Crystal clear, thanks ! On 13/01/2014 18:25, Kyle Bader wrote: > Hi Loic, > >> IIRC you figured out how to use https://github.com/ceph/ceph-tools/tree/master/models . Do you happen to have some kind of HOWTO or even the list of commands you've used to get me started ? > > git clone ...ceph-tools > cd ceph-tools/models/reliability > ./main.py -g > > At this point a graphical form should pop up and most of it should be > straight forward. NRE rate is non recoverable read errors, the NRE > model determines how an array/disk responds to a non recoverable read > error event. I tend to be on the conservative end having seen my share > of RAID horror shows so I set the NRE model to "fail". The other > gotcha is most disk manufacturers use MTBF or AFR while the > reliability modeling tool requests FITS. The formula you will need is: > > MTBF = 1,000,000,000 x 1/FIT. [1] > > Stripe length is the number of RADOS objects that are require to store > a blob of data, ie all RADOS objects that compose a RBD volume. Since > this code was written a while ago there is no code to support modeling > erasure coded objects. If you have any questions, let me know! > > [1] http://en.wikipedia.org/wiki/Failure_rate#Units > -- Loïc Dachary, Artisan Logiciel Libre
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