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VCM disk showing up on SAN attached host
I just noticed this and seem strange to me: some hosts that SAN attached
see the VCM disk, even the disk is not masked on the directer port.
Enviroroment: EMC DMX 1000 ( Mcode 5670 ) and DMX3000 ( Mcode 5671).
hostA have solution enabler installed. while hostB did not.
I have two questions:
1. on hostA
hostA>#symdev -sid xxxx list | grep VCM
0000 c2t5006048ACAFE1E6Cd0* 13C:1 16A:D0 2-Way Mir N/Grp'd VCM WD 45
so device "0000" which is a VCM disk see hostA see as "c2t5006048ACAFE1E6Cd0" .
hostA>#echo |format | grep -i e6cd0
c2t5006048ACAFE1E6Cd0: configured with capacity of 44.06MB
2. c2t5006048ACAFE1E6Cd0
hostA>#symmaskdb -sid xxxx -dev 0000 list assignment
No device masking database records could be found for the specified input parameters
so why does lun "0000" showing up at all on hostA? does this have
anything to do with solution enalber?
2. on hostB, that DOES NOT have solutions enabler,
it also see the VCM disk ,and even worse, one of my SA's trying to
format and label the disk and unable to do that ( lucky we :- ).
so the question is: why can't format and label the VCM disk ?
is that because the state is WD ( write disabled )? and why
the VCM even showing up on this host?
Thanks.
JasonJ
see the VCM disk, even the disk is not masked on the directer port.
Enviroroment: EMC DMX 1000 ( Mcode 5670 ) and DMX3000 ( Mcode 5671).
hostA have solution enabler installed. while hostB did not.
I have two questions:
1. on hostA
hostA>#symdev -sid xxxx list | grep VCM
0000 c2t5006048ACAFE1E6Cd0* 13C:1 16A:D0 2-Way Mir N/Grp'd VCM WD 45
so device "0000" which is a VCM disk see hostA see as "c2t5006048ACAFE1E6Cd0" .
hostA>#echo |format | grep -i e6cd0
c2t5006048ACAFE1E6Cd0: configured with capacity of 44.06MB
2. c2t5006048ACAFE1E6Cd0
hostA>#symmaskdb -sid xxxx -dev 0000 list assignment
No device masking database records could be found for the specified input parameters
so why does lun "0000" showing up at all on hostA? does this have
anything to do with solution enalber?
2. on hostB, that DOES NOT have solutions enabler,
it also see the VCM disk ,and even worse, one of my SA's trying to
format and label the disk and unable to do that ( lucky we :- ).
so the question is: why can't format and label the VCM disk ?
is that because the state is WD ( write disabled )? and why
the VCM even showing up on this host?
Thanks.
JasonJ
xe2sdc
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February 12th, 2008 14:00
The VCM is WD just to avoid SysAdmins to mess your vcmdb
xe2sdc
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February 12th, 2008 12:00
The VCM is a very special volume that is always available even if no explicit masking exists. It's enough to map the volume with the VCM flag and all the hosts zoned to the FAs will see this very special volume.
In good old DMX (DMX1 and DMX2) the VCM is still a volume (24, 48 or 96 cyls big) whith another very important role: it contains the symmask database itself .. Since it contains such an important database, it's kept Write Disabled just to be sure that nobody will tamper it.
In new DMX (DMX3 and DMX4) the database is in another area (SFS - Symmetrix File System) of the storage and you don't really need a volume where to put the database. But you still need a volume always visible. So the flag VCM still exists and is usually assigned to a GateKeeper that's mapped to all the ports of the DMX.
Just to return in topic .. It's normal to see the VCM device even if no masking exists. Solution Enabler is our software that allows you to manipulate VCM and masking .. But you don't need S.E. to "see" the VCM .. From your message I can tell you that you have a DMX1 or DMX2 (models ranges from 800 to 3000) since the VCM is still WD (while with newer boxes it's RW enabled since it's a GK). Now you know why it's WD
Cheers !!
jasonj1
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February 12th, 2008 12:00
is even need to be visiable on the host side?
my reasoning is that VCM database is checked by the FA directors to see which host have accesx to which LUNx on that FA, so it is fine to allow FA have accees to VCM disk, but why the host need access it anyway?
Thanks.
JasonJ
jasonj1
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February 12th, 2008 13:00
what is confusing is at least in our enviroment that contains DMX1000( Mcode=5670) and DMX3000(Mcode=5671) , some hosts see the VCM disk,
some host don't. ( as checked via format ). any suggestions about why? would this maybe depending on solaris versions and/or HBA drivers ?
adding to the confusion is when the host does see the VCM disk, user or SA's will try to use this disk when they shouldn't.
Thanks for clarifying for me.
JasonJ
xe2sdc
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February 12th, 2008 13:00
Message was edited by:
Stefano Del Corno
jasonj1
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February 13th, 2008 08:00
to clarify on the "Write Disabled" flag: does it means:
Write disabled for host, but still RW for DMX and FA directors?
Thanks.
xe2sdc
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February 13th, 2008 10:00
amrith
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February 27th, 2008 22:00
We have a AIX 5.3 OS and we decommisoned DMX luns from this server.Even I removed the zoning.
The User DOESNT WANT TO SEE the VCM 0000 lun when he runs the inq command.
Can you tell me how to disappear this lun ?
xe2sdc
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February 27th, 2008 23:00
Do u want me to remove the fibre cables ! lol ..
Since your host is a betrayer, it's a good idea to unplug all the fibres
If you really can see the VCM from our DMX, that means you still have at least a zone that goes from one of your HBA to an FA .. that's it.
amrith
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February 27th, 2008 23:00
Do u want me to remove the fibre cables ! lol ..
What might be wrong here ?
xe2sdc
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February 27th, 2008 23:00
The VCM itself can not be hidden since you can't either "grant" or remove grant to an host. The VCM can be seen as long as the zoning is right. If you still can see the VCM (and you can show with the good old "dd" command its content) it's likely that the host still have zones
amrith
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February 28th, 2008 00:00
Anyways,I have asked the user to ignore this disk
xe2sdc
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February 28th, 2008 00:00
Did you reboot the host after removing the zones going to the DMX ??
Usually switches do implement the so called "soft zoning" .. Google a little to find better details, however to keep things short, it's a zoning implemented in the Name Service that the switches do always offer. You simply define a list of wwns that can talk one to each other (a zone). When the HBA logs into the fabric, it will ask the Name Service "Who can I talk to, today?" And the NS will answer supplying the list you configured. But if you later change the zoning (in the NS) and the host doesn't ask again "Who can I talk to?" nothing will stop it from sending frames to previously allowed destinations.
Since you are absolutly sure that there is no active zone going from your host to the DMX and you are also absolutly sure that you can still see the VCM, the only idea that comes to my mind is that you are using the so called "soft zoning" (that's the default on almost every switch) and your host didn't log out and in again on the fabric.
If possible, try to reboot the host .. and hope it does work
amrith
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February 28th, 2008 01:00
And hey I asked this query after rebooting the host !
xe2sdc
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February 28th, 2008 02:00
1) syminq | grep -i emc
2) symmask list hba
3) sympd list
ThX