AIX

I'm talking about dd command, can you please explain about dd command

my AIX version is : AIX 6.1

there is nothing in /tgtapp and it's empty mount point files system has the same size of /sfsapp

/sfsapp and /tgtapp are mount points and each one mointed on it own disk

Quite frankly, i don't understand your obsession with "dd", given that you have been offered several good alternatives. You will not gain anything by using "dd", not speed, not ease of use and definitely not safety. To me that starts to sound like homework.

Here is your solution, use at your own risk, i haven't tested it.

First find out the devices which are mounted at the respective mountpoints with the "mount" command, then use these devices as infile and outfile of "dd".

Example: copy "/ap101" to "/ap102".

Code:

# mount
  node       mounted        mounted over    vfs       date        options      
-------- ---------------  ---------------  ------ ------------ --------------- 
<...SNIP...>
         /dev/lvap101     /ap101           jfs2   Nov 29 11:33 rw,log=/dev/logapdev1vg
         /dev/lvap102     /ap102           jfs2   Nov 29 11:33 rw,nodev,nosuid,log=/dev/logapdev1vg
<...SNIP...>

# dd if=/dev/lvap101 of=/dev/lvap102 bs=512

I hope this helps.

bakunin

I have used the below command..

Code:

dd if=/dev/sfsapplv of=/dev/tgtapplv bs=512

but it's taking long time more than 30 min's without coping any thing to /tgtapp

After I canceled that , I got the below result

Code:

2352183+0 records in.
2352183+0 records out.

Can any one explain.. ?

I have no idea about your disks performance, but a quick estimation tells me: if the target disk can write at 20MB/s continuously then it will take (250.000/20=) 12500 seconds to write 250GB - 12500/3600 ~ 3.5 hours. I doubt your disk (LUN, whatever) can write at the ~140 MB/s (continuous!) necessary to finish the job in 30 minutes.

Could you be bothered to read the man page of "dd", after insisting on this tool, before asking here? It tells you that it has - until you cancelled it - 2352183 pieces of the size given in the command in option "bs" read and written as many. As you issued

Code:

dd if=/dev/sfsapplv of=/dev/tgtapplv bs=512

it read 2352183x512=1204317696 bytes and wrote as many.

Again, i don't think it is advisable to use "dd" for that task (even more it is dangerous in the hand of someone not completely knowing what he is doing) and i won't answer questions easily answered by looking at the man page again.

I hope this helps.

bakunin

it's huge data , I have tried to use your suggested command but it got hanged after some time and it did not copy whole the data

do you have any recommended command will be strong command to copy whole the files from /sfsapp to the new mount point /tgtapp

Have you tried the three other suggestions that were posted? If not start there.

You haven't said so until now. If so, what exactly was the error? The method i described (tar) has worked for me countless times, also on such amounts of data and even more.

Using "backup" and "restore", "cpio" or "savevg" will equally work and probably at roughly the same speed as "tar".

One thing though: you can't cancel a job after some time and expect it to have finished the task - if you have to cancel it that means it was still running and if it was running it means it hasn't finished what it was doing.

I hope this helps.

bakunin