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

PAulN pauln at psc.edu
Fri Dec 2 01:08:24 CET 2005

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


The mtu is small but I don't think it's the culprit here.  Perhaps if
the resync was getting 30 or 40MB/sec you could blame the mtu.

How much cpu is being used during the resync operation (on both machines)?
paul

Todd Denniston wrote:

> 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>
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