5.6 HP StorageWorks X9000 File Serving Software User Guide (TA768-96035, June 2011)

There is no guarantee as to the order in which the two rules will be executed; therefore, the final
destination is ambiguous because multiple rules can apply to the same file.
Example 2:
Rules can cause data movement in both directions, which can lead to issues. In the following
example, the rules specify that all .doc files in tier 1 to be moved to tier 2 and all .jpg files in
tier 2 be moved to tier 1. However, this might not succeed, depending on how full the tiers are.
# ibrix_migrator -A -f ifs2 -r ' name = "*.doc" ' -S T1 -D T2
# ibrix_migrator -A -f ifs2 -r ' name = "*.jpg" ' -S T2 -D T1
For example, if tier 1 is filled with .doc files to 70% capacity and tier2 is filled with .jpg files to
80% capacity, then tiering might terminate before it is able to fully "swap" the contents of tier 1
and tier 2. The files are processed in no particular order; therefore, it is possible that more .doc
files will be encountered at the beginning of the job, causing space on tier 2 to be consumed faster
than on tier 1. Once a destination tier is full, obviously no further movement in that direction is
possible.
These rules in these two examples are ambiguous because they give rise to possible conflicting
file movement. It is the user’s responsibility to write unambiguous rules for the data tiering policy
for their file systems.
Writing tiering rules 115