You can perform a scan that reallocates every block in a LUN, file, or volume regardless of the current layout by using the -f option of the reallocate start command. A full reallocation optimizes layout more aggressively than a normal reallocation scan. A normal reallocation scan moves blocks only if the move improves the layout of a LUN, file, or volume. A full reallocation scan always moves blocks, unless the move makes the layout even worse.
Using the -f option of the reallocate start command implies the -o and -n options. This means that the full reallocation scan is performed only once, without checking the layout first.
You might want to perform this type of scan if you add a new RAID group to a volume and you want to ensure that blocks are laid out sequentially throughout the volume or LUN.
If a full reallocation scan fails because of space issues, consider performing reallocation scans on a per-file basis, by using reallocate start file_pathname without any options. However, if the space issue is caused by a full reallocation on a file or LUN that was performed without the -p option, a long-term solution is to wait until the Snapshot rotation has freed space on the volume and then to rerun the full reallocation scan with the -p option.
This option also reallocates the shared blocks in a deduplicated volume. Reallocation scans skip deduplicated data if you do not specify the -p option. You can use this option only with FlexVol volumes, with files and LUNs within FlexVol volumes, or with deduplicated volumes.
Do not use -p when you start a reallocation scan on a compressed volume. Starting a reallocation scan on a compressed volume using -p does not optimize the layout of a volume.