What is an acceptable transfer rate?
What is considered an acceptable backup data transfer rate, given today's solutions, measured in GB/hr per drive?
To further define the parameters, say I had 10 LTO 1 drives in a robotic library, backing up a 10TB FC SAN (80% NAS hosting W2K data and 20% server hosts, MS and Notes apps.). No UNIX. Factor in a weekly full for all 10TB (1.43TB per night avg.) and a data change rate of 20% (300GB of incremental per night avg.).
As far as I'm concerned, the only acceptable transfer rate is at least
125% of the rated native transfer rate of the drive, on average. I usually go for about 150%. Another way to say this would be about
75%-80% of the compressed speed. I architect everything I do based on that.
I do all sorts of things to achieve that, including:
1. Tweaking multistreaming (how many backups are run at once).
2. Tweaking multiplexing (how many backups go to a given drive at once).
3. Adding disk to the mix to deal with low bandwidth networks.
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This was first published in November 2003