"b=512 skip=63"

[harcheng]

"b=32256 skip=1" seems to be faster than "b=512 skip=63", but will it work? I need to reinstall my OS x86. Also, before reinstalling, do I have to reformat the entire partition?

[jazzy639]

I was wondering the same thing - which one of the following 4 worked:

 

1. dd if=tiger-x86-flat.img of=\\.\PhysicalDrive# bs=1M

 

2. dd if=tiger-x86-flat.img of=\\.\PhysicalDrive#

 

3. dd if=tiger-x86-flat.img of=\\.\PhysicalDrive# bs=512 skip=63

 

4. dd if=tiger-x86-flat.img of=\\.\PhysicalDrive# bs=1048576

 

Thanks

[harcheng]

Hey it does work! I tried using "b=32256 skip=1" and it works (63x?) faster!

[qimtiger]

Yes,It works well,and after later,I can rebuild the tiger pation every easily.

 

And I advice after you dd to a pation and boot successfully,you should dd the tiger pathion to an image file in win.

 

Then,You can use bs=1M to restore the tiger partion later.

[wow]

Hey it does work! I tried using "b=32256 skip=1" and it works (63x?) faster!

<{POST_SNAPBACK}>

i know bs but not b

 

What does that mean and what means the skip part?

 

ps i used bs=1440k and it was done in 1 minute, it was so quick that i though it failed.

[TheElementWithin]

I used bs=512 skip=63 and it took about an hour, and I still havent actually got it working.

[jazzy639]

I used dd if=tiger-x86-flat.img of=\\.\PhysicalDrive# bs=1048576

and it worked perfectly!

[wow]

I used dd if=tiger-x86-flat.img of=\\.\PhysicalDrive# bs=1048576

and it worked perfectly!

<{POST_SNAPBACK}>

Hm how quick would bs=1T? :0 be

 

(T = Terra )

[silicontrip]

Hm how quick would bs=1T? :0  be

 

(T = Terra  )

<{POST_SNAPBACK}>

 

That would depend on the cache and maximum request size of your harddisk.

 

And the amount of memory in your machine, you'll need a terabyte of free memory available inorder to get it to work

[kidgoo]

If you are using a disk image, it is important to specify skip=63. This tells dd to ignore the first 63 bytes of the image, which happen to be the partition table information, and to only copy the partition itself. Most likely, if you put skip=1, you'll have junk at the start of the partition. The OS may be able to cope, but it's not a proper partition. The Disk Utility may be able to corrected it.

 

The skip parameter has nothing to do with speed. Keep it at 63 if you use the disk image.

 

btw, bs=* tells how many bytes to read and write at once. 512 is conservative and safe. Most people would be able to get by with 1M. Don't go too high or you'll run out of memory, or may get read/write errors.

 

All of this information is in the dd man page.

[youra]

If you are using a disk image, it is important to specify skip=63.  This tells dd to ignore the first 63 bytes of the image, which happen to be the partition table information, and to only copy the partition itself.  Most likely, if you put skip=1, you'll have junk at the start of the partition.  The OS may be able to cope, but it's not a proper partition.  The Disk Utility may be able to corrected it. 

 

The skip parameter has nothing to do with speed.  Keep it at 63 if you use the disk image.

 

btw, bs=* tells how many bytes to read and write at once.  512 is conservative and safe.  Most people would be able to get by with 1M.  Don't go too high or you'll run out of memory, or may get read/write errors.

 

All of this information is in the dd man page.

<{POST_SNAPBACK}>

You are wrong. Skip tells dd to ignore first 63 blocks of the specified by "bs=" size. You need to skip 63*512=32256 bytes. You can use "bs=32256 skip=1" which is much faster. So "bs=1M" will not work properly with windows version of dd. In Linux you can use ibs and obs parameters: "ibs=512 obs=1M skip=63"

[kidgoo]

You are wrong. Skip tells dd to ignore first 63 blocks of the specified by "bs=" size. You need to skip 63*512=32256 bytes. You can use "bs=32256 skip=1" which is much faster. So "bs=1M" will not work properly with windows version of dd. In Linux you can use ibs and obs parameters: "ibs=512 obs=1M skip=63"

<{POST_SNAPBACK}>

Ah yes....I see. That is correct. Didn't notice the bs=32256...only just woke up, and my brain is still trying to....

 

Sorry for spreading confusion!