Setting up a synchronous SnapMirror operation

Difference between synchronous and asynchronous SnapMirror

You set up a synchronous SnapMirror operation the same way you set up an asynchronous SnapMirror operation with one exception: the snapmirror.conf file on the destination filer defines the relationship as synchronous rather than defining a schedule for transfers.

The following sections describe setting up a synchronous SnapMirror:

Setting up a basic Synchronous SnapMirror operation

To set up a basic Synchronous SnapMirror operation, complete the following steps.

Note
This procedure assumes you understand basic SnapMirror setup. See Setting up a basic SnapMirror operation for a details.

Step	Action
1	Add previously purchased SnapMirror licenses to the source and destination filers using the `license add` command.
2	On the source filer console, specify the host names of filers that are allowed to copy data directly from the source filer using the `options snapmirror.access` command.
3	On the administration host, create or edit the snapmirror.conf file on the destination filer. The file must specify the volume and a synchronous SnapMirror relationship. Example The following entry specifies synchronous mirroring from vol1 of s_filer and vol2 of d_filer using the default replication arguments. s_filer:vol1 d_filer:vol2 - sync
4	On the source and destination filer consoles, enable SnapMirror using the `snapmirror on` command.
5	On the destination filer console, create the destination volume for the SnapMirror relationship using the `vol create` command.
6	On the destination filer console, mark the volume as restricted using the `vol restrict` command.
7	On the destination filer console, create an initial complete (baseline) copy of the source and start the mirroring process using the `snapmirror initialize` command. Example The following command transfers a complete copy of the source volume to the destination volume and begins synchronous mirroring. snapmirror initialize -S s_filer:vol1 d_filer:vol2

Converting asynchronous SnapMirror to synchronous SnapMirror

If you have an asynchronous SnapMirror relationship and you want to convert it to a synchronous SnapMirror relationship, complete the following step.

Step	Action
1	On the administration host, edit the snapmirror.conf file on the destination filer to change the schedule to `sync`. Result Data ONTAP uses the new schedule to change the asynchronous SnapMirror to a synchronous SnapMirror.

Setting up Synchronous SnapMirror using multiple paths

You might need more than one physical path for a synchronous mirror. Synchronous SnapMirror supports up to two paths for a particular SnapMirror relationship. The paths can be Ethernet, Fibre Channel, or a combination of Ethernet and Fibre Channel. The two paths can be used in one of two modes:

Multiplexing mode--SnapMirror uses both paths at the same time, essentially load balancing the transfers. If one path fails, the transfers occur on the remaining path. After the failed path is repaired, the transfers resume using both paths.
Failover mode--SnapMirror uses the first specified path as the desired path and use the second specified path only after the first path fails.
Note
Asynchronous SnapMirror does not support multiple paths.

To implement multiple paths between the source filer and destination filer, complete the following steps.

Step	Action
1	Ensure that you have two valid paths using the `ping` command from the source filer to each of the IP addresses on the destination filer. Example The IP addresses on the destination filer are 10.10.10.23 and 10.10.10.24. source> `ping 10.10.10.24` 10.10.10.24 is alive source> `ping 10.10.10.23` 10.10.10.23 is alive
2	If you are...	Then...
	Setting up a synchronous SnapMirror for the first time.	Follow the steps shown in Setting up a basic Synchronous SnapMirror operation, substituting the snapmirror.conf step of that procedure (Step 3) with Step 3 and Step 4 of this procedure.
	Converting a single path SnapMirror	Follow Step 3 and Step 4.
3	On the administration host, edit the snapmirror.conf file on the destination filer to add a connection name line that defines the mode of the connection and what the two connections are. The format of the line follows: name = mode (src_filer1, dest_filer1) (src_filer2, dest_filer2) mode is either multi or failover. See the na_snapmirror.conf(5) man page for details.
4	In the same snapmirror.conf file, edit the schedule entry to reflect the new connection name as the source filer.

Example 1

You want to synchronously mirror volume vol1 on a filer called NYC to volume vol1 on a filer called Newark. To satisfy a business requirement that there be two paths between each synchronously mirrored volume, you have four network interface cards, two in each filer. You named the two interfaces on the NYC filer NYC-pri and NYC-sec and the two on the Newark filer Newark-pri and Newark-sec. To implement multiple paths in failover mode, you edit the snapmirror.conf file on Newark to include the following two lines:

NYC-Newark = failover (NYC-pri, Newark-pri) (NYC-sec, Newark-sec)

NYC-Newark:vol1 Newark:vol1 - sync

Example 2

If NYC-pri and Newark-pri are Fibre Channel adapters and you want to replicate data using both connections, you follow the procedure to configure Fibre Channel adapters for SnapMirror. See Configuring for Fibre Channel use. Then you edit the snapmirror.conf file on Newark to include the following two lines to implement multiple paths in multiplexing mode:

NYC-Newark = multi (NYC-pri, Newark-pri) (NYC-sec, Newark-sec)

NYC-Newark:vol1 Newark:vol1 - sync

Setting up a synchronous SnapMirror operation

Difference between synchronous and asynchronous SnapMirror

Setting up a basic Synchronous SnapMirror operation

Example

Example

Converting asynchronous SnapMirror to synchronous SnapMirror

Result

Setting up Synchronous SnapMirror using multiple paths

Example

Example 1

Example 2