Defining source and destination through snapmirror.conf

If it does not already exist, use a text editor to create a file called snapmirror.conf in the /etc directory on the root volume of the destination filer.

If you want to add comments to the /etc/snapmirror.conf file, precede the comment with a pound sign (#).

Example

# Replicating from filerA

For each destination volume or qtree that is to be located on this filer, type an entry specifying the source, destination, characteristics and schedule of the data transfer on one line using the following syntax:

source_filer:{source_volume | /vol/volume_name/qtree_name} 
dest_filer:{dest_volume | /vol/volume_name/qtree_name} 
arguments schedule

For a full description of the snapmirror.conf file entry syntax see snapmirror.conf file entry syntax.

Note
When you use a qtree as a source, you do not create another qtree to serve as the destination. SnapMirror automatically creates one for you, using the name you specify. However, you must specify the name of the qtree destination in the volume where you want it to be placed, either in the /etc/snapmirror.conf file or in the snapmirror initialize command.

Note
Do not specify more than 254 destination qtrees for any one volume in your /etc/snapmirror.conf file entries.

If you want to combine all non-qtree data in a volume into a qtree to use as a SnapMirror source, use this syntax:

source_filer:/vol/source_volume/- 
dest_filer:/vol/dest_volume/qtree_name

The dash (-) character indicates all non-qtree data in the specified volume.

Note
The data in /vol/source_volume/- qtree can only be a SnapMirror source, never a destination. That is, after you create the /- qtree, you can copy data from it to another qtree you name, but you cannot copy data to it from another qtree.

Save edits to the file.

src_filer

The name of the filer from which you are copying data. SnapMirror uses the /etc/hosts file or the database used by DNS and NIS for name resolution. When SnapMirror searches for the source filer name, it should find the IP address for the source filer on the network over which you want the transfer to occur.

Example

Assume you created a private network connecting a source filer and a destination filer and you named the interface on the source filer filerA-e0. The interface name filerA-e0 is what you enter in the source_filer field.

src_vol
/src_qtree

The name of the volume or qtree that you are copying. Use the volume name alone for volumes. Use the full path name for qtrees.

Example

If the name of the volume is vol1, enter vol1 in the src_vol/src_qtree field. If the name of the qtree is qtree3, and it is contained in volume vol3, enter the full path, /vol/vol3/qtree3, in the src_vol/src_qtree field.

dest_filer

The host name of the filer to which the data is copied. The name you use must be the exact host name of the destination filer. The dest_filer field is case-sensitive.

You can use the hostname command on the destination filer to determine what you enter for this field.

Example

If the name of the destination filer is filerA, enter filerA in the dest_filer field.

dest_vol
[/dest_qtree]

The name of the destination volume or qtree to which you are copying data. Use the volume name alone for volumes. Use the full path name for qtrees.

Example

If the name of the volume is vol1, enter vol1 in the dest_vol[/dest_qtree] field. If the name of the qtree is qtree4, and it is in vol2, enter the full path, /vol/vol2/qtree4, in the dest_vol[/dest_qtree] field.

kbs=kbs

Maximum transfer speed, in kilobytes per second, that Data ONTAP can use to transfer data.

The kbs and restart arguments are expressed as a comma-separated list of name=value pairs, with no spaces, for example: kbs=2000,restart=always

restart=
{never | always | default}

Restart mode that SnapMirror uses to continue an incremental transfer from a checkpoint if it is interrupted.

There are three options:

• Never--Transfers are always restarted from the beginning of a transfer and never from where they were before an interruption. This mode is useful if you must have the latest data on the destination.
• Always--Transfers are always restarted if possible from where they were before an interruption. This mode is useful for copying large volumes.
• Default--Transfers are restarted if they do not conflict with a scheduled transfer. This is the recommended option.

  SnapMirror always restarts from where the transfer was before an interruption. However, it does not restart if the restart occurs after a scheduled transfer, because the scheduled transfer gives more up-to-date data than the restarted transfer.

The kbs and restart arguments are expressed as a comma-separated list of name=value pairs, with no spaces, for example: kbs=2000,restart=always

cksum=
{none | crc32c}

Selects the checksum algorithm that is used to protect SnapMirror transmitted data. See Improving data protection using checksum for more information.

outstanding=
{xops | xms | xs}

Determines the synchronicity level of the synchronous SnapMirror. The ops suffix allows x number of outstanding write operations before forcing the client to wait for an acknowledgement. The ms and s suffixes allow x number of milliseconds and seconds, respectively. See Controlling the synchronicity level to improve performance for more information.

visibility_
interval={xs | xm | xh}

Determines the amount of time before an automatic snapshot is created on the source volume that is synchronously mirrored. The s, m, and h suffixes specify seconds, minutes, and hours, respectively. See Controlling how quickly data becomes visible on the destination filer for more information.

wsize=size

Determines the TCP window size used by a connection. Different from the snapmirror.window_size option which determines the TCP window size for all snapmirror replications. TCP window size is in bytes. See Changing the TCP window size for a connection for more information.

schedule

Determines the schedule the destination uses for updating data. The schedule is mandatory.

The schedule consists of four space-separated fields in order:

minute hour dayofmonth dayofweek

minute can be a value from 0 to 59.

hour can be a value from 0 (midnight) to 23 (11 p.m.).

dayofmonth can be a value from 1 to 31.

dayofweek can be a value from 0 (Sunday) to 6 (Saturday).

• Multiple values, separated by commas, can be entered for any field.
• All possible values for a field can be applied with an asterisk (*). If you specify an asterisk in each field of the schedule, SnapMirror updates the destination every minute.
• A single dash (-) in any field means "never" and prevents this schedule entry from executing. (This is useful if you want the server to appear in the /etc/snapmirror.conf file so that snapmirror update can find it, but you do not want the SnapMirror scheduler to run automatically.)
• A range of values for any field can be indicated with a low value and a high value separated by a dash. For example, you can indicate that you want an update every hour from 8:00 a.m. to 5:00 p.m by entering this value in the hour field:

  8-17

• A range of values followed by a slash and a number indicates the frequency of the update. For example, you can indicate that you want an update every five minutes by entering this value in the minutes field:

  0-59/5

• Typing sync instead of the four space-separated fields specifies synchronous replication. See Synchronous SnapMirror for more information.