A Mini How-to from Joerg Moellenkamp July 24, 2012,
Volume 173, Issue 4
In his post Find out in-depth information about a file in ZFS Joerg Moellenkamp explains how to determine the block size of a database file created prior to having set the record size of the filesystem to the same as the database. In such a case, he point out, just looking at the recordsize property of zfs doesn't help, as what displays is the recordsize currently set, not the one set at file creation time. Moellenkamp's method involves the inode number of the object in combination with the file name, in response to which ZFS will return the block size.