[OpenAFS] replication over slower bandwidth

Wed, 1 Feb 2012 08:19:14 +0000

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Hi

What is the network's loss and delay characteristics between the two? =
i.e is it a LAN connect? is it WAN - we successfully replicate volumes =
of 2/3GB over 400k ADSL (while doing other things over the line) over a =
OpenVPN connection, what was important to us was to get the =
fragmentation under control so that packet loss at the transmission =
layer matched what AFS though was a packet - otherwise things really =
ground to a halt and transactions failed.

Unless the link between the two end points is close to perfect (in terms =
of loss and delay variance) I would be very careful in making RX packets =
span multiple UDP packets on the transmission medium, check MTU sizes =
carefully.

Don't set your expectations at 3mbit/s AFS data transfer - there are =
headers to be accounted for - check what level of the protocol Iperf is =
really reporting at.

Neil

On 31 Jan 2012, at 19:24, muayad y wrote:

> Hi,
>   I am trying to replicate RO volume 31GB on server, where upload =
speed 6Mbit/s and download speed ~24Mbit/s on that server. However, =
replication is taking so long ~ 1.3 Mbit/s. with Iperf  over UDP can =
obtain up 3Mbit/s, when using -bandwidth option. =20
>=20
> - I am wondering if there is similar option that I can pass to =
volserver ?
> - read volserver docs and there is -udpsize option, the docs does not =
say much, so I am not sure how to use it, or if I need to change linux =
kernel params to make it work.
>=20
> Thanks for your help.=20
>=20
>=20

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<html><head></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space; =
">Hi<div><br></div><div>What is the network's loss and delay =
characteristics between the two? i.e is it a LAN connect? is it WAN - we =
successfully replicate volumes of 2/3GB over 400k ADSL (while doing =
other things over the line) over a OpenVPN connection, what was =
important to us was to get the fragmentation under control so that =
packet loss at the transmission layer matched what AFS though was a =
packet - otherwise things really ground to a halt and transactions =
failed.</div><div><br></div><div>Unless the link between the two end =
points is close to perfect (in terms of loss and delay variance) I would =
be very careful in making RX packets span multiple UDP packets on the =
transmission medium, check MTU sizes =
carefully.</div><div><br></div><div>Don't set your expectations at =
3mbit/s AFS data transfer - there are headers to be accounted for - =
check what level of the protocol Iperf is really reporting =
at.</div><div><br></div><div>Neil</div><div><br><div><div>On 31 Jan =
2012, at 19:24, muayad y wrote:</div><br =
class=3D"Apple-interchange-newline"><blockquote type=3D"cite"><table =
cellspacing=3D"0" cellpadding=3D"0" border=3D"0"><tbody><tr><td =
valign=3D"top" style=3D"font: inherit;">Hi,<br>&nbsp; I am trying to =
replicate RO volume 31GB on server, where upload speed 6Mbit/s and =
download speed ~24Mbit/s on that server. However, replication is taking =
so long ~ 1.3 Mbit/s. with Iperf&nbsp; over UDP can obtain up 3Mbit/s, =
when using -bandwidth option.&nbsp; <br><br>- I am wondering if there is =
similar option that I can pass to volserver ?<br>- read volserver docs =
and there is -udpsize option, the docs does not say much, so I am not =
sure how to use it, or if I need to change linux kernel params to make =
it work.<br><br>Thanks for your help. =
<br><br><br></td></tr></tbody></table></blockquote></div><br></div></body>=
</html>=

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