External USB drive size limit

  • Thread starter Thread starter CWatters
  • Start date Start date
C

CWatters

Are there any limits (apart from thermal/power) to the capacity of drive you
can put in a USB 2.0 drive enclosure? If this is chipset specific... I'm
looking at an enclosure that uses the "Cypress AT2 Plus".

Thanks
 
Previously CWatters said:
Are there any limits (apart from thermal/power) to the capacity of drive you
can put in a USB 2.0 drive enclosure? If this is chipset specific... I'm
looking at an enclosure that uses the "Cypress AT2 Plus".
Click to expand...

The command set used is the SCSI storagecommand set. It allows
32 bit secotr numbers, giving you 2.1TB per device with 512
Byte sectors. Still a bit until disks reach that size and
there was talk about increasing sector sieze recently.

If I remember correctly, there ia also an option for 64 bit
sector numbers, but I don't know whether that is used in USB.

On the chipset side, if it is an SATA disk, then you
usually have 48 bit secor numbers (LBA) and hence no
practical limitation. If it is an IDE disk, then you
can have a limitation and yes, it is chipset specific.

Have you looked on the vendor/manufaturer website of the
enclosure?

Arno
 
Arno Wagner said:
The command set used is the SCSI storagecommand set. It allows
32 bit secotr numbers, giving you 2.1TB per device with 512
Byte sectors. Still a bit until disks reach that size and
there was talk about increasing sector sieze recently.

If I remember correctly, there ia also an option for 64 bit
sector numbers, but I don't know whether that is used in USB.

On the chipset side, if it is an SATA disk, then you
usually have 48 bit secor numbers (LBA) and hence no
practical limitation. If it is an IDE disk, then you
can have a limitation and yes, it is chipset specific.

Have you looked on the vendor/manufaturer website of the
enclosure?

Arno
Click to expand...

Thanks for that.

The enclosure takes several parallel ATA drives. I couldn't see anything on
the makers web site for this model - have sent them email.
 
Typical question that only comes up if you already know the answer.
Still a bit until disks reach that size
Click to expand...

How about today with 4 500GB drives.
and there was talk about increasing sector sieze recently.
Click to expand...

Physical, not logical.

Which has got nothing to do with SATA at all other than that it may
be a more recent chipset that is likelier to not have such a limitation.

If the chipset in the USB2 box is parallel with a parallel to serial conver-
ter added for SATA then you have the same chance of having that limitation.

Thanks for yet another of your clueless rants, babble mouth.
 
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