Patent ID: 7281158

Claim:
A method for data access comprising: grouping a plurality of disk drives into at least two disk groups, at least one disk group comprising disk drives configured as a redundant array, wherein one of said disk groups is not configured as a redundant array; organizing each disk group into one or more logical volumes, each said one or more logical volumes comprising two or more disk drives of one of said disk groups, a first logical volume among said disk groups being a primary volume, others of said one or more logical volumes being one or more secondary volumes, wherein data written to said primary volume is also written to said secondary volumes such that data in said primary volume is mirrored in said secondary volumes; and if said primary volume becomes unavailable, then designating one of said secondary volumes as a failover primary volume, including identifying said disk group to which said primary volume belongs and eliminating secondary volumes located on said disk group as candidates for said failover primary volume, wherein data is subsequently written to said failover primary volume.