6 about hardware buffer size
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dd has many (weird) options, see dd(1).

You should explicitly state the buffer size, so try

dd if=/dev/sda of=/dev/sdb bs=16M

IIRC, the default buffer size is only 512 bytes. The command above sets it to 16 megabytes. You could try something smaller (e.g. bs=1M) but you should use more than the default (especially on recent disk hardware with sectors of 4Kbytes, i.e. Advanced Format). I naively recommend some power of two which is at least a megabyte.

With the default 512 bytes buffer size, I guess (but I could be very wrong) that the hardware requires the kernel to transfer 4K for each 512 bytes block.

Regarding rdsk, the sd(4) man pages say:

At this time, only block devices are provided. Raw devices have not yet been implemented.

Increase of dd's buffer size will give you more performance for read and write operations. Now all disks have hardware read/write buffer. But if you will increase dd's buffer size more than hardware buffer its performance will decrease because dd will read from first disk to buffer when second disk will have written all from its own hardware buffer. You need set bs option of dd command each time different value for different devices.

dd has many (weird) options, see dd(1).

You should explicitly state the buffer size, so try

dd if=/dev/sda of=/dev/sdb bs=16M

IIRC, the default buffer size is only 512 bytes. The command above sets it to 16 megabytes. You could try something smaller (e.g. bs=1M) but you should use more than the default (especially on recent disk hardware with sectors of 4Kbytes, i.e. Advanced Format). I naively recommend some power of two which is at least a megabyte.

With the default 512 bytes buffer size, I guess (but I could be very wrong) that the hardware requires the kernel to transfer 4K for each 512 bytes block.

Regarding rdsk, the sd(4) man pages say:

At this time, only block devices are provided. Raw devices have not yet been implemented.

dd has many (weird) options, see dd(1).

You should explicitly state the buffer size, so try

dd if=/dev/sda of=/dev/sdb bs=16M

IIRC, the default buffer size is only 512 bytes. The command above sets it to 16 megabytes. You could try something smaller (e.g. bs=1M) but you should use more than the default (especially on recent disk hardware with sectors of 4Kbytes, i.e. Advanced Format). I naively recommend some power of two which is at least a megabyte.

With the default 512 bytes buffer size, I guess (but I could be very wrong) that the hardware requires the kernel to transfer 4K for each 512 bytes block.

Regarding rdsk, the sd(4) man pages say:

At this time, only block devices are provided. Raw devices have not yet been implemented.

Increase of dd's buffer size will give you more performance for read and write operations. Now all disks have hardware read/write buffer. But if you will increase dd's buffer size more than hardware buffer its performance will decrease because dd will read from first disk to buffer when second disk will have written all from its own hardware buffer. You need set bs option of dd command each time different value for different devices.

5 added missing word
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dd has many (weird) options, see dd(1).

You probably should explicitexplicitly state the buffer size, so try

dd if=/dev/sda of=/dev/sdb bs=16M

IIRC, the default buffer size is only 512 bytes. The command above sets it to 16 megabytes. You could try something smaller (e.g. bs=1M) but you should use more than the default (especially on recent disk hardware with sectors of 4Kbytes, i.e. Advanced Format). I naively recommend some power of two which is at least a megabyte.

With the default 512 bytes buffer size, I guess (but I could be very wrong) that the hardware requires the kernel to transfer 4K for each 512 bytes block.

Regarding rdsk, the sd(4) man pages say:

At this time, only block devices are provided. Raw devices have not yet been implemented.

dd has many (weird) options, see dd(1).

You probably should explicit the buffer size, so try

dd if=/dev/sda of=/dev/sdb bs=16M

IIRC, the default buffer size is only 512 bytes. The command above sets it to 16 megabytes. You could try something smaller (e.g. bs=1M) but you should use more than the default (especially on recent disk hardware with sectors of 4Kbytes, i.e. Advanced Format). I naively recommend some power of two which is at least a megabyte.

With the default 512 bytes buffer size, I guess (but I could be very wrong) that the hardware requires the kernel to transfer 4K for each 512 bytes block.

Regarding rdsk, the sd(4) man pages say:

At this time, only block devices are provided. Raw devices have not yet been implemented.

dd has many (weird) options, see dd(1).

You should explicitly state the buffer size, so try

dd if=/dev/sda of=/dev/sdb bs=16M

IIRC, the default buffer size is only 512 bytes. The command above sets it to 16 megabytes. You could try something smaller (e.g. bs=1M) but you should use more than the default (especially on recent disk hardware with sectors of 4Kbytes, i.e. Advanced Format). I naively recommend some power of two which is at least a megabyte.

With the default 512 bytes buffer size, I guess (but I could be very wrong) that the hardware requires the kernel to transfer 4K for each 512 bytes block.

Regarding rdsk, the sd(4) man pages say:

At this time, only block devices are provided. Raw devices have not yet been implemented.

4 added 68 characters in body
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dd has many (weird) options, see dd(1).

You probably should explicit the buffer size, so try

dd if=/dev/sda of=/dev/sdb bs=16M

IIRC, the default buffer size is only 512 bytes. The command above sets it to 16 megabytes. You could try something smaller (e.g. bs=1M) but you should use more than the default (especially on recent disk hardware with sectors of 4Kbytes, i.e. Advanced Format). I naively recommend some power of two which is at least a megabyte.

With the default 512 bytes buffer size, I guess (but I could be very wrong) that the hardware requires the kernel to transfer 4K for each 512 bytes block.

Regarding rdsk, the sd(4) man pages say:

At this time, only block devices are provided. Raw devices have not yet been implemented.

dd has many (weird) options, see dd(1).

You probably should explicit the buffer size, so try

dd if=/dev/sda of=/dev/sdb bs=16M

IIRC, the default buffer size is only 512 bytes. The command above sets it to 16 megabytes. You could try something smaller (e.g. bs=1M) but you should use more than the default (especially on recent disk hardware with sectors of 4Kbytes, i.e. Advanced Format).

With the default 512 bytes buffer size, I guess (but I could be very wrong) that the hardware requires the kernel to transfer 4K for each 512 bytes block.

Regarding rdsk, the sd(4) man pages say:

At this time, only block devices are provided. Raw devices have not yet been implemented.

dd has many (weird) options, see dd(1).

You probably should explicit the buffer size, so try

dd if=/dev/sda of=/dev/sdb bs=16M

IIRC, the default buffer size is only 512 bytes. The command above sets it to 16 megabytes. You could try something smaller (e.g. bs=1M) but you should use more than the default (especially on recent disk hardware with sectors of 4Kbytes, i.e. Advanced Format). I naively recommend some power of two which is at least a megabyte.

With the default 512 bytes buffer size, I guess (but I could be very wrong) that the hardware requires the kernel to transfer 4K for each 512 bytes block.

Regarding rdsk, the sd(4) man pages say:

At this time, only block devices are provided. Raw devices have not yet been implemented.

3 added 209 characters in body
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2 added 243 characters in body
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