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The SAN storage ledger ordering columns are as follows:
- Storage performance level
- Type of storage performance
- Type of replication (none, local or remote)
- Capacity requested
- Forecast date
- Project name
The SAN storage ledger storage capacity columns are determined by:
- Environment (data center, virtual storage array environment, major business unit)
- Disk performance and type (high speed, SATA, etc.)
- Storage types (mirrored data center to data center, instant copy using local snapshots of data)
Besides storage end users, data storage administrators also place entries into the storage ledger. SAN storage admins may create ledger entries to forecast storage infrastructure needs because of lease expirations, to reserve temporary staging capacity needed for storage maintenance, and to document the impact of future storage realignments such as the effect of transferring data between storage tiers or technologies (e.g., SAN to NAS).
NAS and backup administrators may also write checks against the SAN storage environment. A NAS administrator is required to create a SAN ledger entry to track removal of storage from a NAS gateway that's slated to migrate to NAS Fibre-attached storage (FAS). A backup admin might write a check to request more disk pool storage for online disk backups.
NAS storage ledger
When the NAS storage ledger process started, the NAS environment at Ford Motor Company was more complicated than it is today. The environment consisted of multiple vendors with both gateway-based NAS (NAS devices connected to external storage-area networks administered by the SAN team) and FAS-based network-attached storage (NAS gateway heads built into OEM vendor-provided Fibre-attached storage arrays).
For gateway-based NAS, the NAS administrators are required to write SAN storage ledger checks to increase or decrease NAS gateway SAN capacity. The old system used tape-based Network Data Management Protocol (NDMP), which meant entries had to be made in the backup ledger. Ford has been migrating to a pure FAS-based NAS environment with a non-tape backup infrastructure supplied by a single vendor. In addition, only a single performance type of NAS storage is now offered. As a result, the NAS ledger has become simpler to reflect the less-complicated environment.
From a customer perspective, the NAS entries are the amount of data needed and the location of primary storage; the capacity columns track the amount of primary and backup mirrored storage requested. When there are a lot of small entries for the NAS ledger, they're bundled together to reflect a forecastable amount. NAS team entries consist of mainly major projects, a bundle of small projects for a specific month and organic growth predictions. NAS file systems that aren't protected by file system size quotas are the main causes of organic growth.
This was first published in January 2010