On Thu, Jun 18, 2009 at 6:38 AM, Bernie VK2KAD<[email protected]> wrote:
> For example, I know that Cognos for example is capable of running on zLinux > - but when I look at it's workload profile on existing mid-range hardware if > appears that it wouldn't be a very sociable guest. From practically idle > to 100% busy for 1-2 hours or more says this guy doesn't like to share his > toys and thus wouldn't be a very good candidate - or am I wrong?? Important question is how often it has this requirement and what other workload you have. If it's once a day and you have other workload fill in the remaining 22-23 hrs of capacity, it may be a great fit. On the fine level we talk about interleaving workload that has a mix of resource requirements so the system can run a few workloads at the same time without delaying either of them significantly (one uses the CPU while the other waits for I/O to complete). When your Cognos workload is CPU constrained, it would only combine well with workload that is for example I/O constrained. On the coarse level you talk about virtual server utilization. When each server is only busy during one hour of the day, you can fit 20 of them on the machine. Queueing theory shows that the more servers and resources you have, the better are your odds that not everyone will have their share at the same time. You need to collect usage data from the servers and applications that you want to consolidate, and analyze that to see if it fits. And probably do a proof of concept to compare your apples and oranges (a CPU second on Intel is not the same as a CPU second on System z). In the early days of Linux on z/VM, we were using very slow CPUs so that 1-2 hrs on the other hardware meant 10-20 hrs of CPU on S/390. That made it very hard to compete and we told people to stay away from CPU-intensive workload. Today mainframe CPUs are as fast as the rest. One reason this logic does not apply equally to other platforms is that the mainframe technology for sharing is more mature. -- Rob van der Heij Velocity Software http://www.velocitysoftware.com/ ---------------------------------------------------------------------- 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
