• Split mirrors can also be used to create point-in-time copies of data
• Split mirrors are maintained using the same process as a standard RAID mirror set
• The mirroring process can be stopped and the split mirror volume can then be accessed by another server
Primary RAID Split Mirror
All in same array
Some enterprise subsystems also provide a type of mirror called a “split mirror”.
Unlike a standard mirror, the mirroring process for a split mirror can be stopped and restarted arbitrarily to split and resynchronize the mirror with the primary volume. Like snapshots, this allows users to create point-in-time copies of volumes.
Mirrors can also occur in the host using volume manager. Data would be written to both volumes during normal operation. Once a point in time copy is created and the mirror split, a write log is generated for all subsequent writes which is then used to restore the mirrored image once the mirror is resynchronized.
Split mirrors are called different names by different vendors (EMC – Business Continuance Volumes , HDS – ShadowImage, HP – Business Copy)
All the same thing, an extra copy of our data at a given point in time.