From: JEDIDIAH on
On 2010-03-30, Arno <me(a)privacy.net> wrote:
>
>
> In comp.sys.ibm.pc.hardware.storage Yousuf Khan <bbbl67(a)spammenot.yahoo.com> wrote:
>> Arno wrote:
>>> Maybe Windows thinks that you cannot possibly want to span on
>>> removable devices? It has this habit of thinking it knows
>>> what you do and do not want but at the same time is far too
>>> stupid to pull it off.
>
>> Yeah, it looks like the case here. The technote says Microsoft doesn't
>> support this on USB or Firewire drives.
>
> Well, it does make some sense. Personally, I think the idea
> of "removable" devices is fundamentally flawed, and mounting and
> umounting as in Linux/unix is the far better approach. Bit apparently
> MS customers just yank out devices if it is mechanically possible.
> That could be a deisaster if the devices are RAIDed/

Any good RAID setup is going to have removable devices. That's kind
of part of the point of the whole thing. So the fact that you can
disconnect a USB drive isn't a terribly distinctive thing here. It really
shouldn't matter.

[deletia]

--
Apple: because TRANS.TBL is an mp3 file. It really is! |||
/ | \
From: Yousuf Khan on
Char Jackson wrote:
> Was my suggestion (RAID controller versus USB controller) considered?


The problem with putting the drives through a RAID controller is that
I'd have to bring these drives into the computer case and and connect
them permanently. I am trying to keep them as backup drives, therefore
they need to remain in the external case.
From: Yousuf Khan on
JEDIDIAH wrote:
> Any good RAID setup is going to have removable devices. That's kind
> of part of the point of the whole thing. So the fact that you can
> disconnect a USB drive isn't a terribly distinctive thing here. It really
> shouldn't matter.


Well, they don't want the drives to be *that* removable. There's a
difference between being swappable and portable. USB drives would be
considered portable.

Yousuf Khan
From: Arno on
In comp.sys.ibm.pc.hardware.storage Yousuf Khan <bbbl67(a)spammenot.yahoo.com> wrote:
> Arno wrote:
>> In comp.sys.ibm.pc.hardware.storage Yousuf Khan <bbbl67(a)spammenot.yahoo.com> wrote:
>>> Arno wrote:
>>>> Maybe Windows thinks that you cannot possibly want to span on
>>>> removable devices? It has this habit of thinking it knows
>>>> what you do and do not want but at the same time is far too
>>>> stupid to pull it off.
>>
>>> Yeah, it looks like the case here. The technote says Microsoft doesn't
>>> support this on USB or Firewire drives.
>>
>> Well, it does make some sense. Personally, I think the idea
>> of "removable" devices is fundamentally flawed, and mounting and
>> umounting as in Linux/unix is the far better approach. Bit apparently
>> MS customers just yank out devices if it is mechanically possible.
>> That could be a deisaster if the devices are RAIDed/
>>
>>
>>>> Incidentially the 800GB seems to be a problem with the enclosure,
>>>> there is no limit (that I know of) at 39.5 bit adress length.
>>>> Maybe give this pice of trash back?
>>
>>> Is it possible that there is a BIOS limitation, beyond 2TB? The
>>> motherboard I'm using is a rather plain desktop mobo, it may not be
>>> expecting such huge devices to join in?
>>
>> USB does not go over the BIOS, at least not in Linux. 2TB is 41
>> bit. No limit on byte level I can see. Number of sectors would
>> be 32. Ah, I think I see the problem. USB is using the storage
>> SCSI command set. It has either 32 bit or 64 bit for the sector
>> number. If the enclosure is resonably current, it should
>> support 64 bit sector numbers. Linux need compiled in kernel
>> support for large block devices to be able to handle block
>> devices > 2TB. This support has been there for some years, but
>> may be missing from your kernel. The config option is
>> CONFIG_LBDAF and found under "enable block layer" in 2.6.32.

> I asked the same question to Janos Mathe, the developer of HD Sentinel,
> he believes that the USB-SATA chipset is to blame here. These are his words:

>> It seems it is an overflow issue in addressing.
>> I'm sure it is not related to BIOS as the BIOS would only cause troubles
>> on disks which are under its control (for example if they were connected
>> to the motherboard and you'd try to boot from it). USB devices are controlled by the USB drivers of the OSes (Windows/Linux).
>>
>> I suspect the problem is related to the JMicron USB-ATA bridge which
>> translates the USB packets to ATA commands sent to the SATA drives.
>> I quickly checked the specs of this chip at http://www.jmicron.com/PDF/JM20336/JM20336.pdf
>> but as I see, JMicron do not mention the maximum drive capacity to be used.
>> However, I think at the time of release (2005) they were not prepared
>> for such BIG concatenated array and that's why the LBA addressing wraps around over 2 TB.
>> If I can help, please let me know.

> So it looks like there may be nothing that can be done here.

> Yousuf Khan

Hmm. Could be right. Missing large block device support in Linux
should not make it show up as smaller, just prevent it from being
used in its full capacity. Seems indeed that you are out of luck.

Arno
--
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno(a)wagner.name
GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
----
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans
From: Robert Nichols on
On 03/31/2010 04:04 PM, Yousuf Khan wrote:
> JEDIDIAH wrote:
>> Any good RAID setup is going to have removable devices. That's kind
>> of part of the point of the whole thing. So the fact that you can
>> disconnect a USB drive isn't a terribly distinctive thing here. It really
>> shouldn't matter.
>
>
> Well, they don't want the drives to be *that* removable. There's a
> difference between being swappable and portable. USB drives would be
> considered portable.

Indeed! The SATA connector is rated for a life of just 50 insertions.
You will run into that pretty quickly if you're swapping backup drives
around.

--
Bob Nichols AT comcast.net I am "RNichols42"