[LMB] Server move imminent

Zan Lynx zlynx at acm.org
Mon May 3 23:27:57 BST 2021


On 5/3/21 3:39 PM, Matija Grabnar via Lois-Bujold wrote:
> Thank you for caring for this list, and for moving us to new server.

Yes, thanks!

> Moving things without downtime is an art.

I have done similar things in the past, and I can say it is a lot easier 
with something like a mailing list where items are only ever added and 
never removed. And, there probably isn't a database involved.

Sync the files and test. Sync the files again. Shut down the old 
service, sync the files and bring up the new one! And test.

If you're doing a 20 TB PostgreSQL database set it gets a lot messier! 
(I would have to read up the details again but it involved block 
snapshots, remote snapshot sync, and PostgreSQL WAL (Write Ahead Log) 
files.)

One neat trick I saw done with DNS was, as long as the owner controlled 
both the old and new IP addresses, the old IP was set to proxy 
connections to the old IP, and left that way until the DNS managed to 
update everywhere. Truly zero downtime.

-- 
                 Knowledge is Power -- Power Corrupts
                         Study Hard -- Be Evil



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