<font size=2 face="sans-serif">Hello Hannes,</font>
<br>
<br><font size=2 face="sans-serif">sorry for top-posting, but crappy Notes
is not really a good client for mailing-list - at least I don't know how
to avoid such mess.</font>
<br>
<br><font size=2 face="sans-serif">The output is </font>
<br>
<br><font size=2 face="sans-serif">[root@fru3710e ~]# sg_inq /dev/sdc</font>
<br><font size=2 face="sans-serif">standard INQUIRY:</font>
<br><font size=2 face="sans-serif"> PQual=0 Device_type=0 RMB=0
version=0x04 [SPC-2]</font>
<br><font size=2 face="sans-serif"> [AERC=0] [TrmTsk=0] NormACA=1
HiSUP=1 Resp_data_format=2</font>
<br><font size=2 face="sans-serif"> SCCS=0 ACC=0 TPGS=0
3PC=0 Protect=0 BQue=0</font>
<br><font size=2 face="sans-serif"> EncServ=0 MultiP=1 (VS=1)
[MChngr=0] [ACKREQQ=0] Addr16=0</font>
<br><font size=2 face="sans-serif"> [RelAdr=0] WBus16=0 Sync=0
Linked=0 [TranDis=0] CmdQue=1</font>
<br><font size=2 face="sans-serif"> [SPI: Clocking=0x0 QAS=0
IUS=0]</font>
<br><font size=2 face="sans-serif"> length=193 (0xc1)
Peripheral device type: disk</font>
<br><font size=2 face="sans-serif"> Vendor identification: EMC
</font>
<br><font size=2 face="sans-serif"> Product identification: Invista
</font>
<br><font size=2 face="sans-serif"> Product revision level: 5100</font>
<br><font size=2 face="sans-serif"> Unit serial number: CKM00xxxxxxxxx
</font>
<br>
<br><font size=2 face="sans-serif">and well, 'weightedpath' is also available
in RHEL, but only queries for the device name and the SCSI-address. I wanted
to query the remote-port of the storage-device - which is the frontend
wwn of the storage device.</font>
<br>
<br><font size=2 face="sans-serif">Cheers,</font>
<br>
<br><font size=2 face="sans-serif">Andreas</font>
<br>
<br>
<br>
<br>
<br>
<br><font size=1 color=#5f5f5f face="sans-serif">From:
</font><font size=1 face="sans-serif">Hannes Reinecke <hare@suse.de></font>
<br><font size=1 color=#5f5f5f face="sans-serif">To:
</font><font size=1 face="sans-serif">dm-devel@redhat.com,
</font>
<br><font size=1 color=#5f5f5f face="sans-serif">Date:
</font><font size=1 face="sans-serif">11.01.2013 08:28</font>
<br><font size=1 color=#5f5f5f face="sans-serif">Subject:
</font><font size=1 face="sans-serif">Re: [dm-devel]
Priozier for remote port on fibre channel devices</font>
<br><font size=1 color=#5f5f5f face="sans-serif">Sent by:
</font><font size=1 face="sans-serif">dm-devel-bounces@redhat.com</font>
<br>
<hr noshade>
<br>
<br>
<br><tt><font size=2>On 01/11/2013 08:11 AM, <br>
Andreas.Bleischwitz@continental-corporation.com wrote:<br>
> Hello List,<br>
><br>
> I'm currently facing a problem with a storage virtualization device<br>
> which is located in two different datacenters and shows up as<br>
> another path to a configured SAN-LUN.<br>
> The virtualization device is from EMC² and is called V-PLEX.<br>
><br>
> So I have something like this:<br>
><br>
> DC A<br>
> Host ---VPLEX-DC A---LUN storage A<br>
> | |<br>
> ..|...........|...................<br>
> | DC B |<br>
> ------VPLEX-DC B---LUN storage B<br>
><br>
> The VPLEX device itself is for storage based mirroring and<br>
> synchronizes write access to storage A to storage B and the other<br>
> way around.<br>
><br>
> My problem is, that the virtual LUN I get from the VPLEX does not<br>
> have any prioritization given by dm-multipath and looks like this:<br>
><br>
> mpath3 (36000144000000010e06d8f12ec30dfef) dm-9 EMC,Invista<br>
> [size=5.0G][features=1 queue_if_no_path][hwhandler=0][rw]<br>
> \_ round-robin 0 [prio=1][active]<br>
> \_ 5:0:1:2 sdad 65:208 [active][ready]<br>
> \_ 5:0:4:2 sdak 66:64 [active][ready]<br>
> \_ 5:0:5:2 sdap 66:144 [active][ready]<br>
> \_ 4:0:0:2 sdc 8:32 [active][ready]<br>
> \_ 4:0:1:2 sdh 8:112 [active][ready]<br>
> \_ 4:0:4:2 sdo 8:224 [active][ready]<br>
> \_ 4:0:5:2 sdt 65:48 [active][ready]<br>
> \_ 5:0:0:2 sdy 65:128 [active][ready]<br>
><br>
> That way, write access is made round-robin and access to the<br>
> "remote-devices" - device located in the other DC - creating<br>
> duplicate traffic through the<br>
> SAN switches as the access has to be routed to the remote VPLEX-B<br>
> and it will write to the local VPLEX-A.<br>
><br>
> I wanted to solve this problem by giving priorities to a path by its<br>
> remote-port - which is different for each connection to a SAN<br>
> device. Unfortunately<br>
> there currently doesn't exist any priorizer and I have to write one<br>
> on my own.<br>
> To make the definition flexible, I would like to have a file with
a<br>
> list of port-wwns associated with a priority.<br>
><br>
> For versions shipped with RHEL5 this could be a simple shell script<br>
> which simply looks up the sysfs file structures of a given device.<br>
> For RHEL6 this has to be<br>
> a binary library. So writing a binary version will make more sense<br>
> than maintaining two different solutions.<br>
><br>
<br>
Well, at least on SLES we're shipping a prioritizer named <br>
'weightedpath' which does exactly this.<br>
<br>
However, chances are that the VPLEX is supporting ALUA, so you might <br>
want to use the 'alua' prioritizer here.<br>
<br>
What is the output of 'sg_inq /dev/sdc' ?<br>
<br>
Cheers,<br>
<br>
Hannes<br>
-- <br>
Dr. Hannes Reinecke
zSeries & Storage<br>
hare@suse.de
+49 911 74053 688<br>
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg<br>
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)<br>
<br>
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