Re: [Iscsitarget-devel] kernel Error message

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On Tue, 2008-09-30 at 16:51 -0400, Evgeny Yurchenko wrote:
> 
> Hi Ming!
> 
> Thanks for quick response. All iscsi-target are configured in blockio
> mode. The server is IntelPentium4 CPU 3.00GHz,  2GB RAM and Adaptec
> 2820SA RAID-card with 8 SATA 3.0MB/s drives configured in RAID5. Before

i would say you disk array might be a bottleneck... how many NVRAM u
have in RAID controller?

and you export this raid5 as a whole? or some other io share the raid?

is this target only for log (pretty sequential) or also for mail?

> putting this server in production we burned it with much higher iscsi
> load (measuring network load) and there were no errors. I just want you
> to confirm the next:

ic. did u test fileio mode before?

> 
> This error tells us that INITIATOR did reset connection because did not
> receive confirmation from TARGET that read/write operation complete in
> timely manner. Correct?

yes

> And two more questions if you do not mind:
> 1) how can installing more memory help?

i thought u use fileio, so memory is not issue here.

> 2) is it possible that this is network issue?

could be. but u need to check u switch to see if any routing issue,
packet loss.... or run tcpdump to check packet timing, for a high
traffic like this. maybe u have to grab couple GB logs...

> 
> Thanks!
> Eugene.
> 
> -----Original Message-----
> From: Ming Zhang [mailto:bla...@gm...] 
> Sent: September 30, 2008 4:36 PM
> To: Roman Naumenko
> Cc: isc...@li...; Evgeny Yurchenko
> Subject: Re: [Iscsitarget-devel] kernel Error message
> 
> On Tue, 2008-09-30 at 16:00 -0400, Roman Naumenko wrote:
> > Hello,
> > 
> > We have a few errors per day in /var/log/messages on one of most
> > loaded SAN servers:
> > 
> > kernel: iscsi_trgt: Logical Unit Reset (05) issued on tid:1 lun:0 by
> > sid:1971425271414848 (Function Complete)
> > 
> > As we discovered this error appears when Exchange heavily writes logs
> > on target device.
> > We are still investigating disk loads on the server trying to figure
> > out if error are actually related to disk load.
> 
> yes. it is. ini sends a command to target and the command takes too long
> to complete. and then ini issues a reset. 
> 
> using a faster disk if possible, if you use 64bit os, add more ram if
> possible.
> 
> and u might want to use blockio or async mode.
> 
> 
> but should not cause data loss, ...
> 
> 
> > 
> > The system is rPath Linux 2.3 and kernel is
> > 2.6.24.7-0.5.1.smp.gcc3.4.x86.i686
> > 
> > We use openfiler system on SANs. Now we are discussing with openfiler
> > developers if NICs issues might be a problem - but there are no
> > dropped packets on the server side. On the initiators side all
> > additional options are disabled (like TCPOffload Engine)
> > 
> > What is your opinion about this issue?
> > 
> > Best regards,
> > Roman Naumenko
> > 
> > Network Administrator
> > Frontline Technologies
> > 
> > HelpDesk: (416) 637-3132
> > 
> > rom...@fr...
> > http://www.frontline.ca
> >
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