Dell PowerVault NX3610 - Manual (Page 19)

FluidFS v3 Support Matrix 15
11 Space Pre-Allocation
This section provides a good estimation of the pre-allocated (reserved) space for various filesystem
functions. It can assist with the estimation of disk space requirements and space growth of FluidFS
systems.
Table 11-1 reserved space by function
File-System Function Allocated
per
Reserved space
Cache relocation Pair/Appliance 144GB *
Mapping Structures Pair/Appliance 16GB *
Continuous metadata journaling Pair/Appliance 96GB *
Safety buffers Pair/Appliance 20GB
Data Reduction Pair/Appliance 100GB **
Space management LUN 4GB
Data Integrity health scan Total Space 0.5%
* For NX3500 pairs the value should be halved
** V3 only (V2 systems do not support Data Reduction). Please notice that the Data Reduction
space (100GB per pair) is pre-allocated during upgrade to V3. If there is not enough free space to
accommodate this growth, the upgrade may fail.
The amount of reserved space can also be estimated using the table below:
NAS Pool Size Percentage of Reserved Space
10TB - 20TB 2% - 4%
20TB - 50TB 1% - 2%
> 50TB < 1 %