Again, may be the best option that I can think of...but will it really be equal to your total write rate? What if a block changes 32 times in 5 seconds. I think semi sync is going to be at best every 3 seconds (i am actually asking and confirming that) and thus all 32 of those writes may end up only being 1 or 2 blocks traversing circuit sm is using.

--Jordan

On Mon, Jan 14, 2019 at 12:36 PM Fenn, Michael fennm@deshawresearch.com wrote:

One thing you could do is to look at the write rate over time via your favorite tool (statistics show, OCUM, OCI, Harvest, etc.). Assuming the goal is to have async SnapMirror “keep up”, all writes effectively need to be journaled to the remote site. The bandwidth required would correspond to the total write rate.

Thanks,

Michael

*From: *toasters-bounces@teaparty.net on behalf of jordan slingerland < jordan.slingerland@gmail.com> *Date: *Monday, January 14, 2019 at 11:14 AM *To: *Basil basilberntsen@gmail.com *Cc: *"toasters@teaparty.net" toasters@teaparty.net *Subject: *Re: Bandwidth Calculator for Exiting NetApp

Best way I can think of ,though,potentially async sm may have a higher change rate dependent on work load and current sm schedule.

For example, a block might change once every 5 seconds but snapmirror once every hr will only catch 1 block change every hour.

On Mon, Jan 14, 2019 at 10:40 AM Basil basilberntsen@gmail.com wrote:

I use an older version of ontap (9.1) with the old fashioned snapmirror (DP, not XDP), but basically the estimate should be based on the cumulative snapshot delta, minus potential compression.

Snapshot show-delta is the command to see the delta between any two snapshots.

On Mon, Jan 14, 2019 at 9:27 AM Mike Michalakis mike@directit.com.cy wrote:

I’m wondering how anyone approaches the following scenario:

We have an existing NetApp system in place (ONTAP 9.4), currently taking Snapshots of all the required volumes as per the required RPO objectives as defined.

The question is:

There is now a requirement to implement a DR site using Asynchronous Snapmirror, based on the current snapshots and rate of change, what is an estimated bandwidth requirement to meet X RPO.

What tools or options are available for completing such an exercise or the methodology

Thanks

MikeM

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