Increase/decrease of EMC Symmetrix BCV mirror sets to provide additonal copies of data

[Will Sterling]

Can anyone tell me if it is possible to increase and decrease the mirror levels of EMC Symmetrix BCV devices to provide additional copies of data?

What I would like to do is have 3 BCV volumes but since I can only have one BCV for any standard what I am thinking of doing is making my BCV devices three way mirrors before they are synced to their standard devices. Then reducing the BCVs to having 0 mirrors. The EMC documentation states that the mirrors will then be new devices.

I'm uncertain to if this process is repeated regularly will the mirrors always be assigned to the same device name/HP-UX special device files.

[Sivakumar MJ._1 · Accepted solution]

Hi,

You can have upto 8 BCV to a standard volume but not at the same time.

You can have only two BCV attached to a standard volume and u can have 8 clone attached to the standard volume at the same time,
again there are two types of BCV's protected BCV and unprotected BCV as any standard device will have four mirror positions

1. first mirror position is the device itself

2. second mirror position is taken by RAID
so a typical SYMM. device wil always use two mirror positions one for the device and second for the raid device(mirror)
you cannot break this and use them as two seperate devices with that said two out of four is always used by any SYMM. device
the remaining two mirror positions can be used for two purposes

a. we can have a local BCV device attached to it in which case its 2 BCV max at the same time -- because only two mirror positions are available

b. we can have an SRDF device in remote SYMM. two different symmetrix
that is concurrent srdf

3. we can have one BCV and one SRDF - one local copy and one remote copy there are the combinations available there is a fourth type called CLONE which will not use the mirror position so we can clone a standard device into 8 clones to 16 clones at a time without sacrificing any mirror positions.

we cannot have 3 BCV's for a standard device
because symmetrix does not support unprotected standard device