[CentOS] CentOS and Dell MD3200i / MD3220i iSCSI w/ multipath -- slightly OT

Sun Jan 23 06:48:29 UTC 2011
Peter Gillich <pgillich at gmail.com>

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
- 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:

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:

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
- IBM compiles the latest Broadcom driver if required, see:
- Some Dell hardwares have only x86_64 RedHat certifications See:
https://hardware.redhat.com/show.cgi?id=632145 (R310 + RHEL 6)



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
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