--- readsector0.c.orig	2006-11-20 23:52:30.000000000 -0600
+++ readsector0.c	2006-11-20 23:54:05.000000000 -0600
@@ -10,14 +10,14 @@
 #include <fcntl.h>
 #include <sys/ioctl.h>
 #include <errno.h>
 
 #include "checkers.h"
+#include "readsector0.h"
 
 #include "../libmultipath/sg_include.h"
-
-#define SENSE_BUFF_LEN 32
+#include "../libmultipath/debug.h"
 
 #define MSG_READSECTOR0_UP	"readsector0 checker reports path is up"
 #define MSG_READSECTOR0_DOWN	"readsector0 checker reports path is down"
 
 struct readsector0_checker_context {
@@ -49,14 +49,16 @@
 	int bs = 512;
 	int cdbsz = 10;
 	int * diop = NULL;
 
 	unsigned char rdCmd[cdbsz];
+	unsigned char *sbb = senseBuff;
 	struct sg_io_hdr io_hdr;
 	int res;
 	int rd_opcode[] = {0x8, 0x28, 0xa8, 0x88};
 	int sz_ind;
+	int retry_count=3;
 	
 	memset(rdCmd, 0, cdbsz);
 	sz_ind = 1;
 	rdCmd[0] = rd_opcode[sz_ind];
 	rdCmd[2] = (unsigned char)((start_block >> 24) & 0xff);
@@ -78,10 +80,12 @@
 	io_hdr.timeout = DEF_TIMEOUT;
 	io_hdr.pack_id = (int)start_block;
 	if (diop && *diop)
 	io_hdr.flags |= SG_FLAG_DIRECT_IO;
 
+retry:	
+	memset(senseBuff, 0, SENSE_BUFF_LEN);
 	while (((res = ioctl(sg_fd, SG_IO, &io_hdr)) < 0) && (EINTR == errno));
 
 	if (res < 0) {
 		if (ENOMEM == errno) {
 			return PATH_UP;
@@ -92,19 +96,29 @@
 	if ((0 == io_hdr.status) &&
 	    (0 == io_hdr.host_status) &&
 	    (0 == io_hdr.driver_status)) {
 		return PATH_UP;
 	} else {
+		/*
+	 	 * Retry if UNIT_ATTENTION check condition.
+	 	 */
+		if ((sbb[2]&0xf) == 6) {
+			condlog(4, "readsector0_checker: Read error. "
+				"Sense data are 0x%x/0x%x/0x%x.",
+				sbb[2]&0xf, sbb[12], sbb[13]);
+			if (--retry_count)
+				goto retry;
+		}
 		return PATH_DOWN;
 	}
 }
 
 extern int
 readsector0 (struct checker * c)
 {
-	unsigned char buf[512];
 	unsigned char sbuf[SENSE_BUFF_LEN];
+	unsigned char buf[512];
 	int ret;
 
 	ret = sg_read(c->fd, &buf[0], &sbuf[0]);
 int * toto = *c->mpcontext;
 (*toto)++;