[Samba] Aplication slow after migration

Felipe Martinez Hermo felipe at galicia.ugt.org
Wed Feb 6 09:19:49 GMT 2008

Sinisa Bandin escribió:
> Felipe Martinez Hermo wrote:
>>>> OK, so we're apples to apples, so to speak; the servers are tuned 
>>>> the same.  I'll assume your disks are tuned from hdparm and up to 
>>>> snuff, otherwise you wouldn't be tuning sockets ;).  Did your old 
>>>> server have samba settings for oplocks set?
>>>> -- 
>>>> Peace and Blessings,
>>>> -Scott.
>>>> "Of course, that's just my opinion; I could be wrong"
>>>> -Dennis Miller 
>>> Erm, sorry, I didn't catch that you had 2 .conf files there.  I'm 
>>> back to the drawing board.  Sorry about that.  Anyone else have any 
>>> ideas?
>> Yes, that's whats shocking me. Apparently we're apples to apples. 
>> Except for the kernel (new&slow 2.6.18-4-686 vs old&fast 2.6.8)
>> I've sniffed both eth0 interfaces and I've got some more information. 
>> When talking to the slow server, the client needs to send 76 "TCP 
>> segment of a reassembled PDU" that are not sent when talking to the 
>> old and fast server.
>> How can I workaround this issue? Should I lower server's MTU? How much?
>> Thank you
> Do you happen to have a Realtek 8169 based gigabit ethernet in new 
> server?
> If you do, I had the same problem several times last year, and solved 
> all of them by changing motherboards (all were integrated, and I like 
> them to stay that way because I can achieve full gigabit speed with 
> several concurent clients)
> Best regards,
> Sinisa Bandin

No, machines are out-of-the-box HP DL servers:
Ethernet controller: Broadcom Corporation NetXtreme BCM5705_2 Gigabit 
Ethernet (rev 03)

I've made a spreadsheet with summarizing wireshark results and comparing 
results for both servers. You can see it here: 

It's meaningful that fast server makes 406 Trans2 calls, while slow 
server makes 616 calls to perform the same operation. The difference is 
mainly in QUERY_PATH_INFO (200 vs 305) and FIND_FIRST2 (94 vs 199) calls.

Next try: change ethernet wire?  :-?

Felipe Martínez Hermo
felipe at galicia.ugt.org
fmartinez at galicia.ugt.org
Servicios Informáticos
UGT Galicia
informatica at galicia.ugt.org
ugtgalicia at gmail.com

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