LUN Presentation Post: 302632047

Sponsored Content

Operating Systems Linux Red Hat LUN Presentation Post 302632047 by mark54g on Saturday 28th of April 2012 11:28:25 PM

04-29-2012

Registered User

If you have a /dev/dm device, you HAVE presented the LUN. This is the multipath daemon's way of abstracting the multiple paths as one device.

That way, assuming you had /dev/sdb, sdc, sdd, sde as 4 paths to the same disk, you would use /dev/dm-0 as the path you choose, and if you lose /dev/sdc then you still have 3 active paths and no loss in access, but perhaps performance

(Besides, an EVA only allows access via one controller at a time until a failure causes it to switch controllers. It's really the "Speak and Spell" of SAN technology)

In the Command View EVA tool you present the device to the WWN(s) of the host (You did properly zone the switch, correct?)

After that, you should follow the instructions on this page:

Scan and Configure New LUNS on Redhat Linux (RHEL)

If you are using native multipathing, run multipath -ll

Make sure the system sees all the paths. You can also create a disk lable with e2label (That way, when you run blkid, you can see which devices correspond to which path, etc without multipath -ll)

Tutorial: e2label, fdisk, /etc/fstab, mount, linux rescue, rescue disk, CentOS should help you there.

mark54g

View Public Profile for mark54g

Find all posts by mark54g

4 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

format date/time presentation

1) i am trying to print the timeframe of a log file using the start/end date/time being extracted from the file itself. my problem is how to convert the following numeric date format to the one that i prefer: Start time: 0204161129 End time : 0204171431 into: Start time: Apr 16 2002...

2. Solaris

I have LUN ID, how to find disk relate to that LUN ID?

I have a list of LUN ID, my task is to find if disk has been added or not. How do I do that? I have been searching the forum and not able to find answer. thanks

3. OS X (Apple)

Wireless presentation system for mac

I am a system developer for a major university and currently trying to find out WPS software for mac that can connect a mac to a wireless projector server. The software functions with Win OS XP and 7. The server is a EDIMAX WP-S1100 WIRELESS PROJECTOR SERVER.

4. Shell Programming and Scripting

Logs Presentation

Hello All, I am trying to capture system logs for specific tools run by users. So my script create logs from 10 different server.So is there any script & tool from that i can read or present them easily ?. Regards Ankit

LEARN ABOUT HPUX

vxdmp

vxdmp(7)						 Miscellaneous Information Manual						  vxdmp(7)

NAME

       vxdmp - Veritas Volume Manager multipathing disk devices

DESCRIPTION

       Multipathed  disk  devices  in Veritas Volume Manager (VxVM) represent virtual devices with one or more physical access paths to a physical
       disk.  The Multipathing feature provides disk access reliability by dynamically switching to another physical path if there is a path fail-
       ure.

       Every disk that is visible to VxVM is represented by a multipath device node in the /dev/vx/dmp and /dev/vx/rdmp directories for block type
       and character type interfaces.  A simple disk is represented by a multipath device having one physical path, whereas a disk that is part of
       a multiported disk array is represented by a multipath device with many device access paths depending upon the type of the disk array.

       VxVM  uses  standard  disk  device  naming conventions to name multipath devices.  For example, if there is a disk device with two physical
       access paths such as c1t0d0 and c2t0d0, the multipathing device node for this particular disk is created under /dev/vx/dmp and /dev/vx/rdmp
       as c1t0d0 or c2t0d0.

       To  provide  multipathing,  VxVM  maintains an internal database of all the multipathed devices detected by the system and their respective
       paths.  The database is created at system boot time.  When disks are added or removed from the system, VxVM provides support to reconfigure
       the multipath device database to reflect new states of the hardware, while the system is online.

       To reconfigure the DMP database, run ioscan followed by insf, and then invoke vxdctl enable (see vxdctl(1M)).

       The  various  access  paths to a multipathed device can be seen by using a vxdisk command (see vxdisk(1M)).  These commands open the multi-
       pathing configuration device /dev/vx/dmpconfig to obtain the required information about the various paths to a multipathed device and their
       states.

       VxVM also provides the facility to enable or disable a disk controller. This feature can be used to stop all I/Os through a particular con-
       troller to perform maintenance operations on it.  Use the vxdmpadm command to do this and also perform other operations	on  the  multipath
       device database.

       VxVM  can  provide notification about events that occur in the DMP database due to a change in hardware.  See the vxnotify(1M) man page for
       more information.

       VxVM is capable of multipathing both Active/Active and Active/Passive disk arrays.

FILES

       /dev/vx/dmp		     Multipathing block devices.

       /dev/vx/rdmp		     Multipathing character devices.

SEE ALSO

       ioctl(2), vxdctl(1M), vxdisk(1M), vxdmpadm(1M), vxnotify(1M)

VxVM 5.0.31.1							    24 Mar 2008 							  vxdmp(7)