was the error similar to this ?

Session fails with error:     (712a0033)Internal information only. Copy Command 0x1C6BAFB3BC1C4B0 ( DId: 4, Originator: 0) is using a Buffer Count of 4 and a Buffer Size of 1024 blocks.

  00000400 06004c00 d3040000 33002a61 33002a61 00000000 00000000 00000000 00000000 00000000 712a0033                  Cpm

  (712a000f)Internal information only. Throttle value has been changed.

(Command: 0x1C6BAFB3BC1C4B0 DId: 4 Throttle Value: 6)

  00 00 04 00 04 00 4c 00 d3 04 00 00 0f 00 2a 61 0f 00 2a 61 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0 0 00 00 00 71 2a 00 0f         Cpm

  Bus 1 Enclosure 0 Disk 7(957) Uncorrectable Sector                    [0x00]   11448    12

001000

Here's is what is shows when i downloaded the SPA_Sancopy_info.txt using Triage...Copy Descriptor Name:  22

Copy Descriptor ID:  77
Owner:  SPB
Source LUN WWN:  60:06:01:60:2D:C0:24:00:56:6E:C2:94:BE:8A:DF:11
Number of Blocks to Copy:  4294967296
Number Of Destinations:  1
Destination LUN WWN:  60:06:01:60:18:A0:31:00:3C:1B:E6:5F:F2:36:E2:11
Session Status:  The Session failed because either the source or all destinations have failed.  Check the device that failed. For a device on a remote storage array, verify the FC zoning and/or iSCSI connection set and ensure that it is in the correct storage group.
Initial Throttle:  6
Current Throttle:  8
Transfer Count:  867328
Percent Complete:  0
Completion Time:  12/11/12 23:10:29
Failure Status:  A bad block was encountered on the source device. (0x712ac015)

Thanks Dynamox for your quick response, in fact i don't know where to find this message u just replied by.. on the other hand the message i have is in the Unisphere Gui, under migration, when i choose the failed session and click status, under the copy tab, this appears to be the status details: The Session failed because either the source or all destinations have failed. Check the device that failed and the path to it. For a device on a remote storage array, verify the zoning and ensure that it is in the correct storage group

then under the source tab, it says: a bad block was encountered on the source device.

Yeah i guess that's the case, i did some reading and as u said it appears that a background verify needs to be done.thanks for ur support dynamox. most appreciated.

Adding to what dynamox already mentioned, if you intend to use replicated data for restore/recovery. Please, also ensure the data integrity by means of host-based application-level data integrity mechanisms.

Thanks,

Ankit