of > 200K pages/second on a > robust I/O subsystem, but I don't know if that's what you're referring to. > Guest I/O data rates are a function of access to the CPU and the size of > the I/O operation, so "it depends." > >> I see from an BM presentation that support is available for simulated > guest >> coupling. Does zVM support a real coupler facility for intersystem (VM >> SYSTEMS) communications? > > z/VM does not use and does not allow guest access to the real Coupling > Facility. z/VM's native intersystem comms mechanism is ISFC, based on > CTCs. > > Alan Altmark > z/VM Development > IBM Endicott > --. .- .-. -.-- Gary Dennis Mantissa Corporation 0 ... living between the zeros... 0 -------------------------------------------------------------------------- This message w/attachments (message) may be privileged, confidential or proprietary, and if you are not an intended recipient, please notify the sender, do not use or share it and delete it. The information contained in this e-mail was obtained from sources believed to be reliable; however, the accuracy or completeness of this information is not guaranteed. Unless specifically indicated, this message is not an offer to sell or a solicitation of any investment products or other financial product or service, an official confirmation of any transaction, or an official statement of Merrill Lynch. Subject to applicable law, Merrill Lynch may monitor, review and retain e-communications (EC) traveling through its networks/systems. The laws of the country of each sender/recipient may impact the handling of EC, and EC may be archived, supervised and produced in countries other than the country in which you are located. This message cannot be guaran teed to be secure or error-free. References to "Merrill Lynch" are references to any company in the Merrill Lynch & Co., Inc. group of companies, which are wholly-owned by Bank of America Corporation. Securities and Insurance Products: * Are Not FDIC Insured * Are Not Bank Guaranteed * May Lose Value * Are Not a Bank Deposit * Are Not a Condition to Any Banking Service or Activity * Are Not Insured by Any Federal Government Agency. Past performance is no guarantee of future results. Attachments that are part of this E-communication may have additional important disclosures and disclaimers, which you should read. This message is subject to terms available at the following link: http://www.ml.com/e-communications_terms/. By messaging with Merrill Lynch you consent to the foregoing. --------------------------------------------------------------------------
