Re: Reading HFS Standard Block0 on USB thumb drives
Re: Reading HFS Standard Block0 on USB thumb drives
- Subject: Re: Reading HFS Standard Block0 on USB thumb drives
- From: Aaron Burghardt <email@hidden>
- Date: Mon, 30 Jan 2012 08:58:35 -0500
Is this still an issue for you?
Mac OS X supports mounting disks that have no partition map and the entire media is dedicated to a file system, although the system normally creates a partition map. In the case of HFS and HFS+, the volume header starts 1024 bytes into the partition (i.e., the third sector on a typical 512-bytes-per-sector hard disk), so try reading the first few blocks to confirm.
Also, you can use Disk Utility to Get Info on the mounted partition to see which device is mounted. Disk Utility will show you the whole media object (which shows the partition map, if it exists) and the partitions on that media.
Aaron
On Jan 13, 2012, at 9:56 PM, Mike wrote:
> Thanks Alison,
>
> I tried it on the device in question and it shows 512 bytes of zeros.
>
> Is your device HFS+ formatted or HFS? I am trying to read HFS only (as described in the old IM: Devices SCSI Manager chapter).
>
> I noticed 'diskUtil list' in Terminal shows that it doesn't recognize the partition format, yet the 10.6.8 Finder can mount it as read-only just fine and I see my files on it I copied over from when I formatted it with Drive Setup on OS 9:
>
> /dev/disk0
> #: TYPE NAME SIZE IDENTIFIER
> 0: GUID_partition_scheme *1.0 TB disk0
> 1: EFI 209.7 MB disk0s1
> 2: Apple_HFS 10.6 569.4 GB disk0s2
> 3: Apple_HFS Files 269.3 GB disk0s3
> 4: Apple_HFS Applications 100.8 GB disk0s4
> 5: Apple_HFS 10.6 FCP X 51.3 GB disk0s5
> /dev/disk1
> #: TYPE NAME SIZE IDENTIFIER
> 0: GUID_partition_scheme *80.0 GB disk1
> 1: EFI 209.7 MB disk1s1
> 2: Apple_HFS Files FireWire 79.7 GB disk1s2
> /dev/disk3
> #: TYPE NAME SIZE IDENTIFIER
> 0: untitled *2.0 GB disk3
>
> I know it's formatted correctly because I can see and access the files on it from Finder.
>
> Thanks,
>
> On 1/13/12 7:49 PM, Alison Cassidy wrote:
>> I'm no expert, but have you tried running something like 'dd if=/dev/rdisk1 bs=512 count=1 | xxd' from the command-line? I just tried this on an old APM-formatted drive I have here and everything looks okay ....
>>
>> -- Allie
>>
>> On Jan 13, 2012, at 6:39 PM, Mike wrote:
>>
>>> > Hi,
>>> >
>>> > I am trying to read a Block0 driver descriptor map from old-style Apple Partition Map formatted USB thumb drives which were formatted using Mac OS Standard (HFS) on OS 9. I am using Xcode 4.2 on 10.6.8.
>>> >
>>> > But when I do the read the entire Block0 structure comes back filled with zeros. I've checked my device open and seek calls and they correctly set to byte offset 0 on the device.
>>> >
>>> > Any idea why this is happening?
>>> >
>>> > Thanks,
>
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