You could also set osd_crush_initial_weight = 0 . New OSDs will automatically come up with a 0 weight and you won't have to race the clock.
-Brett
On Thu, Oct 4, 2018 at 3:50 AM Janne Johansson <icepic.dz@xxxxxxxxx> wrote:
_______________________________________________Den tors 4 okt. 2018 kl 00:09 skrev Bruno Carvalho <brunowcs@xxxxxxxxx>:Hi Cephers, I would like to know how you are growing the cluster.
Using dissimilar hardware in the same pool or creating a pool for each
different hardware group.
What problem would I have many problems using different hardware (CPU,
memory, disk) in the same pool?I don't think CPU and RAM (and other hw related things like HBA controller card brand) mattersa lot, more is always nicer, but as long as you don't add worse machines like Jonathan wrote youshould not see any degradation.What you might want to look out for is if the new disks are very uneven compared to the oldsetup, so if you used to have servers with 10x2TB drives and suddenly add one with 2x10TB,things might become very unbalanced, since those differences will not be handled seamlesslyby the crush map.Apart from that, the only issues for us is "add drives, quickly set crush reweight to 0.0 beforeall existing OSD hosts shoot massive amounts of I/O on them, then script a slower raise ofcrush weight upto what they should end up at", to lessen the impact for our 24/7 operations.If you have weekends where noone accesses the cluster or night-time low-IO usage patterns,just upping the weight at the right hour might suffice.Lastly, for ssd/nvme setups with good networking, this is almost moot, they converge so fastits almost unfair. A real joy working with expanding flash-only pools/clusters.--May the most significant bit of your life be positive.
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