Volume and LUN Provisioning
This domain tests how SVMs, flexible volumes, junctions, LUNs, and igroups deliver file and block storage.
Volumes and namespace
An SVM owns volumes, LIFs, and its namespace. A flexible volume is mounted into the namespace with a junction path; the SVM root volume holds the namespace root. Volumes are thin by default: volume guarantee none lets a volume report more logical size than currently allocated space. volume guarantee volume reserves the full capacity. Snapshot reserve sets aside space for Snapshot copies, and autosize can grow a volume within limits.
LUNs and access
SAN LUNs are created inside a volume and mapped to an igroup. Match the LUN OS type to the initiator, and use selective LUN mapping or portsets where appropriate. LUN space reservation and fractional reserve control how much backing space is guaranteed.
Worked example
Create a 1 TB volume with 5% snapshot reserve and guarantee none, then a 800 GB LUN with space reservation disabled. The LUN fits logically, but the volume does not physically reserve 800 GB. If the LUN fills and snapshots accumulate, the volume can run out of space. Enabling volume guarantee or LUN reservation would protect writes but consumes capacity up front.
Traps
Creating a LUN larger than usable volume capacity; confusing snapshot reserve with snapshot autodelete; choosing the wrong igroup OS type; and forgetting that a volume must be junctioned before NFS clients can traverse it.