Re-2: [DRBD-user] bad sync performance !

[Todd Denniston]

Stefan Kerkemeier wrote:
> please look at this:
> 
> kernel: e1000: eth1: e1000_watchdog: NIC Link is Up 1000 Mbps Full Duplex

Looks to me like the hardware may be up to it, that looks close to what my 
cards I have.

> 
> ifconfig eth1
> eth1      Link encap:Ethernet  HWaddr 00:03:47:E0:EB:B1
>           inet addr:10.0.0.3  Bcast:10.0.0.255  Mask:255.255.255.0
>           inet6 addr: fe80::203:47ff:fee0:ebb1/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
<SNIP>

But your MTU looks a bit low to get the performance out of the cards, try

ifconfig eth1 mtu 6000

on both systems.

IIRC the HOWTO used to indicate 9000 instead of my 6k, but for all my hardware 
6k seemed to work out near optimal, and I can now see average syncs of 
~22000KB/s (which is probably maxing out my pathetic raid boxes).

some advice for it seems to be over on the wiki faq now:
http://wiki.linux-ha.org/DRBD_2fFAQ#head-3d7a189ec67920e48d69e294610914e66571de14

and a mention of it in the old article.
http://www.drbd.org/drbd-article.html

> ./iperf -c 10.0.0.2
> ------------------------------------------------------------
> Client connecting to 10.0.0.2, TCP port 5001
> TCP window size: 16.0 KByte (default)
> ------------------------------------------------------------
> [  3] local 10.0.0.3 port 32788 connected with 10.0.0.2 port 5001
> [ ID] Interval       Transfer     Bandwidth
> [  3]  0.0-10.0 sec  1.02 GBytes   872 Mbits/sec
> 
> 
> It´s obvious that it is a gbit link!!!
> 
> drbdsetup /dev/drbd0 show
<SNIP>
> rate = 153600 KB/sec
> group = 1
> al-extents = 257
> 
> system: suse sles9, drbd 0.7.14
> 
> And now, any ideas?
> 
> cheers
> Stefan
> 
<SNIP>