Brian Kernighan on the origins of Unix [LWN.net]

Brian Kernighan on the origins of Unix

Posted Jan 21, 2022 12:01 UTC (Fri) by Cyberax (✭ supporter ✭, #52523)
In reply to: Brian Kernighan on the origins of Unix by sfeam
Parent article: Brian Kernighan on the origins of Unix

People tried that with Linux (famous Beowulf clusters!) but this really doesn't buy you a lot. Why would you migrate jobs between hosts in the first place?

You can do full machine migration easily either via VM checkpoint/restore or via CRIU, and this is useful in virtualization scenarios. You can also do high-availability via Xen where the same code runs on two computers at once, in case one of them goes down.

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Brian Kernighan on the origins of Unix

Posted Jan 21, 2022 13:58 UTC (Fri) by malmedal (subscriber, #56172) [Link] (5 responses)

I don't think Beowulf clusters had that capability. You could schedule your job in any cluster-member, but not move them. Similarly with VMS, you could maintain the illusion of 100% uptime of a specially written application even while replacing all hardware.(admittedly I've only used VMS on VAX, maybe later versions could actually move jobs).

MOSIX however, could move arbitrary processes between cluster machines.

Another option is Condor, which uses CRIU to move simple processes.

Beowulf

Posted Jan 21, 2022 14:01 UTC (Fri) by corbet (editor, #1) [Link]

Yeah...Beowulf clusters still exist, they are just called "data centers" now...

Brian Kernighan on the origins of Unix

Posted Jan 21, 2022 18:14 UTC (Fri) by Cyberax (✭ supporter ✭, #52523) [Link] (3 responses)

Yes, they did. You could migrate processes between nodes: https://web.archive.org/web/20031002104248/http://www.ope... with some measure of automatic load balancing.

Brian Kernighan on the origins of Unix

Posted Jan 21, 2022 18:36 UTC (Fri) by malmedal (subscriber, #56172) [Link] (2 responses)

I believe I said Beowulf couldn't but MOSIX could migrate processes, they are different things.

Brian Kernighan on the origins of Unix

Posted Jan 21, 2022 18:38 UTC (Fri) by Cyberax (✭ supporter ✭, #52523) [Link] (1 responses)

Sorry, I'm a writer, not a reader. 🤦

Yes, of course you're correct. I used a Beowulf cluster with MOSIX back in the day, so that's why I'm confusing two of them.

Brian Kernighan on the origins of Unix

Posted Jan 22, 2022 13:03 UTC (Sat) by malmedal (subscriber, #56172) [Link]

My own memory also rather lacking at this point, but I think the deal-breaker for me was that the migrated process would die if the node it originally ran on rebooted.

Did MOSIX ever fix that issue?