TiVo Community Forums Archives - forcing only 120GB on a 160GB drive

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forcing only 120GB on a 160GB drive
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Posted by: dmbong

Anybody have some relatively straight forward steps for doing this?

I was thinking of just moving my backup onto the 160 then expanding it but expanding it ONLY as far as would be usable for later replacing the 160 with a 120.

Any clues?

Thanks!

-Brian

Posted by: HTH

AFAIK, there are no tools yet that can let you have them pretend a drive has a smaller arbitrary capacity than reality.

Another problem is knowing the size of the future 120 GB drive precisely. You'd probably have to low-ball its capacity (119.9 GB) when simulating it on the larger drive.

Posted by: DavidO

There is a firmware command that allows this. It's documented in the ATA specs (www.t13.org)

The commands are: Device Configuration Identify & Device Configuration Set.

The new capacity (in sectors) would be placed at offset 6, and compute a checksum.

The Maxtor drive should support this command, although I haven't tried it. WD drives do, but there isn't (yet) a WD drive > 120 GB, anyway.

By the way, if anyone were to do this, I'd suggest 137 GB, not 120 GB.

Posted by: dmbong

David...that's cool enough, but, I don't think there ends up being a need to do it on the 160's and set it at 137...also, I don't need to do it in firmware, as I am only trying to keep it at 120GB in order to replae the 160 with a 120. If I set it to 137, that'd blow the point of it. I only want to use 120GB of the 160 so that I can replace it with an actual 120. I was thinking there might be some way to get BlessTiVo or some other util to only allocate so much space on the drive so as not to hit 137GB.

-Brian

quote:
Originally posted by DavidO
There is a firmware command that allows this. It's documented in the ATA specs (www.t13.org)

The commands are: Device Configuration Identify & Device Configuration Set.

The new capacity (in sectors) would be placed at offset 6, and compute a checksum.

The Maxtor drive should support this command, although I haven't tried it. WD drives do, but there isn't (yet) a WD drive > 120 GB, anyway.

By the way, if anyone were to do this, I'd suggest 137 GB, not 120 GB.

Posted by: DavidO

Yeah, the Device Configuration is designed to do just this type of thing - change the "reported" capacity of the drive (or change the "reported" UDMA setting.

So, set the drive to 120 GB, boot up with the Linux TivoMad, it will see it as 120 GB and you can bless it at that capacity. You can then reset (via Device Configuration Restore) it back to 160.

Posted by: Otto

Maybe I'm missing something..

If you hook the 160 gig drive to an older controller that uses 28 bit addressing only, won't it only see the 128GB? Then you could just bless and go, yeah?

EDIT: Oh. I get it.. you want to copy the thing to a 120 later.. Never mind.

Posted by: dmbong

Hey, that's a cool idea. Not familiar with how to change those settings. Are they available in the Powermax Utils?

-Brian

quote:
Originally posted by DavidO
Yeah, the Device Configuration is designed to do just this type of thing - change the "reported" capacity of the drive (or change the "reported" UDMA setting.

So, set the drive to 120 GB, boot up with the Linux TivoMad, it will see it as 120 GB and you can bless it at that capacity. You can then reset (via Device Configuration Restore) it back to 160.