Help! Disk errors.

[VALERIE%umass-cs.csnet at csnet-relay.arpa]

 SOS!
 We are having severe difficulties with our disk drive. We are
running 4.2 BSD on a VAX 750 with one RA81 disk. 
After running for months without problems, our
machine crashed with the following type of error message :

uda0: hard error, disk transfer error unit 1, grp 0xffff8500, hdr 0x73
ra1a: hard error sn112 status 350

 DEC field service replaced the UDA50 board in the VAX. We did a 
physical backup of the disk and were up and running again. A day later we 
had another crash with the same type of error (on a different partition). 
DEC returned and replaced most of the disk drive.
 We ran tests on the disk for hours and had no problems. 

 Ever since then we have been crashing and getting these error messages.
We have switched disks, cables, restored a backup copy of vmunix. Nothing 
seems to help.



PS
Another error message was :

ra0a: hard error sn13434 udasa 100004 state 5
udintr: um_ubinfo == 0

 How do you interpret these messages?
I have heard there are problems with the RA81 driver. Is this what we
are experiencing? Does anyone have any suggestions on what we should
be doing.

 Please send any replies directly to me.

	Thank you,

	Valerie Caro
	CSNET:  VALERIE at UMASS-CS
        BITNET: VALERIE at UMASS