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Old 11-13-2007, 12:43 PM   #406
ravi26
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There used to be a single string bowed instrument played by wandering gypsies. You wouldn't think it capable of much...but in the hands of a master player it could move you to tears.

Didn't think you could do that with the "dd" tool. Will be working on trying out all those variations for a long time.....! Thanks for putting it out there...
 
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Old 11-15-2007, 12:07 AM   #407
chittra
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thank u. if it does not store wht we throw to it, can this command be considered as a read only operation?
 
Old 11-15-2007, 02:48 AM   #408
Tinkster
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Quote:
Originally Posted by chittra View Post
thank u. if it does not store wht we throw to it, can this command be considered as a read only operation?
If you write something on the surface of water, are
you reading?



Cheers,
Tink
 
Old 11-30-2007, 09:31 AM   #409
dive
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Is there some reason dd doesn't work with audio cds? I just bought 2 new Pioneer DVD-RW DVR-112Ds. I've tried a few cds but no go. Tested with a dvd and worked fine so it doesn't look like faulty drives (fingers crossed).

Code:
dd if=/dev/hdc of=cd.iso bs=2048 conv=notrunc
dd: reading `/dev/hdc': Input/output error
0+0 records in
0+0 records out
0 bytes (0 B) copied, 0.368429 s, 0.0 kB/s
 
Old 12-03-2007, 04:25 AM   #410
JZL240I-U
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Not really a pure dd-question, but...

Using lvm (lvm2, logical volume manager) I presume one still can copy physical volumes with dd, right? So how can one change the volume groupe to use the "new" or cloned volume, anybody with experience here or is this all a wrong assumption?

Last edited by JZL240I-U; 12-03-2007 at 05:28 AM.
 
Old 12-16-2007, 05:33 AM   #411
mso
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thank you very much~~ added into my bookmark
 
Old 12-18-2007, 01:24 PM   #412
AwesomeMachine
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Post CD vs DVD

Quote:
Originally Posted by dive View Post
Is there some reason dd doesn't work with audio cds? I just bought 2 new Pioneer DVD-RW DVR-112Ds. I've tried a few cds but no go. Tested with a dvd and worked fine so it doesn't look like faulty drives (fingers crossed).

Code:
dd if=/dev/hdc of=cd.iso bs=2048 conv=notrunc
dd: reading `/dev/hdc': Input/output error
0+0 records in
0+0 records out
0 bytes (0 B) copied, 0.368429 s, 0.0 kB/s
Music CDs are not data. There is no file system on a music CD. DVD movies are data. There is a file system on a DVD movie disk. Dd only works with file systems.
 
Old 12-18-2007, 01:34 PM   #413
AwesomeMachine
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LVM and dd

Quote:
Originally Posted by JZL240I-U View Post
Not really a pure dd-question, but...

Using lvm (lvm2, logical volume manager) I presume one still can copy physical volumes with dd, right? So how can one change the volume groupe to use the "new" or cloned volume, anybody with experience here or is this all a wrong assumption?
LVMs can use different partitions, even on different machines, as part of a single LVM. Dd will probably not work correctly with LVMs. I don't use LVMs, and I know a good number of people who refuse to use them, because standard UNIX tools won't work with them. But, LVMs are scalable. You can add a drive to an LVM with a few simple commands, giving the extra storage needed, without having to redo the whole system.
 
Old 12-18-2007, 01:36 PM   #414
AwesomeMachine
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Smile Hey New Guy

Quote:
Originally Posted by mso View Post
thank you very much~~ added into my bookmark
You're Welcome

-Awesome
 
Old 12-18-2007, 07:12 PM   #415
terryxela
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I posted in the wrong thread. I could not delete the message so I just erased as much as I could :-(
Have all of you Happy Hollidays!!

Last edited by terryxela; 12-20-2007 at 08:58 AM.
 
Old 12-19-2007, 02:07 AM   #416
JZL240I-U
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Quote:
Originally Posted by AwesomeMachine View Post
...Dd only works with file systems.
Umm.
Code:
dd if=/dev/urandom of=/dev/hdb
where /dev/hdb is a new disk won't work? I always thought that one could initialize a new disk that way but if you say that won't work...

Thanks for clarifying the LVM problem .

Oh, and I bookmarked this thread as well, thank you for your effort.

Last edited by JZL240I-U; 12-19-2007 at 02:08 AM.
 
Old 12-21-2007, 12:04 AM   #417
AwesomeMachine
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Post I should have been more specific.

Quote:
Originally Posted by JZL240I-U View Post
Umm.
Code:
dd if=/dev/urandom of=/dev/hdb
where /dev/hdb is a new disk won't work? I always thought that one could initialize a new disk that way but if you say that won't work...

Thanks for clarifying the LVM problem .

Oh, and I bookmarked this thread as well, thank you for your effort.
Dd only works with files and file systems, at least on the read end.
 
Old 12-22-2007, 06:06 PM   #418
lin_myworld
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Hey Awesome Post..
but getting prblem in understanding sectors,cylinders..in refernce to hard disk
can tell some material for reading.
thanks
 
Old 12-25-2007, 03:54 AM   #419
AwesomeMachine
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Smile Sectors Heads Cylinders

Quote:
Originally Posted by lin_myworld View Post
Hey Awesome Post..
but getting prblem in understanding sectors,cylinders..in refernce to hard disk
can tell some material for reading.
thanks
A HDD's heads all move together. If one head needs to go somewhere, all the rest have to come along. There is one head for each side of every platter in the drive. If there are three platters, there are six heads. When one head moves to a track to read or write, the other heads are above the same track, but on different platters, or on the other side of the same platter. These tracks together are a cylinder. They are exactly stacked.

LBA addressing makes every drive '63 sectors per track' * '255 heads' = '16065 sectors = 1 cylinder. 1 sector = 512 bytes.

No one uses actual Cylinder Head Sector geometry anymore, but there was a time when this information was necessary, and wasn't printed on the drive. Almost no one installed HDDs in those days, but if one attempted it, it was an all day project. Most of the time was spent on the phone to IBM's engineering department, because the only person who would know hard drive parameters was the one who designed it.

In those days, a huge HDD was 10 MB. A huge amount of memory was 64 KB. In fact, Bill Gates is quoted as saying, "64 K of memory? That's more than anyone could ever use."
 
Old 12-26-2007, 03:45 PM   #420
BT+1
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Quote:
Originally Posted by AwesomeMachine View Post
These tracks together are a cylinder. They are exactly stacked.
Not any more: each track has its own positioning information, and when you switch from one track to another on the same cylinder it incurs some settling time to position the heads exactly, unlike the situation with older, less dense disks when the heads were already exactly aligned over the new track because all tracks shared the same 'servo' track that handled positioning. Today, it doesn't take noticeably less time to switch to another track on the same cylinder than it takes to switch to a track on an adjacent cylinder.

Quote:
LBA addressing makes every drive '63 sectors per track' * '255 heads' = '16065 sectors = 1 cylinder. 1 sector = 512 bytes.
Not according to the definition which you presented above, which defined a *physical* cylinder. Your numbers above define a *logical* cylinder for use by obsolete software or firmware that doesn't understand LBA addressing and needs the disk to give it fictitious information in the old format to use to address data on the disk (e.g., some logical cylinders are defined to use only 240 heads to work around a quirk in some obsolete BIOS firmware - but neither logical definition has anything to do with the physical layout of data on the disk). A logical cylinder has no remaining significance with contemporary software/firmware, and the significance of a physical cylinder has dwindled since individual tracks started taking care of their own positioning information.

Quote:
No one uses actual Cylinder Head Sector geometry anymore, but there was a time when this information was necessary, and wasn't printed on the drive. Almost no one installed HDDs in those days, but if one attempted it, it was an all day project. Most of the time was spent on the phone to IBM's engineering department, because the only person who would know hard drive parameters was the one who designed it.
It wasn't necessarily *quite* that bad. I had occasion to reinstall such a drive a few years ago after the CMOS battery on the motherboard died and the settings were lost, and the required C/H/S information was still available on the Web.

Quote:
In fact, Bill Gates is quoted as saying, "64 K of memory? That's more than anyone could ever use."
The alleged quote was "640 K ought to be enough for anybody", and it was allegedly said in the context of what was useful *at the time he allegedly said it* (at a mid-1981 trade show) rather than as a statement for all time. Since (e.g.) DEC was still doing a brisk business in 16-bit minicomputers back then, many of which were limited to 256 KB of RAM (indeed, DEC's first personal computers based on this product line shared this limitation when they were introduced in 1982), the statement was not unreasonable in that context.
 
  


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