Disk quotas are managed partition by partition. There is no relation between each partition and quotas setup. Further, you may enable disk quotas on some partitions while disabling them on others.
You can control disk quota user per user. You can also work at the group level. Both quotas are set up completely independently. A group with a hundred users may have a disk space quota of much less than the sum of the users' quotas.
When a file is created by a user, it belongs to that user and to some group. The disk quotas of both the user and the group are updated.
A user may have plenty of available disk quota, but the group may be out of quota. Because of that, the user won't be able to use more disk space while active in that group. This will not prevent them from doing work in another group assuming that the space is available. However, they will need to switch to that group before this can occur.
Linuxconf lets you manage quotas with great flexibility. While you can configure the quota limits user by user, most administrators will choose to operate more globally. Further, linuxconf lets you partially fill quota specifications. This lets you use some defaults for a user and override only a single specification (the maximum files allowed for example).
You can control two aspects with disk quotas: (1) the number of files and directories owned by a user (or group) and (2) the amount of disk space owned. Both options are controlled separately. It is possible to have no limit on one, while enforcing some limits on the other.
Each aspect is controlled by three parameters:
A given limit may have three values:
Disk quotas for a user are influenced by three setups:
Disk quotas for a group are influenced by two setups: