On 08/03/17 11:05, Dan van der Ster wrote: > On Fri, Jul 28, 2017 at 9:42 PM, Peter Maloney > <peter.malo...@brockmann-consult.de> wrote: >> Hello Dan, >> >> Based on what I know and what people told me on IRC, this means basicaly the >> condition that the osd is not acting nor up for any pg. And for one person >> (fusl on irc) that said there was a unfound objects bug when he had size = >> 1, also he said if reweight (and I assume crush weight) is 0, it will surely >> be safe, but possibly it won't be otherwise. >> >> And so here I took my bc-ceph-reweight-by-utilization.py script that already >> parses `ceph pg dump --format=json` (for up,acting,bytes,count of pgs) and >> `ceph osd df --format=json` (for weight and reweight), and gutted out the >> unneeded parts, and changed the report to show the condition I described as >> True or False per OSD. So the ceph auth needs to allow ceph pg dump and ceph >> osd df. The script is attached. >> >> The script doesn't assume you're ok with acting lower than size, or care >> about min_size, and just assumes you want the OSD completely empty. > Thanks for this script. In fact, I am trying to use the > min_size/size-based removal heuristics. If we would be able to wait > until an OSD is completely empty, then I suppose could just set the > crush weight to 0 then wait for HEALTH_OK. For our procedures I'm > trying to shortcut this with an earlier device removal. > > Cheers, Dan Well what this is intended for is you can set some weight 0, then later set others weight 0, etc. and before *all* are done, you can remove *some* that the script identifies (no pgs are on that disk, even if other pgs are still being moved on *other* disks). So it's a shortcut, but only by gaining knowledge, not by sacrificing redundancy.
And I wasn't sure what you preferred... I definitely prefer to have my full size achieved, not just min_size if I'm going to remove something. Just like how you don't run raid5 on large disks, and instead use raid6, and would only replace one disk at a time so you still have redundancy. What do you use so keeping redundancy isn't important?
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