I wanted to chime in on this discussion, but it has taken me a day or two to both find the time to write this and get everything said the way that I want it said. We've been running z/Linux here at UConn from pretty much the beginning. We had (I'll explain "had" in a moment) about 45 (prod/test) servers running on a z/890 up until about 6 months ago when we purchased our new z/10 BC. The 45 servers that ran on our z890 were things like LDAP, CAS, FTP, Listserv, WEB servers, Proxy, DNS, SAMBA, etc., all "reasonably" medium to small (2G-500M memory) servers. At times, we definitely maxed out our z/890, but this was usually due to an errant process running out of control or a large email delivery on Listserv. For the most part we hovered between 45-65% CPU with a 2.1:1 virtual:real memory ratio with 18G central and 2G expanded storage on 1 IFL. We purchased the new z/10 hoping to migrate our 9672, z/OS system and z/890, z/VM and z/Linux LPAR's to one box. We've completed the migration of our z/890 to a z/10 BC, so we're currently running z/VM 5.4 on a GP and z/VM 6.1 with 36 prod/test z/Linux servers running on 1 IFL with 24G central and 3G expanded storage. Our current virtual:real memory ratio is 0.8:1, we run somewhere around 20-30% CPU and we "never" peak any more. The "your mileage may vary" statement should be included here, but I just wanted to show you what we had done.
Now on to the "bad" part of this conversation, where I explain the reason why we have reduced the number of z/Linux servers from 45 to 36 (remember when I said "I'll explain "had" in a moment"). The reason for the reduction is because we also started buying Blade servers, running VMWare at the same time that we purchased our new z/10 and many of our z/Linux servers have either moved or are planned to be moved to this environment instead. So you're asking, why would you buy a new z/10 just to migrate all of your z/Linux servers somewhere else? Our initial decision to get the z/10 was to move our z/OS system, the IFL (and z/Linux) was just an added bonus, "at least for me"! I could get into why we've decided to migrate off of z/Linux to Blades/VMWare/Linux, but it's all of the same old story (application certification, application inoperability with anything other than Sun Java, and the ole classic, "it's not Intel"). Anyway, the main purpose of this response was to show you how many servers "can" run, effectively, on 1 IFL for your comparison... Mark Wiggins University of Connecticut -----Original Message----- From: John Cousins [mailto:[email protected]] Sent: Monday, December 06, 2010 12:08 PM Subject: How many virtual servers per IFL? Here we go again! Without success, we've been trying to get the IT department here to adopt z/Linux since 2003! Our zVM licence has been recently cancelled, and I have just had a request from our Enterprise Architects for some costing for z/Linux as they need to compare server virtualisation costs with VMware! One problem of trying to get a cost per virtual server was always trying to estimate how many servers an IFL will support. We had a 13 SuSe servers defined in a z800 IFL but as they were hardly used we couldn't measure a thing! So are there any rules of thumb out there on how many production virtual servers would run on a Z10 IFL? Obviously it will depend on server utilisation, guess that will need to be estimated as well? Another question is where do the bulk of the savings come from? From my investigations over the years other success stories suggest most savings come from software licensing, e.g Oracle, Tivoli etc. but also from networking infra-structure by the use of virtual switches. Are there any other areas that provide benefits? Any ideas or constructive suggestions would be gratefully received! Best regards John John Cousins Senior IT Officer Central Support Services ICT Division Bristol City Council Romney House Romney Avenue PO Box 1380 Bristol BS7 9TB Tel : 0117 922 4705 Fax: 0117 922 3983 e-mail: [email protected] ______________________________________________________________________ 'Do it online' with our growing range of online services - http://www.bristol.gov.uk/services Sign-up for our email bulletin giving news, have-your-say and event information at: http://www.bristol.gov.uk/newsdirect View webcasts of Council meetings at http://www.bristol.gov.uk/webcast Bristol is the UK's first Cycling City. Visit www.betterbybike.info to join thousands of others getting around by bike. ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
