CentOS - Jan 2011 - CentOS and Dell MD3200i / MD3220i iSCSI w/ multipath -- slightly OT

Greetings,

On 1/22/11, Edward Morbius <dredmorbius at gmail.com>
wrote:
> CentOS is not a Dell-supported configuration, and we've had little
helpful
> advice from Dell.  There's been some amount of FUD in that Dell
don't seem
> to know what Dell's own software installation (the md3
>
> Dell doesn't seem to have much OS experience generally.
>
+1

It is to be expected from Dell as they outsource support to non-"equal
opportunity" employers who do not hire support agents beond 40 years
of age (per HR).

Above fact. below imho

Now, experience often helps reach the source of the problem much
faster that fast-talking street-smart agents who proliferated.

It is sad that IT industry treats its early community members so callously.

I don't know but Dell seems to be headed the Sun way -- open for
takeover by HP/IBM

Above imho.

Regards,

Rajagopal

on 23:06 Sat 22 Jan, Rajagopal Swaminathan (raju.rajsand at gmail.com)
wrote:
> Greetings,
> 
> On 1/22/11, Edward Morbius <dredmorbius at gmail.com> wrote:
> > CentOS is not a Dell-supported configuration, and we've had little
helpful
> > advice from Dell.  There's been some amount of FUD in that Dell
don't seem
> > to know what Dell's own software installation (the md3
> >
> > Dell doesn't seem to have much OS experience generally.
> >
> 
> +1
> 
> It is to be expected from Dell as they outsource support to non-"equal
> opportunity" employers who do not hire support agents beond 40 years
> of age (per HR).
We actually had a very good experience earlier with server hardware
(PowerEdge R610 and R410 systems).  Helpful, proactive, dug up some
recent tech, even provided a significant amount of replacement RAM
should that have proved to be the problem (it wasn't).  The storage side
of the house is an entirely different animal.

The issue BTW was ECC memory errors (disabling C-State in BIOS was the
fix).

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

Hi,
In last summer, I have had same problems with Dell + CentOS +
multipath combination. For example I/O errors and stability problems
on the initiator machines. The initator machines are (in a Pacemaker
cluster):
- Dell R310
- Broadcom?5709 Gigabit Ethernet card (4-port)
- CentOS 5.4
- 2 Ethernet ports on initiator machines, 2 Ethernet ports in target
machines --> 4 iSCSI pathes by initiators

Irrespectively of iSCSI, we met the Broadcom MSI-X interrupt problem
(corrected in RHEL/CentOS 5.5). We met more (iSCSI) problems with
Broadcom cards, which are described on a Dell support page:
http://support.dell.com/support/edocs/software/rhel_mn/rhel5_4/en/index.htm

Since the CentOS is a recompiled RedHat, all RHEL problems and
solutions are true for CentOS ;-)
The Broadcom driver source code is frequently changed. RedHat follows
the Broadcom kernel drivers and iscsi-initiator-utils with some months
latency. CentOS follows the RedHat with some days/weeks/monts.

Maybe you can find a solution for your problem on a newer Dell support
page:
http://support.dell.com/support/edocs/software/rhel_mn/rhel5_5/en/index.htm
Or here:
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/DM_Multipath
http://opensource.marshall.edu/papers/rhel5-iscsi-HOWTO.pdf

Some tips:
- I've read somewhere about iSCSI multipath I/O errors, which can be a
normal behaving in a multipath environment at boot time. (?)
- Persistent reservation might be usefult against iSCSI multipath I/O errors.
- Disabling iSCSI offload feature (for example: iSCSI over Broadcom )
and TCP offload feature (for example: NFS over Intel) may be helps.
- The iSCSI kernel drivers and iscs-initiator-utils must be updated together.

Finally, some comments:
- Never use Broadcom GbE card. Intel might be better (mostly)
- The Dell is hardware manufacturer (supplier), not an
OS/driver/utility developer. If you would like to get more support,
you may buy RHEL licenses (with the Dell hardware or from RedHat).
Sometime it's cheaper than taking days for a problem (but sometime
not).
- IBM compiles the latest Broadcom driver if required, see:
http://www-947.ibm.com/support/entry/portal/docdisplay?lndocid=MIGR-5073130
- Some Dell hardwares have only x86_64 RedHat certifications See:
https://hardware.redhat.com/show.cgi?id=632145 (R310 + RHEL 6)

BR,

Peter

On Sat, Jan 22, 2011 at 18:36, Rajagopal Swaminathan
<raju.rajsand at gmail.com> wrote:
>
> Greetings,
>
> On 1/22/11, Edward Morbius <dredmorbius at gmail.com> wrote:
> > CentOS is not a Dell-supported configuration, and we've had little
helpful
> > advice from Dell. ?There's been some amount of FUD in that Dell
don't seem
> > to know what Dell's own software installation (the md3
> >
> > Dell doesn't seem to have much OS experience generally.
> >
>
> +1
>
> It is to be expected from Dell as they outsource support to non-"equal
> opportunity" employers who do not hire support agents beond 40 years
> of age (per HR).
>
> Above fact. below imho
>
> Now, experience often helps reach the source of the problem much
> faster that fast-talking street-smart agents who proliferated.
>
> It is sad that IT industry treats its early community members so callously.
>
> I don't know but Dell seems to be headed the Sun way -- open for
> takeover by HP/IBM
>
> Above imho.
>
> Regards,
>
> Rajagopal
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos