• Well, the mirror has to have writes to affect the changes brought over from the tlog on the primary so I would expect actual writes to be higher than the shipped volume. As for disk busy metrics, perhaps the mirror secondary hardware isn't as good as the primary - or has other activity on it?

    Best,
    Kevin G. Boles
    SQL Server Consultant
    SQL MVP 2007-2012
    TheSQLGuru on googles mail service