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Re: USB: Logical Unit Is In Process Of Becoming Ready [was Re: USB umass hard drive "failed to create xfers" when attaching] (Thomas Klausner) writes:

>umass0: using SCSI over Bulk-Only
>scsibus0 at umass0: 2 targets, 1 lun per target
>sd0 at scsibus0 target 0 lun 0: <Samsung, D3 Station, 0202> disk fixed
>sd0(umass0:0:0:0):  Check Condition on CDB: 0x00 00 00 00 00 00
>    SENSE KEY:  Not Ready
>     ASC/ASCQ:  Logical Unit Is In Process Of Becoming Ready
>sd0: drive offline
>autoconfiguration error: sd0: unable to open device, error = 5

That's one of the design issues with wedges. A regular disk exists
even when "offline" and evaluating partitions can be deferred to
the time when it is opened by some process. Wedges are only created
when the device is online, which means you cannot open them to
trigger anything.

The only option is to poll an "offline" disk regularly to find out
when to retry the wedge creation. But this alone is of questionable
value because this state usually refers to removable media where
partitioning can easily change. So you also need to drop wedges
when you detect that the medium got ejected. This may require
polling as well, at least in otherwise idle periods.

                                Michael van Elst
                                "A potential Snark may lurk in every tree."

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