2018-05-08 1:46 GMT+02:00 Maciej Puzio <mkp37...@gmail.com>: > Paul, many thanks for your reply. > Thinking about it, I can't decide if I'd prefer to operate the storage > server without redundancy, or have it automatically force a downtime, > subjecting me to a rage of my users and my boss. > But I think that the typical expectation is that system serves the > data while it is able to do so.
If you want to prevent angry bosses, you would have made 10 OSD hosts or some other large number so that ceph cloud place PGs over more places so that 2 lost hosts would not impact so much, but also so it can recover into each PG into one of the 10 ( minus two broken minus the three that already hold data you want to spread out) other OSDs and get back into full service even with two lost hosts. It's fun to test assumptions and "how low can I go", but if you REALLY wanted a cluster with resilience to planned and unplanned maintenance, you would have redundancy, just like that Raid6 disk box would presumably have a fair amount of hot and perhaps cold spares nearby to kick in if lots of disks started go missing. -- May the most significant bit of your life be positive.
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