Flush file
The flush file tracks where cached datasets are located. It is stored in the prefix directory. Internally, the data of the flush file is organized as a hash. Here are the contents of an example flush file.
DSET
18
LOCATION
PFS
CACHE
DIR
scr.dataset.18
17
LOCATION
CACHE
DIR
scr.dataset.17
Each dataset is indexed by dataset id under the DSET
hash. Then,
under the LOCATION
hash, different flags are set to indicate where
that dataset is stored. The PFS
flag indicates that a copy of this
dataset is stored on the parallel file system, while the CACHE
flag
indicates that the dataset is stored in cache. The same dataset may be
stored in multiple locations at the same time. The DIR
field
specifies the dataset directory name that SCR should use when copying
the dataset to the prefix directory on the parallel file system. At the
end of a run, the flush and scavenge logic in SCR uses information in
this file to determine whether or not the most recent checkpoint has
been copied to the parallel file system.