I don’t understand how this is an advantage. Yes, you can swap RAM with the system powered up, but what happens to the information in the module that was removed? Is the OS doing some kind of RAID-like memory allocation? The article wasn’t clear on how this would actually work.
Servers have had memory mirroring as a feature for years. This seems like a cool extension of that technology. It would be an advantage in some systems where scaling out isn’t an option and single node availability needs to be as high as possible.
Apparently, there’s some coordination mechanism, where you tell the OS that you want to remove a certain memory stick, so it moves all the memory onto other RAM sticks (or uses paging to move it to your hard drive). Only then would you actually physically unplug the memory stick.
See, for example: docs.kernel.org/…/memory-hotplug.html
(Mind that this is kernel documentation. If you actually want to do this, there’s probably some CLI program to make it easier.)
I guess, you could see it that way…? The important part is that you don’t have to turn off the whole system. It can continue running without interruption. So, the RAM will be lukewarm when you swap it, but the system will still be hot.
I remember the ‘good old days’ of Sun Fire 10k and similar servers. You could replace entire boards of CPU and RAM and the server would keep on trucking.
I’m curious, does a 3 minutes power down to replace a RAM stick is that much of a deal in enterprise server that they need to invented a whole new technology just for that?
Buddy works in a data center. Ram upgrades on a few racks of servers took him weeks…
Mind you this was with zero downtime. So spin up a server, move the traffic, shut down/swap ram, boot up server, swap traffic back, repeat until you want to cry.
First of all, yeah. In enterprise, 1000 transactions per second can be a requirement. Second, enterprise servers take longer to spool up than 3 minutes.
Many that weren’t based on x86 microcompters could do this: Tandem, I mean, Compaq, I mean HP NonStop machines, Sun Ultra Enterprise as you mentioned, IBM s390 and System-Z, several HPUX systems, I’m sure there’s others.
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