OSH Data Set ERROR

[DSL]

Hi,
I am having some dataset error in orchestrate script.

Basically i want to check whether, my ds file is valid or not..

following is my osh script

copy <a.ds
| hash -key key1
| tsort -key -key key1
| innerjoin -key key1 <b.ds
| export -schemafile xxx.schema -append -file xxxx.txt

here a.ds file was corrupted.

when i execute above step, OSH keep on generating following message

****************
##E TFDM 000125 16:35:51(142) <input repartition(0),1> Failure opening IO port
##E TFDM 000120 16:35:51(143) <input repartition(0),1> Unable to open partition 1
##E TFIO 000161 16:35:51(144) <input repartition(0),1> I/O subsystem: Open of /apps/opt/xxxx/data/a.ds.xxxx.xxxx.0001.0001.0000.1edd.c26d14ea.0005.87f1cd44 failed: No such file or directory

****************

my log file size increasing..

to stop these messages i have to kill my osh job...

here before executing above step, i want to check, whether ds (here a.ds) file is valid or not ?

Can any one tel lme how to do this check ?

Thanks in Advance