Microsoft boot from SAN lun 0 read-only attribute

Question

When we provision a windows host on a VMAX we present a 50Gb boot lun at lun 0. When storage is presented on the initial install lun 0 is marked as read-only and the intel admin has to use the diskpart utility to clear the attribute. If we only present just a lun 0 it is not marked read-only; this happens when we present the boot lun and additional luns. This is all prior to loading the operating system or anything on our standard HP server with emulex LP11000/LP12000 HBA's. This is on a VMAX using thin provisioning and masking views; director flags are preset on at the HBA level. I am trying to find out what is causing the read-only attribute to be picked up by the server as the disk is read/write on the storage array.

HP server model is 380/580

Emulex HBA LP11000/12000

Windows 2008 R2 64bit

VMAX 20K runing 5876 enginuity

Thin provisioning

Masking view with dual pathing

Boot from SAN

Kleanthis76 · Accepted Answer

Hi Robert,

Based on the following MS article: http://support.microsoft.com/kb/2345135

this is the default behavior for your OS based on the SAN Policy.

Also you can check the white-paper from EMC: EMC Symmetrix with Windows Server 2003 and 2008 Best Practices planning on p. 20-21.

Regards,

Kleanthis

dynamox · Answer

Ok, my sysadmins were trying to install RedHat to 2mb ACLX device ☺

dynamox · Answer

do you have ACLX device mapped to all of your FAs ?

RobertDudley · Answer

No the ACLX device is not mapped to any front end port.

RobertDudley · Answer

Yeah the funny things those admins do because they know better than we do.

Zikas · Answer

Hi Robert, are you using multipathing software?

If yes, did you try to mask it only to one path first?

How did you implement the lun offset?

Did you use the DLA (dynamic Lun Addressing)?

DLA allows for Symmetrix devices, regardless of their LUN address on the front-end director, to start at address 0 for a given HBA and director port pairing. In addition, DLA can be used to directly specify a LUN address for a given device. The Symmetrix V-MAX, with the use of Auto-provisioning Groups, not only automates director LUN mapping but also utilizes DLA to simplify LUN addressing.

Zikas · Answer

Also Robert, did you execute EMCGrab for that hosts? Did you check the HBA BIOS is at the EMC recommended level?

RobertDudley · Answer

We are using the masking view feature that defaults the first lun to 0 not lun offset as this is a VMAX not a DMX4.  You cannot run an EMCGrab on a host with no operating system as this is a boot from SAN environment and the host operating system is not yet installed.

dynamox · Answer

How do you run emcgrab if OS is not installed ?

SanjeevMalhotra · Answer

Also can you verify by presenting your boot lun to another Host as a data disk and check in diskpart if it shows Read-Only or Read-Write on the other host before presenting it to the Host in question in boot from SAN environment?

Also Reduce the server to a single path before attemptiong to boot from that LUN.

SanjeevMalhotra · Answer

EMC Primus emc250023 'Troubleshooting Configuration issues and OS installation issues in Boot from SAN environment' also identifies this issue, however it is not mentioned what causes it to go read only. I am assuming since this happens even before the OS is installed on the LUN 0, it shold be the HBA Driver/FW version which may be causing this issue. Did you verify that you have the latest version of the HBA driver/FW installed?

RobertDudley · Answer

Thanks for the primus solution. Doesnt answer the question but its definitely good information.

once we clear the read-only and install the operating system everything works fine. Its just on the initial install that lun 0 is viewed incorrectly.

Zikas · Answer

Good morning Robert,

sorry my mistake, i understood that you managed to install the O.S. from what you are saying: If we only present just a lun 0 it is not marked read-only;

So, you can execute from ELAB to check your configuration. You have to verify the HBA driver and FirmWare.

Also i suggested to deactivated the one path and to provision the LUN only from one path and to observe the behavior.

Did you do that?

sauravrohilla · Answer

I agree with Sanjeev Malhotra, it could be something to do with HBA drivers. Sanjeev, do you remember we had somewhat similar issue in Clariion where the server would not boot up if we present a thin boot lun along with other data luns and if we just present a thin boot lun, the server boots up fine?

regards,

Saurabh Rohilla

VMAX

Microsoft boot from SAN lun 0 read-only attribute

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