Understanding disks, RAID and usable storage
An offer showing several drives describes raw hardware capacity. The space available to your application depends on the selected RAID layout, filesystem, reserved space and any replication. Ask for a usable-capacity estimate before deciding that a configuration is large enough.
Check the proposed layout
- Identify the drive count, capacity and type, and which drives hold the operating system, database and other application data.
- Confirm whether RAID is implemented in hardware or software, the intended redundancy level and the procedure for a failed drive.
- Allow space for growth, logs, temporary files, updates and rebuild activity. Filling a filesystem can disrupt applications.
- Specify an independent backup plan. RAID can help with certain disk failures, but it does not reverse accidental deletion or application corruption.
Do not initialise drives, recreate arrays or change controller settings on a live server without a reviewed migration and recovery plan. For a storage alert, send the service reference and the exact warning before attempting a repair.
