Ata Bohra proposed a backend concept for the ESX storage driver to simplify the addition of iSCSI support to the ESX storage driver. The problem here is that most of the storage driver functions need to determine the backend to be used from the pool name. This overhead can be avoided by adding a private data pointer to the virStoragePool and virStorageVol structs that the ESX storage driver can use to store a pointer to the correct backend. struct _virStoragePool { virObject object; virConnectPtr conn; char *name; unsigned char uuid[VIR_UUID_BUFLEN]; void *privateData; virFreeCallback privateDataFreeFunc; }; struct _virStorageVol { virObject object; virConnectPtr conn; char *pool; char *name; char *key; void *privateData; virFreeCallback privateDataFreeFunc; }; virGetStoragePool and virGetStorageVol would set privateData and privateDataFreeFunc as given by the caller. virStoragePoolDispose and virStorageVolDispose would call privateDataFreeFunc if set. Comments?