ceph_ec_calc

Introduction

Ceph erasure coding calculator python3

USE AT OWN RISK: TESTING, IMPROVEMENTS, COMMENTS WELCOME

• run with no args to produce an example output - (using servers,drives,capacity with some defaults)
• -t for tabulate
• --help to see help

To calculate use either:

• servers,drives,capacity... (we assume servers*drives = osd count)
• osds,capacity...

Example outputs

Two equivalent calculations are shown below. The EC scheme and resultant numbers are just for an example here...

OSD based calculation

----
**** Using --osds NOT --servers ****
----
-c 12 | Using DRIVE|OSD_SIZE (TB) 12
-o 72 | Using OSD_COUNT 72
Results in RAW (TB) 864
----
-k 4 | Using K (min copy) of 4
-m 2 | Using M (resiliancy) of 2
----
EFFICIENCY RATIO
0.667
----
FULL CAPACITY (TB) AT 100% **NOT RECOMMENDED!**
576.0
----
80% CAPACITY (TB) - RECOMMENDED MAX FOR CEPH (SAFE CAPACITY RESERVERVATION)
460.8

The same with -t

Drive|OSD Size(TB)    nOSDs    K    M    EFFICIENCY RATIO    100% CAPACITY (TB)    80% CAPACITY (TB)
--------------------  -------  ---  ---  ------------------  --------------------  -------------------
                  12       72    4    2               0.667                   576                460.8

Server based calculation - where assumption is servers*drives = osd count

----
**** Using --servers NOT --osds ****
----
-c 12 | Using DRIVE|OSD_SIZE (TB) 12
-d 12 | Using DRIVE|OSD_PER_SERVER 12
-s 6 | Using SERVER_COUNT 6
Results in SERVER_SIZE (TB) 144
Results in RAW (TB) 864
----
-k 4 | Using K (min copy) of 4
-m 2 | Using M (resiliancy) of 2
----
EFFICIENCY RATIO
0.667
----
FULL CAPACITY (TB) AT 100% **NOT RECOMMENDED!**
576.0
----
80% CAPACITY (TB) - RECOMMENDED MAX FOR CEPH (SAFE CAPACITY RESERVERVATION)
460.8

The same with -t

Drive|OSD Size(TB)    Drives|OSD Per Server    Servers    K    M    EFFICIENCY RATIO    100% CAPACITY (TB)    80% CAPACITY (TB)
--------------------  -----------------------  ---------  ---  ---  ------------------  --------------------  -------------------
                  12                       12          6    4    2               0.667                   576                460.8