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SnapMirror Replication Scheduling Spreadsheet

February 21st, 2009

I created an Excel spreadsheet as I was tasked with creating a SnapMirror replication schedule for a customer that only had an 8meg line. The problem was that the replication would fail if more than 1 transferred happened at the same time. So I needed a way of calculating the rate of change, and designing the replication based on this.

The spreadsheet will calculate the snapmirror.conf schedule, but will also give you the commands to create, restrict and initialize the volumes.

I’ve not protected the spreadsheet, so adapt it all you like, but I’d appreciate any feedback from people that have taken this and improved or adapted it.


Sections that are meant to be editable…

Source Filer: Enter the name of the SnapMirror source filer. The spreadsheet is designed to work per destination filer, so put in as many different sources as you need, each line is calculated independently.

Destination Filer: The spreadsheet is designed to be per destination filer, so just fill in the top record. Potentially you can change this per line if you want.

Volume: This is the name of the primary volume. The destination volume is created as sourcefiler_sourcevolume as this was created as a shared platform, so I needed to be able to differentiate.

Size: The size in GB of the source volume. The spreadsheet shows most of it’s workings, so you can see how it breaks the GB size down into MB, then rate of change.

Start Time (24 hour): This allows you to alter the start time of the replication schedule. You may have a tape backup that needs to run at midnight, or another operation so you want to start the replication later in the morning, or any time of day to be honest!

Rate of Change: This is calculated from the right hand percentage value, but you may want to manually enter a more accurate rate of change if it’s known.

Over the far right of the spreadsheet is some constants that apply to the whole page.

Global Daily Rate of Change: A percentage rate of change. This was useful as I didn’t know the actual rate of change at the time. Ideally you would know the exact rate of change and fill in the column to the left.

Bandwidth Available: This is in megabits/sec, the spreadsheet converts this into megabytes for it’s calculations.

Variant on Schedule: This allows you to put padding around each schedule in case of errors on the line, or variations in the rate of change.

Thin Provisioned Destination Volume: This is the size that the “vol create” command will thin provision the volumes to. I never create the destination volume to the same size, and always thin provision so as changes to the primary volume will automatically allow the destination to grow to within the thin provisioned limits.

Hopefully you all find this useful, but feedback is much appreciated.

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  1. | #1

    Thanks man , very useful tool ,too bad i found it after snapmirror was configured

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