Thanks all for the responses I got. That was indeed useful information -- our networking team is looking at the TCP window_size and in discussions w/ AT&T (oc3 is leased from AT&T, and as I understand it, it is not a point-to-point router) . - Ravi On Thu, Apr 10, 2008 at 11:47 AM, Tanel Poder <tanel.poder.003@xxxxxxx> wrote: > You might need a more decent SSH client if your current one is > openSSH-based, which apparently does internally limit the send buffer sizes > even if your server defaults / maximum are set higher to math WAN latencies. > > Check this link if you want a high-throughput version of SSH: > http://www.psc.edu/networking/projects/hpn-ssh/ > > 64kB of send buffer for 1600 mile "wide" WAN is too low if you want to > achieve decent throughput. TCP as a reliable transport protocol needs to > have retransmit capability, thus needs to keep all packets in send buffer > until it's acknowledged by the other side, thus low buffer will start > throttling your throughput if the network roundtrip time is long. > > You can actually calculate how large TCP buffers you need if you want to > fill x MB of your Oc3 link. Google for "bandwidth delay product" the formula > is very simple ( only three variables in the formula, link bandwidth, TCP > buffer size and packet transmit time which you can roughly measure with ping > or tnsping ) > > -- > Regards, > Tanel Poder > http://blog.tanelpoder.com > > > ------------------------------ > *From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto: > oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *Ravi Gaur > *Sent:* Wednesday, April 09, 2008 23:39 > *To:* oracle-l@xxxxxxxxxxxxx > *Subject:* Moving DR site from 30miles to 1600miles > > 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 10.2.0.3 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 > >