Fortinet recommends using the default RAID level specified in the FortiAnalyzer data sheet, that is, RAID 50. If your configuration does not meet RAID 50 requirements, consider upgrading your hardware.
When planning for disk space requirements, consider future storage needs. Adding disks to an existing RAID array requires rebuilding the RAID array and restoring backed up logs.
The disk space available for you to set log quotas depends on the RAID level and the reserved space for temporary files. Temporary files are needed for indexing, reporting, and file management. In your planning, include both the disk space for the original logs FortiAnalyzer receives (Archive) and the space required to index the logs (Analytics).
Fortinet recommends using the default ratio of Analytics : Archive for most deployments. If you plan to retain archive logs for a much longer period than your analytical data, you might allocate a higher percentage to Archive.
If you need more disk space for a VM, you can add a virtual disk.
You can also increase the size of an existing virtual disk. No format is required.
execute lvm extend command to add or extend virtual disks. See the FortiAnalyzer CLI Reference.