[Samba] Strange Performance Issue / concurrent clients -> very very slow

[José Guzmán]

  Is the new GBit iSCSI storage connected on the same collision domain 
as the other machines?

  If so, you may be hitting the limit of the switch. Try separating 
iSCSI from the rest of the network with another switch, or at least a 
separate VLAN.

Greetings

  José

On 10/28/2011 10:04 AM, Götz Reinicke wrote:
> Hi,
>
> recently I installed a new GBit connected iSCSI Storage to one of our
> fileservers. Redhat EL Linux 5.7 samba3x-3.5.4-0.83.el5, kernel
> 2.6.18-238.19.1.el5PAE, Dell Poweredge 1750, dual Xeon.
>
> The transfer speed is very very different, depending on the method I
> use. Currently I'm the only user accessing that server and there is low
> network traffic.
>
> I know, that there are some overheads etc. which influence the speed.
>
> My Test Client is a Macbook pro  and a Mac Pro (OS X 10.6.x each,
> connected by GBit wired lan)
>
> I copy a couple of 30 MB files and in an other test files of 1GB.
>
> Transferspeed for ftp is about 85 MB/s, scp about 25 MB/s, samba 30 MB/s.
>
> So the 'raw' speed is o.k. for me, more that 30 MB would be nice.
>
> BUT the most confusing thing is, as soon as I copy files from two
> clients at the same time to my samba share, the performance drops to 5
> MB/s for each client. So 10 MB/s.
>
> Transferring from two ftp clients is about 40 MB/s per client.
>
> Currently I use 'socket options = TCP_NODELAY SO_RCVBUF=8192
> SO_SNDBUF=8192 IPTOS_LOWDELAY'
>
> Dose anybody has an explanation for such a poor performance? Any tunig
> tips or hints? Everything is welcome.
>
> 	Thanks and best regards. Götz
>
>
>