Lots of distributed filesystems (I guess I'm talking about distributed object stores here rather than an actual clustered network filesystem) rely on a regular POSIX filesystem for the storage of blobs.
A huge amount of work has gone into making ext4/zfs/xfs etc fast and reliable, plus you get other benefits like journaling, filesystem caching, fsync(), metadata caching (a la ZFS), so there are credible arguments for not going down the path of NIH.
A huge amount of work has gone into making ext4/zfs/xfs etc fast and reliable, plus you get other benefits like journaling, filesystem caching, fsync(), metadata caching (a la ZFS), so there are credible arguments for not going down the path of NIH.