"Online piecemeal restore scenario
In an online piecemeal restore, after the partial-restore sequence, the database is online, and the primary filegroup and any recovered secondary filegroups are available. Filegroups that have not yet been restored remain offline, but they can be restored as needed while the database remains online.
Online piecemeal restores can involve deferred transactions. When only a subset of filegroups has been restored, transactions in the database that depend on online filegroups might become deferred. This is typical, because the whole database must be consistent. For more information, see Deferred Transactions."
attenzione, perchè la parola corretta è offline
.Ho già contattato per la risoluzione del problema e in breve tempo avremo la correzione.
Condivido questo perchè potrebbe essere utile non cascare nell'inganno 
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Stay tuned! 