Fractional reserve

If you have enabled space reservation for a file or files, you can reduce the space that you preallocate for those reservations using fractional reserve. Fractional reserve is an option on the volume, and it can be used with either traditional or FlexVol volumes. Setting fractional reserve to less than 100 causes the space reservation held for all space-reserved files in that volume to be reduced to that percentage. Writes to the space-reserved files are no longer unequivocally guaranteed; you must monitor your reserved space and take action if your free space becomes scarce.

Fractional reserve is generally used for volumes that hold LUNs with a small percentage of data overwrite.

Note
If you are using fractional reserve in environments where write errors due to lack of available space are unexpected, you must monitor your free space and take corrective action to avoid write errors.

For more information about fractional reserve, see your Block Access Management Guide.