dd question.

[Guest_imported]

First my history, I have two disks of equal size in my E450. I am running on one disk and the other I want to use as a spare. I am currently doing a ufsdump/ufsrestore (via crontab) but was told that dd is better because I don't have to install a bootblk like I do with ufsrestore and everything should be good to go on startup. So here is my question, if I were to do a dd if=/dev/dsk/c0t0d0s2 of=/dev/dsk/c0t1d0s2 would that copy everything over? If not what do I need to do?

 

[tuka]

I would use this command dd if=/dev/rdsk/c0t0d0s2 of=/dev/rdsk/c0t1d0s2 bs=1024k

bs =block size in kilo dependent upon your virtual memory on the system. biiger blocks faster the dd. must be a multiple of 512.

Use rdsk instead of dsk.

 

[thelabguy]

that should do it!

keep in mind that this will take a while to finish, and you won't get a prompt again until it's done (unless following the command with the "&&quot. Jarod, The Lab Guy

 

[thelabguy]

doesn't the rdsk and dsk depend on your system?

Jarod, The Lab Guy

 

[jimbopalmer]

I cron this to copy my OS each night

cat /usr/local/bin/oscopy

#!/bin/sh
#
/usr/bin/dd if=/dev/dsk/c2t1d0s0 of=/dev/dsk/c2t2d0s0
/usr/bin/dd if=/dev/dsk/c2t1d0s6 of=/dev/dsk/c2t2d0s6
/usr/bin/dd if=/dev/dsk/c2t1d0s1 of=/dev/dsk/c2t2d0s1
/usr/bin/dd if=/dev/dsk/c2t1d0s5 of=/dev/dsk/c2t2d0s5
fsck -y /dev/dsk/c2t2d0s0
fsck -y /dev/dsk/c2t2d0s6
fsck -y /dev/dsk/c2t2d0s1
fsck -y /dev/dsk/c2t2d0s5 I tried to remain child-like, all I acheived was childish.

 

[thelabguy]

rdsk = raw disk will copy bit for bit where dsk will read it in blocks.

(had to look that one up) Jarod, The Lab Guy

 

[Guest_imported]

I was wondering if I needed to do the dd for each slice or if I could just be lazy and do it for slice 2 since its the whole disk. It seems that Jimbo is doing it individually which would lead me to believe that it the correct method. Thanks for all the feedback.

 

[thelabguy]

yes, you can do s2 instead of each individually. Jarod, The Lab Guy

 

[jimbopalmer]

I do slices as my swap is on both disks, and I do not wish to overwrite one swap with the other I tried to remain child-like, all I acheived was childish.

 

[Guest_imported]

I kicked off the dd yesterday and 13 hours later it is still running. Here's the syntax:

dd if=/dev/rdsk/c0t0d0s2 of=/dev/rdsk/c0t1d0s2

They are 18gb disks but 13 hours is way too long. Is this normal? I didn't add the bs=1024k. Would that account for the length of time? I'm going to try the slice by slice method next but it seems to me that ufsdump/restore is a lot faster.

 

[thelabguy]

Our 18gb dd takes about an hour. Jarod, The Lab Guy

 

[Guest_imported]

bs - block size is am important factor in dd .Default being 512 is very slow for large capacity disks.
setting bs=8192 that is 8k will greatly improve the dd speed.

Hemant

http://www.adminschoice.com