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>Yeah, but let's be clear here: "rolling upgrades" means a completely >redundant set of servers... No, no no, that's exactly not what it means. Let's say I have 2 servers running my site. I can take one offline, leaving 1 server running my site, upgrade that one and then put it back online. Then I can take the other server offline and upgrade it and put it back online. If I have only 1 server, then yes, I need a completely redundant server, but once I have more than one I can just use part of the cluster for the upgrade. >I'd love to see the offsite DR system that can handle >20 Windows servers--or 120... and how much that costs. We use one in Hawthorne, NY. We've got a dozen or so servers up there and that's not a drop in the bucket for that data center. Costs a couple grand a month -- peanuts. >3. You can partition your machine and use a small partition as the >"backup" box as in option 1. Um, sort of. Yes, you can do an OS upgrade on partition 1 while running partition 2. But what about hardware upgrades, or upgrades to the service processor? >the vast majority of software upgrades for the iSeries can be >loaded while the machine is running, and only a subset of them >require so much as an IPL No argument -- and the same is true of windows. I'm speaking of the upgrades that do require downtime. How long does it take to upgrade the OS? Between full save (twice?), OS load, ptf load, validation and full save, that's usually a full weekend event -- often a long-weekend. That really puts a dent in the five-nines concept. >Personally, I doubt there are a lot of truly 24/7 sites. I'll agree with that! >POINT: iSeries upgrades are less frequent, less intrusive and require >less overall downtime than Windows upgrades. On a single piece of hardware, perhaps -- and I'm not convinced about that. However, that misses the point. Users no longer care if the computer is up or down, they care if the application is up or down. Multiple pieces of hardware will _always_ provide better uptime than a single piece. -Walden PS. It's the long weekend. How many people are doing OS upgrades this weekend? ------------ Walden H Leverich III Tech Software (516) 627-3800 x11 WaldenL@xxxxxxxxxxxxxxx http://www.TechSoftInc.com Quiquid latine dictum sit altum viditur. (Whatever is said in Latin seems profound.) -----Original Message----- From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Joe Pluta Sent: Friday, September 02, 2005 3:15 PM To: 'Midrange Systems Technical Discussion' Subject: RE: iSeries TCO v NT server farm Yeah, but let's be clear here: "rolling upgrades" means a completely redundant set of servers. You can't have, say, five servers and then one that backs up the other five. So the concept of redundancy on a server farm is no different than redundancy on an iSeries... except that with an iSeries you have many more options: 1. You can have a smaller backup box dedicated only to mission critical functions that is much cheaper than your primary box, and is used during outages. My guess is that maintaining such a system in a Windows environment is a bit more difficult. 2. You can have an offsite box that you lease from a DR firm for major outages. With creative planning, you can conceivably use this box for planned outages. I'd love to see the offsite DR system that can handle 20 Windows servers--or 120... and how much that costs. 3. You can partition your machine and use a small partition as the "backup" box as in option 1. This is less amenable to unplanned outages, but works very well for planned maintenance and can be a cheaper option (although with the price of a 500CPW machine down around $10K, it's harder for me to justify the cost and complexity of partitioning). POINT: A single machine is easier to maintain, upgrade, manage and failover than a cluster. A cluster provides no more failover capability than a single machine; you still need redundant machines, connections, etc. in order to successfully provide HA. Also, I don't know as much about Windows, Walden, but the vast majority of software upgrades for the iSeries can be loaded while the machine is running, and only a subset of them require so much as an IPL, which is indeed a wee-hours planned outage thing. Personally, I doubt there are a lot of truly 24/7 sites. Frankly, I see "system unavailable" messages on even supposedly 24/7 sites ("The electronic banking system is unavailable for planned maintenance") with far more regularity than I have ever seen an iSeries IPLed. POINT: iSeries upgrades are less frequent, less intrusive and require less overall downtime than Windows upgrades. Joe > From: Walden H. Leverich > > >Most importantly, business is 24x7. This application, once live, can > >probably withstand short downtimes in the wee hours each day, but not > >much more. > > Rich, > > Sure, the iSeries is stable, but it does go down. Sometimes (granted > rarely) in an unplanned way, but other times in a planned way, be it for > hardware upgrades, OS upgrades, full backups, PTF installs, etc. And > these planned downtimes are often more than "short downtimes in the wee > hours each day." > > So, if you need to be up nearly 24x7, are you planning on buying two > iSeries? > > Part of the advantage of a cluster is so the application can survive > "unplanned" outages, but the other advantage is the ability to do > rolling upgrades where you take a part of the cluster offline and > upgrade it, but the application continues to run on the other parts. > > Just something to add into the mix. > > -Walden
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