From FusionNetwork

Recently when using a DRBL (Diskless remote boot linux) system for clonezilla backups i ran into this dreaded problem.

  mountd[2592]: refused mount request from 192.168.100.29 for /tftpboot/node_root (/tftpboot/node_root): unmatched host

On the boot client it lists a "Permission denied" when trying to mount root. 

 Needless to say this is a kind of strange issue. The only thing done was the DRBL package was upgraded. Then a drblpush -i ran (to fix the location of /home/partimage). 

 So here is the easy way to fix it!

 Open up your /etc/exports file.

 Change the lines that look like this. 

 /tftpboot/node_root 192.168.100.28(ro,sync,no_root_squash,subtree_check)
/usr 192.168.100.28(ro,sync,no_root_squash,subtree_check)
/opt 192.168.100.28(ro,sync,no_root_squash,subtree_check)
/home 192.168.100.28(rw,sync,no_root_squash,no_subtree_check)
/var/spool/mail 192.168.100.28(rw,sync,root_squash,no_subtree_check)
/tftpboot/storage/backup 192.168.100.28(rw,sync,no_root_squash,no_subtree_check)

To look like this.  (note the addition of the "insecure" line.)

 /tftpboot/node_root 192.168.100.29(ro,sync,no_root_squash,insecure,subtree_check)
/usr 192.168.100.29(ro,sync,no_root_squash,insecure,subtree_check)
/opt 192.168.100.29(ro,sync,no_root_squash,insecure,subtree_check)
/home 192.168.100.29(rw,sync,no_root_squash,insecure,no_subtree_check)
/var/spool/mail 192.168.100.29(rw,sync,root_squash,insecure,no_subtree_check)
/tftpboot/storage/backup 192.168.100.29(rw,sync,no_root_squash,insecure,no_subtree_check)

Also change.

 /tftpboot/nodes/192.168.100.28/ 192.168.100.28(rw,sync,no_root_squash,no_subtree_check)

To this. 

 /tftpboot/nodes/192.168.100.29/ 192.168.100.29(rw,sync,no_root_squash,insecure,no_subtree_check)

And there you have it.