NetApp PowerShell Toolkit 101: Data Protection

Protecting data is arguably the most important job that your storage is entrusted with. Losing data is simply not an option, so it’s critical to protect data through the use of backups and replication.

There are different ways that you can replicate data in your clustered Data ONTAP system. First, you can replicate to a separate volume of the same SVM in the cluster. Second, to a volume that belongs to a different SVM in the same cluster. Finally, replication can be configured with another cluster entirely.

In this post we will cover:

Peering Relationships
- Cluster Peers
- SVM Peers
SnapMirror Policies
SnapMirror
- Version Flexible SnapMirror
SnapVault
Load Sharing Mirrors

If you are interested in additional detail about SnapMirror and SnapVault in clustered Data ONTAP 8.3, please see the post I did over at DatacenterDude.com.

Peering Relationships

The first steps for configuring replication relationships is to configure the cluster and SVM to peer with each other. This is only necessary when you are traversing the respective boundaries. For example, if you are SnapMirroring to a volume which belongs to the same SVM as the source, you do not need to configure peer relationships.

Note: You will need to configure at least one inter-cluster LIF (ICL) before you can replicate between clusters.

Cluster Peers

# show current peers
Get-NcClusterPeer

# create a peer
Add-NcClusterPeer -Address $peerIclAddress -Credential (Get-Credential)

# check peer connectivity for ICLs
Get-NcClusterPeer -Name $clusterPeerName | Get-NcClusterPeerHealth

# remove a peer
Get-NcClusterPeer -Name $clusterPeerName | Remove-NcClusterPeer

# show current peers

Get-NcClusterPeer

# create a peer

Add-NcClusterPeer -Address $peerIclAddress -Credential (Get-Credential)

# check peer connectivity for ICLs

Get-NcClusterPeer -Name $clusterPeerName | Get-NcClusterPeerHealth

# remove a peer

Get-NcClusterPeer -Name $clusterPeerName | Remove-NcClusterPeer

SVM Peers

# show current peers
Get-NcVserver -Name $svmName | Get-NcVserverPeer

# create a new SVM peer relationship
New-NcVserverPeer -Vserver $svmName -PeerCluster $remoteClusterName `
  -PeerVserver $remoteSvmName -Application snapmirror

# after submitting a peering request, you will need to confirm the
# relationship on the destination cluster
Confirm-NcVserverPeer -Vserver $localSvmName -PeerVserver $removeSvmName

# remove all peers for an SVM
Get-NcVserver -Name $svmName | Get-NcVserverPeer | Remove-NcVserverPeer

# show current peers

Get-NcVserver -Name $svmName | Get-NcVserverPeer

# create a new SVM peer relationship

New-NcVserverPeer -Vserver $svmName -PeerCluster $remoteClusterName `

-PeerVserver $remoteSvmName -Application snapmirror

# after submitting a peering request, you will need to confirm the

# relationship on the destination cluster

Confirm-NcVserverPeer -Vserver $localSvmName -PeerVserver $removeSvmName

# remove all peers for an SVM

Get-NcVserver -Name $svmName | Get-NcVserverPeer | Remove-NcVserverPeer

SnapMirror Policies

The SnapMirror policy, and it’s constituent rules, determine the type of protection relationship, which snapshots to transfer, and the number of snapshot copies to keep at the destination.

# view policy details
Get-NcSnapmirrorPolicy -Name $policyName

# create a policy
$splat = @{
    # a unique name for the policy
    'Name' = $newPolicyName;

    # whether or not to restart if interrupted
    'Restart' = 'always';

    # async_mirror = SnapMirror, vault = SnapVault
    # mirror_vault = both
    'Type' = 'async_mirror';

    # use, or not, network compression
    'EnableNetworkCompression' = $true;
}

New-NcSnapmirrorPolicy @splat

# enable network compression for an existing policy
Get-NcSnapmirrorPolicy -Name $policyName | 
  Set-NcSnapmirrorPolicy -EnableNetworkcCompression $true

# view policy details

Get-NcSnapmirrorPolicy -Name $policyName

# create a policy

$splat = @{

# a unique name for the policy

'Name' = $newPolicyName;

# whether or not to restart if interrupted

'Restart' = 'always';

# async_mirror = SnapMirror, vault = SnapVault

# mirror_vault = both

'Type' = 'async_mirror';

# use, or not, network compression

'EnableNetworkCompression' = $true;

}

New-NcSnapmirrorPolicy @splat

# enable network compression for an existing policy

Get-NcSnapmirrorPolicy -Name $policyName |

Set-NcSnapmirrorPolicy -EnableNetworkcCompression $true

SnapMirror

SnapMirror replicates a volume between source and destination, relying on SnapShots to determine what data has changed (or been added) and therefore needs to be replicated.

The life cycle of a SnapMirror relationship has many different phases, roughly in the following order:

Initialize – this is the initial data transfer
Update – resyncs the volumes, transferring any new and changed data
Quiesce – finishes current update, then disables future resync operations. Normally a precursor to ending the relationship.
Resume – resumes updating the mirror after it has been quiesced or broken.
Break – after being quiesced, this will make the destination volume writable.
Resync – after the reason for making the destination writable has gone away (testing? disaster?), resync the relationship to the current state at the source.

There are three types of SnapMirror relationship. The first one is data protection. This is what is commonly referred to as simply “SnapMirror” in the NetApp lexicon. It is a protection relationship which replicates data from the source volume to a read-only “DP” volume. This type of relationship is meant to provide disaster recovery protection by allowing the destination volume to be made writable if necessary.

Note that when creating this relationship type, the destination volume must have a type of dp.

SnapMirror is controlled from the destination, which means that all of the PowerShell commands should be targeted at the destination cluster.

# show protected volumes, note this will display both
# mirrored and vaulted volumes
Get-NcSnapmirror

# show mirrored volumes
Get-NcSnapmirror | Where-Object {
    $_.RelatiopnshipType -eq "data_protection"
}

# show unhealthy relationships (both mirror and vault)
Get-NcSnapmirror | Where-Object { $_.IsHealthy -eq $false }

# show lag time for relationships (both mirror and vault)
Get-NcSnapmirror | Select-Object SourceLocation,DestinationLocation,`
  @{ 'N'="Lag Time Hours"; 'E'={ [Math]::Round($_.LagTime / 60 / 60, 2) } }

# create a new SnapMirror relationship
$splat = @{
    # the cluster is optional
    "Source" =  "$srcCluster://$srcSvmName/$srcVolumeName";

    # cluster is again optional if you are not configuring
    # replication between two clusters
    "Destination" = "$dstCluster://$dstSvmName/$dstVolumeName";

    # dp = SnapMirror
    "Type" = "dp";

    # DPDefault = SnapMirror
    # or use a custom policy of your own with a type of async-mirror
    "Policy" = "DPDefault";

    # view the available policies using the 
    # Get-NcJobCronSchedule cmdlet
    "Schedule" = "daily"
}

New-NcSnapmirror @splat

# initialize the relationship
Invoke-NcSnapmirrorInitialize -Source "$srcCluster://$srcSvmName/$srcVolumeName" `
  -Destination "$dstCluster://$dstSvmName/$dstVolumeName"

# manually update a relationship
Invoke-NcSnapmirrorUpdate -Source "$srcCluster://$srcSvmName/$srcVolumeName" `
  -Destination "$dstCluster://$dstSvmName/$dstVolumeName"

# quiesce and break the relationship
Invoke-NcSnapmirrorQuiesce -Source "$srcCluster://$srcSvmName/$srcVolumeName" `
  -Destination "$dstCluster://$dstSvmName/$dstVolumeName"
Invoke-NcSnapmirrorBreak -Source "$srcCluster://$srcSvmName/$srcVolumeName" `
  -Destination "$dstCluster://$dstSvmName/$dstVolumeName"

# resync the relationship (note that his will cause any
# changes since the last SnapMirror snapshot on the 
# destination to be lost)
Invoke-NcSnapmirrorResync -Source "$srcCluster://$srcSvmName/$srcVolumeName" `
  -Destination "$dstCluster://$dstSvmName/$dstVolumeName"

# release a relationship.  this will remove 
# snapshots related to the relationship from the source
# and destination volumes.  after releasing, the relationship
# cannot be resumed with a reinitialization.
Invoke-NcSnapmirrorRelease -Source "$srcCluster://$srcSvmName/$srcVolumeName" `
  -Destination "$dstCluster://$dstSvmName/$dstVolumeName"

# show protected volumes, note this will display both

# mirrored and vaulted volumes

Get-NcSnapmirror

# show mirrored volumes

Get-NcSnapmirror | Where-Object {

$_.RelatiopnshipType -eq "data_protection"

}

# show unhealthy relationships (both mirror and vault)

Get-NcSnapmirror | Where-Object { $_.IsHealthy -eq $false }

# show lag time for relationships (both mirror and vault)

Get-NcSnapmirror | Select-Object SourceLocation,DestinationLocation,`

@{ 'N'="Lag Time Hours"; 'E'={ [Math]::Round($_.LagTime / 60 / 60, 2) } }

# create a new SnapMirror relationship

$splat = @{

# the cluster is optional

"Source" = "$srcCluster://$srcSvmName/$srcVolumeName";

# cluster is again optional if you are not configuring

# replication between two clusters

"Destination" = "$dstCluster://$dstSvmName/$dstVolumeName";

# dp = SnapMirror

"Type" = "dp";

# DPDefault = SnapMirror

# or use a custom policy of your own with a type of async-mirror

"Policy" = "DPDefault";

# view the available policies using the

# Get-NcJobCronSchedule cmdlet

"Schedule" = "daily"

}

New-NcSnapmirror @splat

# initialize the relationship

Invoke-NcSnapmirrorInitialize -Source "$srcCluster://$srcSvmName/$srcVolumeName" `