The family story my mum was told was that the name was Spanish. Another researcher told me that they had been told the same thing, and that it was from an Armada ship wrecked somewhere near the mouth of the Mersey. The name then spread up river - Runcorn, Warrington, Salford, then across into west Yorkshire.
The trouble is that it's probably as reliable as the rest of the stories my mum was told. Her grandfather turns out not to have been the 7th son of a 7th son, though the warts were charmed away in any case. Her Marsh ancestors were supposed to descend from local lad George Marsh - St. George the Martyr - with every generation containing a George in his honour. So far I've found only ONE George!
My gut feel is that the name will eventually turn out to be a variation of the irish surname Donovan.
My ggg grandfather James Johnson Donbavand was literate; he signed his marriage certificate very confidently in 1852, and the spelling of his name is consistent all through the army pay books.
My troubles are that I don't know where JJD came from - I have no censuses with him on - and I've no idea where his family were while JJD was in the army. They are missing from two censuses. JJD joined up a couple of weeks before his son James was born in Bolton. The next record I have of anyone in the family is the marriage, in Bolton, of James junior, now with a middle name of Johnson to match his dad. He then settles down as a paper maker, the same trade as his mother's family. So where were JJD's wife and two children while he was serving in India? It seems unlikely that they would follow him there, since he arrived at the end of the Indian Mutiny, but they may have gone to the area around the Depot of the regiment, which by some wierd circumstance was in Co. Cork.