Re: Questions - zVM Limits/Hardware Support
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. --
Re: z/LInux, LVM, and minor disasters.
Define a LOT. We have Linux guests with over 100 DASD volumes in LVM, and I've run Linux in LPAR with close to 1000 devices visible, and haven't had any problem I couldn't explain. One of the difficulties is, it can be hard to determine whether or not a device is missing when there are that many. Examining the console log from boot (dmesg) can be useful, plus looking at q v dasd and comparing against lsdasd under Linux. Keeping the device numbers consistent and sequential makes this much easier, and as the previous poster said, LVM doesn't care where the volumes are, as long as it can collect them all. Occasionally we have seen LVM get corrupted, but that was almost always traceable back to some human error. -Original Message- From: The IBM z/VM Operating System [mailto:ib...@listserv.uark.edu] On Behalf Of Paul Raulerson Sent: Friday, October 30, 2009 6:16 AM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: [IBMVM] z/LInux, LVM, and minor disasters. Hi Mark - I would have agreed 100% with you up until a few days ago. I am still not sure it was LVMs fault. There were a LOT of DASD volumes attached to this instance, and I think I may have blown some limit somewhere. Part of the reason there were multiple LVMs is that I had a lot of 3390-3's around, and LVM, at least at one time, seemed to have trouble with creating volumes that were much larger than 100gigs using 3390-3s. Fell into a historical habit I suppose. It worries me enough, and the fact I can duplicate it, makes me worried enough to not want to use LVMs for a while. I was kinda hoping someone else had ran into this, but perhaps it is more likely I am just doing something wrong -Paul On Oct 30, 2009, at 1:27 AM, Mark Post wrote: On 10/30/2009 at 1:23 AM, Paul Raulerson p...@raulersons.com wrote: -snip- Has anyone else ran into this? Not without some error messages and the like to go on. LVM doesn't care about device names, or DASD address ordering, etc. All it cares about is if it can find the UUIDs it expects for all its PVs. Those are written on the disk volumes when pvcreate and vgextend is done. If it can't find all those UUIDs, then it will throw a fit. Usually that means that a PV was added to the VG, and that volume was not available at the next reboot. Most often that's the result of not re-running mkinitrd and zipl. (YaST will do that for you automatically if you use it, otherwise you have to remember to do it. Not sure if Red Hat has a similar mechanism to keep things in synch.) Mark Post -- 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. --
Re: Questions - zVM Limits/Hardware Support
Funny, there was a session on just this stuff at the z Expo a few weeks ago, and I had the handout handy. Max paging volumes: 255 (number of CP volume slots) Max real storage supported: 256GB, however higher has been tested. I've heard reports of VM being driven with something like 47,000 Linux guests, but I don't believe they were doing much. We have over 100 on our busiest system, and it's not heavily loaded. Highest sustained I/O rate would depend on architecture. FICON can handle much higher rates than older architectures, and under the right conditions, I've managed to saturate a 2GB. FCP channel. Best I got out of a single FICON channel with no contention was 60MB/sec. This will vary a lot with different hardware configurations. Sorry, no idea about the coupler stuff. -Original Message- From: The IBM z/VM Operating System [mailto:ib...@listserv.uark.edu] On Behalf Of Gary M. Dennis Sent: Wednesday, October 28, 2009 3:31 PM To: IBMVM@LISTSERV.UARK.EDU Subject: [IBMVM] Questions - zVM Limits/Hardware Support Questions... What is the maximum page space supported by zVM? What is the supported real storage limit for the hardware and for VM itself? Does anyone have experience with a zVM system having over 500 non-CMS guest systems? What is the highest total sustained I/O rate you have witnessed on a VM system? 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? Thanks --. .- .-. -.-- Gary Dennis Mantissa Corporation -- 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. --
