device configuration and Mapping to the host

Question

Hi

Possible device configuration values in Symmetrix are

Unprotected
2-Way-Mir
3-Way-Mir
4-Way-Mir
RAID-S
RDF1
RDF2
RDF1+R-S or RDF1-R-S a
RDF2+R-S or RDF2-R-S a
RDF1+Mir or RDF1-Mir
RDF2+Mir or RDF2-Mir
BCV
2-Way-BCV-Mir
DRV
RDF1-BCV a
RDF2-BCV a
RDF1-BCV+Mir or RDF1-BCV-Mir a
RDF2-BCV+Mir or RDF2-BCV-Mir a
VDEV
RAID 5
BCV+R-5 or BCV-R-5
RDF1+R-5 or RDF1-R-5
RDF2+R-5 or RDF2-R-5
RDF1-BCV+R-5 or RDF1-BCV-R-5
RDF2-BCV+R-5 or RDF2-BCV-R-5

In the above configuration RDF2 cannot be mapped to a Host since it contains remote data of RDF1 in the particular symmetrix.

I am trying to find all symdevice which can be mapped to host. Can you please tell what all the device can be mapped to a host from a particular symmetix having the following device configuration. As of i know RAID-S, RDF1,RAID 5 etc.

In simple , I need from above possible device configuration, what all the devices can be mapped to host and devices cannot be mapped to the host.

Naren

xe2sdc · Accepted Answer

Any RDF2 device (while established to its corresponding R1 device) will be write disabled (as you noted).

Any BCV (BCV,2-Way-BCV-Mir,BCV+R-5) can be either writable (while splitted) or not_ready to the host (while synching from its corresponding source).

Never had the pleasure to work with RDF2-BCV devices. I guess it's simply a "temporary" configuration required while moving from A configuration to B configuration... I'd simply forget about them

SKT2 · Answer

'In the above configuration RDF2 cannot be mapped to a Host since it contains remote data of RDF1 in the particular symmetrix'Did u mean RDF2 is the GBCV( BCV from from R2) Or R2 itself?R2 and GBCV can be masked to a host(at least HP-UX) and we use vgcghdid b4 making use of either R1 or GBCV devices. But that may not possible with Windows/LINUX .

xe2sdc · Answer

From a pure storage point of view the only "unmappable" devices are:

* Unprotected (can be managed only via binfile change)
* DRV (used by Symmetrix Optimizer)

Again from a pure storage point of view you CAN map R2 devices (any R2 device) and present it to an host.
You can't use an R2 device from the host point of view (since it's usually write-disabled). But the storage won't forbid you from mapping any R2 device.

RRR · Answer

You can't use an R2 device from the host point of view (since it's usually write-disabled). You can read from the R2's ! The mapped R2's work like readonly disks.

xe2sdc · Answer

In my experience no host filesystem allows you to mount a filesystem that's changing.

If you mount a filesystem as "read only" the host will suppose the content isn't changing (a CD rom is read only). But the content of R2 device WILL change while Synch/Consistent.

I expect a lot of kernel crashes

RRR · Answer

On Windows on a relatively static data volume which you yourself control, you can use it And there's always the add/remove driveletter to reload the directory tables..... Worked fine for me

naren23-3_uew · Answer

Thanks for all your answers.Please confirm my assumptions below is correct.Cannot be Mapped to Host:================UnprotectedDRVMapped and Read-write:======================2-Way-Mir3-Way-Mir4-Way-MirRAID-SRDF1RDF1+R-S or RDF1-R-S aRDF1+Mir or RDF1-Mir2-Way-BCV-Mir - I don't know whether this configuration is writable or notRDF1-BCV aRDF1-BCV+Mir or RDF1-BCV-Mir aVDEVRAID 5RDF1+R-5 or RDF1-R-5RDF1-BCV+R-5 or RDF1-BCV-R-5Mapped and Read-only:========================RDF2RDF2+R-S or RDF2-R-S aRDF2+Mir or RDF2-MirBCVBCV+R-5 or BCV-R-5RDF2-BCV aRDF2-BCV+Mir or RDF2-BCV-Mir aRDF2+R-5 or RDF2-R-5RDF2-BCV+R-5 or RDF2-BCV-R-5

naren23-3_uew · Answer

Hi Stefano,I don't understand about the BCV devices. I know BCV devices are mirrored devices within in the same Symmetrix and it will be read-only when it is not split.When BCV devices got splitted then Device configuration won't change since it is no longer can act as BCV device(i.e Since it got split.).My Assumption is :So if Symdevice shows Device Configuration as BCV then it will be read-only and It can be writable by host until it gets splitted and device configuration will change when it gets splitted and not_ready to the host (while synching from its corresponding source).Please confirm

MikeMac1 · Answer

When a BCV is established to it's standard device, it takes on the standard devices device number. While it's established, the BCV's can not be read from or written to as if it is it's own device. Once a BCV is split, it takes back its device number and can be read from and written to as long as it's mapped to a host.

naren23-3_uew · Answer

What all the possible State of Pair,State of BCV Mirrors in symmetrix.

Sample output:

State of Pair ( STD <=\=> BCV ) : Split
Time of Last BCV Action : Tue Jan 13 04:40:23 2009

State of BCV Mirrors : Synchronized

BCV State Flags : (AllReady)
Percent Split : 100%

xe2sdc · Answer

I guess TimeFinder manuals may give you a list of available states.

Symmetrix

device configuration and Mapping to the host

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