Re: Moving DR site from 30miles to 1600miles

From: Mark Brinsmead <>
Date: Wed, 9 Apr 2008 18:43:52 -0600
Message-ID: <>

Silly question: how fast can you SCP a 1GB file locally? 50 MB/min (about 850KB/s) is far from "smoking" fast by todays standards, but SCP *can* be pretty CPU intensive. Maybe 10 years ago, that was nearly as fast as you might expect to go; perhaps even now, if you are starting or ending on a slow or heavily loaded server it still might be.

You may also be affected by other factors. What is the latency on the link?

Have you attempted transfers with another (simpler) protocol, like FTP or "netcat"?

Ooh! Here's a good one: Are you *sure* that your data is actually traversing the OC-3 link? Is is possible that your traffic might be traversing a slower route, for example, through a VPN across the public internet?

I definitely like Jared's idea -- it is probably a good idea to have your network folks put a sniffer on the network, and analyze precisely what is happening with your transfer.

On Wed, Apr 9, 2008 at 9:39 AM, Ravi Gaur <> wrote:

> Hello all,
> We are planning to move our DR site which is currently about 30 miles from
> production site to ~1600 miles away. We currently have a 4-node RAC setup on
> our production site that houses 3 production instances (all on
> Solaris 10). The SAN is Storagetek and we use ASM for volume management.
> In our testing, we are hitting issues in network transfer rates to the
> 1600-miles site -- a simple "scp" of 1GB file takes about 21 minutes. We
> generate archives at the rate of approx 1GB/8minutes. The network folks tell
> me that the TCP setting is a constraint here (currently set to 64k
> window-size which Sysadmins here say is the max setting). We have an Oc3
> link that can transfer @ 150Mbps (that is what the networking team tells
> me).
> I've an SR open w/ Oracle and have also gone thru few Metalink notes that
> talk about optimizing the network from dataguard perspective. One of the
> notes I came across also talks about cascaded standby dataguard setup (one
> standby local pushes logs to the remote site).
> I'm trying to collect ideas how others are doing it under similar
> scenarios and if there is something we can do to utilize the entire network
> bandwidth that we have available to us.
> TIA,
> - Ravi

-- Mark Brinsmead
Senior DBA,
The Pythian Group

Received on Wed Apr 09 2008 - 19:43:52 CDT

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