# Limits on the size of a PoN

LeeTL1220
Arlington, MAMember, Broadie, Dev

in GATK 4 Beta

Due to a shortcoming in the Java interface of the underlying storage space (HDF5), a single matrix cannot exceed a number of bytes equal to MAX_INT, which is 2147483647

Therefore, S x T x 8 < 2147483647, where S is the number of samples and T is the number of targets.

In a simpler form: S x T < 268435455

This is usually only an issue for WGS PoNs. In this case, we recommend setting larger binsize (e.g. 5000) to avoid a very large number of targets (T).