illumos gate

When a zfs property is set, replicated, changed on the receiving dataset and sent back, the updated value is hidden by the original local value.

In the case where datasets are replicated for disaster recovery purposes if the DR copy is ever made live and zfs properties are updated the primary copy will not get the updated values when send via zfs send/receive.

zfs receive needs to be able to have an option to cause automatically do a 'zfs inherit -S' on any received properties.

This script demonstrates the programmatic problem of received properties hiding behind local properties:

#!/bin/bash -x

pool="dozer" 

zfs create $pool/test1

# Set a standard property and a user property
zfs set user:property="test1" $pool/test1
zfs set sharenfs="rw=@10.0.0.0/8" $pool/test1
zfs set user:property3="test1" $pool/test1

# Make a snapshot
zfs snapshot $pool/test1@snap1

# Replicated to a new dataset
zfs send -R $pool/test1@snap1 | zfs receive -F -v $pool/test2

# Show the properties on the replication
zfs get sharenfs,user:property,user:property2,user:property3 $pool/test2

# Change the properties on the replicated copy
zfs set user:property="test2" $pool/test2
zfs set user:property2="test2" $pool/test2
zfs set sharenfs="rw=@192.168.0.0/16" $pool/test2

# Make a new snapshot on the replication copy
zfs snapshot $pool/test2@snap2

# Replicate back to the orginal dataset
zfs send -R -I $pool/test2@snap1 $pool/test2@snap2 | zfs receive -F -v $pool/test1

# Show the properties on the original, notice the missing updates listed as local

zfs get sharenfs,user:property,user:property2,user:property3 $pool/test1

# The properties sharenfs and user:property have no received values, only local

zfs get -s received sharenfs,user:property,user:property2,user:property3 $pool/test1

# We can get them back by inheriting the received values.
# However, this operation is risky because we cannot programtically tell if there are received values.

zfs inherit -S sharenfs $pool/test1
zfs inherit -S user:property $pool/test1
zfs inherit -S user:property2 $pool/test1
zfs inherit -S user:property3 $pool/test1

zfs get sharenfs,user:property,user:property2,user:property3 $pool/test1

# On dataset test2 user:property2 was not received, but we don't always know this.
# Running 'inherit' on it with -S makes it go away.

zfs get sharenfs,user:property,user:property2,user:property3 $pool/test2
zfs inherit -S sharenfs $pool/test2
zfs inherit -S user:property $pool/test2
zfs inherit -S user:property2 $pool/test2
zfs inherit -S user:property3 $pool/test2
zfs get sharenfs,user:property,user:property2,user:property3 $pool/test2

echo "Press enter to destroy test datasets" 

read nothing

zfs destroy -r $pool/test1
zfs destroy -r $pool/test2