zfs send and receive and use of /bin/dd in 9.1

[noprobs]

Can anyone enlighten me why zfs send is now piped twice through /bin/dd obs=1m

/sbin/zfs send %s%s%s | /bin/dd obs=1m | /bin/dd obs=1m | %s -p %d %s "/sbin/zfs receive -F -d %s && echo Succeeded.

This appears to have been added between 8.3 and 9.1. It is referenced in this post http://forums.freenas.org/threads/local-zfs-replication-to-san-volume.10248/ but with no definitive reason for it,

Many thanks.

 

[William Grzybowski]

This is done to reduce the chance of blocking the zfs process with the pipe syscall..