Based on the above performance characteristics for home directory services planning and management, the following guidelines are included and recommended within this paper to satisfy capacity requirements for a successful home directory services platform:
- While an application-driven workload hosted on a PowerScale storage cluster may require that the cluster be sized first for performance, and second for capacity, the reduced SLAs typically in effect around home directories often mean that disk space is the primary consideration when planning for an adequate home directory services solution that leverages PowerScale storage.
- Even with SmartQuotas policies in effect, organizations may have exceptions policies that allow certain users or data types to bypass the standard quota enforcement restrictions. Policies that are less restrictive may result in the home directories data set growing faster than upfront planning would have suggested.
- Different users may warrant different quota settings. Rather than a single per-user capacity quota and a single exceptions policy for all users, consider a tiered quota approach, in which different categories of users (for example, managers and IT administrators) are allocated a higher quota than other users.
- Some organizations use a stair-step approach to quota-policy allocation, for example, a base 10GB policy for most users, then a 25GB policy for the next tier of users, then 50GB, then 100GB, and so on. This approach allows administrators to increase user quotas as necessary without removing them entirely for the largest home directories.
- While SmartQuotas may provide a constraining factor on data growth, the use of snapshots on home directories has the opposite effect: more frequent snapshots lead to automatic increases in the amount of space in use, and the length of the retention policy (that is, the standard lifecycle of a single snapshot) determines how long that disk space will remain in use.
- SmartQuotas capacity-restriction policies can be configured to include or exclude the overhead associated with SnapshotIQ data.
- In addition to raw disk space, the PowerScale unique architecture means that capacity planning also needs to apply when considering the number of user connections per node that will be required to provide acceptable performance for home directory data. These considerations and recommendations are listed in SmartConnect considerations and guidelines.