Re: [ceph-users] How to calculate the nearfull ratio ?

2017-05-04 Thread Gregory Farnum
On Thu, May 4, 2017 at 5:30 AM Loic Dachary wrote: > Hi, > > In a cluster where the failure domain is the host and dozens of hosts, the > 85% default for nearfull ratio is fine. A host failing won't suddenly make > the cluster 99% full. In smaller clusters, with 10 hosts or less, it is > likely t

Re: [ceph-users] How to calculate the nearfull ratio ?

2017-05-04 Thread Loic Dachary
On 05/04/2017 03:58 PM, Xavier Villaneau wrote: > Hello Loïc, > > On Thu, May 4, 2017 at 8:30 AM Loic Dachary > wrote: > > Is there a way to calculate the optimum nearfull ratio for a given > crushmap ? > > > This is a question that I was planning to cover in th

Re: [ceph-users] How to calculate the nearfull ratio ?

2017-05-04 Thread Xavier Villaneau
Hello Loïc, On Thu, May 4, 2017 at 8:30 AM Loic Dachary wrote: > Is there a way to calculate the optimum nearfull ratio for a given > crushmap ? > This is a question that I was planning to cover in those calculations I was working on for python-crush. I've currently shelved the work for a few w

Re: [ceph-users] How to calculate the nearfull ratio ?

2017-05-04 Thread Yair Magnezi
from our experience even 80% is a 'dangerous zone' ( unfortunately this is how it goes ... and it is quiet wasteful comparing to other solutions ) On Thu, May 4, 2017 at 3:57 PM, David Turner wrote: > The Ceph Enterprise default is 65% nearfull. Do not go above 85% nearfull > unless y

Re: [ceph-users] How to calculate the nearfull ratio ?

2017-05-04 Thread David Turner
The Ceph Enterprise default is 65% nearfull. Do not go above 85% nearfull unless you are stuck while backfilling and need to increase it to add/remove storage. Ceph needs overhead to be able to recover from situations where disks are lost. I always take into account what would happen to the %full i

[ceph-users] How to calculate the nearfull ratio ?

2017-05-04 Thread Loic Dachary
Hi, In a cluster where the failure domain is the host and dozens of hosts, the 85% default for nearfull ratio is fine. A host failing won't suddenly make the cluster 99% full. In smaller clusters, with 10 hosts or less, it is likely to not be enough. And in larger clusters 85% may be too much t