Bandwidth required for SRDF/Asynchronous replication in DMX3 and DMX3

Posted on 2010-11-28
Medium Priority
Last Modified: 2012-05-10
How much is the bandwidth (Mbps or kbps)required  between local and remote DMX3 or DMX4  symmetrix arrays in SRDF /Asynchronous Replication ?
Question by:faraz81116
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Expert Comment

by:Duncan Meyers
ID: 34228028
You have to determine the rate of change of the data. How much data do you have and what is the rate of change? The size of incremental backups will give you an indication.

Author Comment

ID: 34228375
This was asked to me in an interview
can you give any  one scenario by taking any example date and rate of change .and how incremental backups will give  an indication.

we use symcli commands
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Accepted Solution

Duncan Meyers earned 2000 total points
ID: 34234863

You're weekly full backup is 100GB. You're daily incremental backup is 3GB, so file rate of change is 3%. You can now estimate your block rate as it will be less than the file rate of change at one third of the file rate of change, so block rate of change is 1%. !5 of 100GB is 1GB. Most of that change occurs over an 8 hour window during production hours, so:

1000MB / 8 hours = 125MB/hr
125MB / 3600 = .03472 MB/second, or 34KB/sec
34KB/sec x 8 = 277Kb/sec (note change from Bytes to bits). If you want to be conservative, change the factor from 8 to 10 to allow for Ethernet and IP overheads.
So, if you have to replicate 1GB per working day, you need a serial link that can handle 277Kb/sec. I would typically increase this number to allow for the peaky nature of replication workloads, and the fact that you can't really purchase a 277Kb serial link. You'd want a 1Mb/sec link at a minimum. This will allow you to maintain the RPO.

The formula scales to any data size.
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Author Comment

ID: 34236203
thats great i got idea how stuff works
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Expert Comment

by:Duncan Meyers
ID: 34486157
Works for me!
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Expert Comment

ID: 34514890
This question has been classified as abandoned and is being closed as part of the Cleanup Program.  See my comment at the end of the question for more details.

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