dd fails with I/O error message

[hp_user_1]

Hi,

I have created a new filesystem (fsnew) that is slightly smaller than (fsold) filesystem which is 80% full. I need to copy everything from fsold to fsnew. I am using:

dd if=/dev/vg01/rlvol1 of=/dev/vg02/rlvol1 bs=4096k

After a while the dd command fails and says I/O error.

Please help.

[Charles McCary]

Hmmm...usually this is indicative of a bad disk. Any particular reason you're trying to move this filesystem (bad h/w maybe?)

[hp_user_1]

Source is sitting on disk array 1 and the target is on disk array 2. We have to get rid of disk array 1 asap.

[Charles McCary]

Also, check this link, they had an lvextend issue:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=687357

[hp_user_1]

I don't have the lvextend issue.

[Alex Lavrov.]

run: dmesg

check /var/adm/syslog/syslog.log


any errors?


Alex.

[hp_user_1]

I don't see any error messages that point to disks.

I actually need to copy from 15 filesystems. I have successfully completed 3 of them.

[Ivan Ferreira · Accepted solution]

I don't like dd for copying entire filesystems. This is for several reasons:

You are copying also metadata and LVM information may differ because the sizes are differents.

You copy also empty blocks.

Use cp -Rp or cpio, tar or fbackup/frecover with a pipe to copy the filesystems .

[Alex Lavrov.]

If there are no hardware messages, it means that your FS is corrupted or you don't use dd correctly.

Just copy it as it's stated in the post above me.

Alex.

[AwadheshPandey]

just check ur disk with
dd if=/dev/dsk/cxtxdx of=/dev/null bs=1024k
and post the result

Awadhesh

[Peter Nikitka]

Hi,

you can use filesystem dump/restore utilities to duplicate filesystem. This will work form larger to smaller filesystems, if the size in the new filesystem is big enough to hold the data.
A dd will always try to copy ALL blocks of the device and you will never succeed in copying a larger to a smaller device.

VXFS: vxdump/vxrestore - see the man pages for details.

mfG Peter

[Andy Torres]

I've used vxdump/vxrestore to copy/move large amounts of data successfully, even over a network from one host to another.

/usr/sbin/vxdump 0f - /dev/vgXX/lvYY | remsh '(cd ;/usr/sbin/vxrestore -rf -)'

I'm sure the syntax for local copying is very similar, maybe something like:

/usr/sbin/vxdump 0f - /dev/vgXX/lvYY | '(cd ;/usr/sbin/vxrestore -rf -)'

or

/usr/sbin/vxdump 0f - /dev/vgXX/lvYY | cd ;/usr/sbin/vxrestore -rf -

[Kent Ostby]

Also, do an lvdisplay -v /dev/vg01/lvol1 | grep -i stale.

This may isolate the disk for you.

Or for each pv in the VG, do:

pvdisplay -v /dev/dsk/cXtYdZ | more and look for the ???????

Or

dd if=/dev/rdsk/CxtYdZ of=/dev/null bs=64k

and see which one gives you an I/O error.

[hp_user_1]

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