[CentOS] CentOS and Dell MD3200i / MD3220i iSCSI w/ multipath

Sat Jan 22 00:18:01 UTC 2011
Edward Morbius <dredmorbius at gmail.com>

On Fri, Jan 21, 2011 at 3:58 PM, Ross Walker <rswwalker at gmail.com> wrote:

> On Jan 21, 2011, at 6:41 PM, Edward Morbius <dredmorbius at gmail.com> wrote:
>
> We've been wrestling with this for ... rather longer than I'd care to
> admit.
>
> Host / initiator systems are a number of real and virtualized CentOS 5.5
> boxes.  Storage arrays / targets are Dell MD3220i storage arrays.
>
> ...
>
>
> You need the RDAC kernel module installed, this handles asymmetric
> multipathing to these devices.
>
> You can get this from Dell's site.
>
> Once this is installed you need to setup dm-multipath, look for
> multipathd.conf in /etc, get the product id and vendor id from dmesg after
> making an initial connection via open-iscsi and use that in the mutipath
> config. Your going to need to use path utility 'rdac' in the config instead
> of tur.
>
> Google is your friend here.
>

We've got *an* rdac module installed.  Any way of telling whether or not
this is Dell's?  RPM says these are from kernel-2.6.18-194.17.1.el5.src.rpm.

$ lsmod | grep rdac
scsi_dh_rdac           43977  0
scsi_dh                42177  2 scsi_dh_rdac,dm_multipath
scsi_mod              196953  14
scsi_dh_rdac,be2iscsi,ib_iser,iscsi_tcp,bnx2i,cxgb3i,libiscsi2,scsi_transport_iscsi2,scsi_dh,sr_mod,sg,libata,megaraid_sas,sd_mod

$ rpm -qif $(locate rdac.ko)
Name        : kernel                       Relocations: (not relocatable)
Version     : 2.6.18                            Vendor: CentOS
Release     : 194.17.1.el5                  Build Date: Wed 29 Sep 2010
11:57:11 AM PDT
Install Date: Thu 14 Oct 2010 02:17:14 PM PDT      Build Host:
builder10.centos.org
Group       : System Environment/Kernel     Source RPM:
kernel-2.6.18-194.17.1.el5.src.rpm
Size        : 96488290                         License: GPLv2
Signature   : DSA/SHA1, Thu 30 Sep 2010 08:35:49 AM PDT, Key ID
a8a447dce8562897
URL         : http://www.kernel.org/
Summary     : The Linux kernel (the core of the Linux operating system)
Description :
The kernel package contains the Linux kernel (vmlinuz), the core of any
Linux operating system.  The kernel handles the basic functions
of the operating system:  memory allocation, process allocation, device
input and output, etc.
Name        : kernel                       Relocations: (not relocatable)
Version     : 2.6.18                            Vendor: CentOS
Release     : 194.17.1.el5                  Build Date: Wed 29 Sep 2010
11:57:11 AM PDT
Install Date: Thu 14 Oct 2010 02:17:14 PM PDT      Build Host:
builder10.centos.org
Group       : System Environment/Kernel     Source RPM:
kernel-2.6.18-194.17.1.el5.src.rpm
Size        : 96488290                         License: GPLv2
Signature   : DSA/SHA1, Thu 30 Sep 2010 08:35:49 AM PDT, Key ID
a8a447dce8562897
URL         : http://www.kernel.org/
Summary     : The Linux kernel (the core of the Linux operating system)
Description :
The kernel package contains the Linux kernel (vmlinuz), the core of any
Linux operating system.  The kernel handles the basic functions
of the operating system:  memory allocation, process allocation, device
input and output, etc.


There's also a rebuild of 'sg', with a source tree in /usr/src/sg-3.5.34dell

Diffing sources:

$ diff sg.c sg.c_rhel5
22c22
< #define SG_VERSION_STR "3.5.34dell"
---
> #define SG_VERSION_STR "3.5.34"
1879c1879
<         sg->length = (ret_sz > num) ? num : ret_sz;
---
>         sg->length = ret_sz;

I'll also note that Dell isn't playing nice with its package installs --
some stuff is under /opt/dell, some is installed via RPM, some appears to be
tossed arbitrarily onto the system:

$ rpm -qif /lib/modules/2.6.18-194.17.1.el5/extra/sg.ko
file /lib/modules/2.6.18-194.17.1.el5/extra/sg.ko is not owned by any
package

Bad Dell.  No donut.


>
> -Ross
>
>
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>


-- 
Dr. Ed Morbius
Chief Scientist
Krell Power Systems Unlimited
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