diff --git a/test-tool/iscsi-test-cu.c b/test-tool/iscsi-test-cu.c
index 0591459..31ab549 100644
--- a/test-tool/iscsi-test-cu.c
+++ b/test-tool/iscsi-test-cu.c
@@ -296,6 +296,7 @@ static CU_TestInfo tests_extended_copy[] = {
         { "DescrType", test_extendedcopy_descr_type },
         { "ValidTgtDescr", test_extendedcopy_validate_tgt_descr },
         { "ValidSegDescr", test_extendedcopy_validate_seg_descr },
+        { "Large", test_extendedcopy_large },
         CU_TEST_INFO_NULL
 };
 
diff --git a/test-tool/iscsi-test-cu.h b/test-tool/iscsi-test-cu.h
index 4951080..601297d 100644
--- a/test-tool/iscsi-test-cu.h
+++ b/test-tool/iscsi-test-cu.h
@@ -63,6 +63,7 @@ void test_extendedcopy_descr_limits(void);
 void test_extendedcopy_descr_type(void);
 void test_extendedcopy_validate_tgt_descr(void);
 void test_extendedcopy_validate_seg_descr(void);
+void test_extendedcopy_large(void);
 
 void test_get_lba_status_simple(void);
 void test_get_lba_status_beyond_eol(void);
diff --git a/test-tool/test_extendedcopy_simple.c b/test-tool/test_extendedcopy_simple.c
index 797c77d..0f75945 100644
--- a/test-tool/test_extendedcopy_simple.c
+++ b/test-tool/test_extendedcopy_simple.c
@@ -97,3 +97,102 @@ test_extendedcopy_simple(void)
         free(buf1);
         free(buf2);
 }
+
+/* to save time, avoid copying more than 256M */
+#define TEST_XCOPY_LARGE_CP_LEN_MAX (256 * 1024 * 1024)
+void
+test_extendedcopy_large(void)
+{
+        struct scsi_task *edl_task = NULL;
+        struct scsi_copy_results_op_params *opp = NULL;
+        uint32_t cp_len_bytes = 0;
+        int i, tgt_desc_len = 0, seg_desc_len = 0, offset = XCOPY_DESC_OFFSET;
+        struct iscsi_data data;
+        unsigned char *xcopybuf;
+        unsigned int write_blocks;
+        unsigned char *buf1;
+        unsigned char *buf2;
+        uint64_t cp_dst_lba;
+
+        logging(LOG_VERBOSE, LOG_BLANK_LINE);
+        logging(LOG_VERBOSE,
+                "Test large EXTENDED COPY with type 0x0A segment descriptor");
+
+        CHECK_FOR_DATALOSS;
+
+        /* check for 0x0A type SD support, which offers 32-bit lengths */
+        RECEIVE_COPY_RESULTS(&edl_task, sd, SCSI_COPY_RESULTS_OP_PARAMS, 0,
+                             (void **)&opp, EXPECT_STATUS_GOOD);
+        CU_ASSERT_NOT_EQUAL(opp, NULL);
+
+        for (i = 0; i < opp->impl_desc_list_length; i++) {
+                if (opp->imp_desc_type_codes[i] == BLK_TO_BLK_OFF_SEG_DESCR) {
+                        cp_len_bytes = opp->max_segment_length;
+                        break;
+                }
+        }
+        scsi_free_scsi_task(edl_task);
+
+        if (cp_len_bytes == 0) {
+                CU_PASS("[SKIPPED] BLK_TO_BLK_OFF_SEG_DESCR not supported");
+        }
+        if (cp_len_bytes > TEST_XCOPY_LARGE_CP_LEN_MAX) {
+                cp_len_bytes = TEST_XCOPY_LARGE_CP_LEN_MAX;
+        }
+        if (num_blocks < (cp_len_bytes / block_size) * 2) {
+                CU_PASS("[SKIPPED] device too small to handle maxlen XCOPY");
+        }
+
+        write_blocks = num_blocks / 2;
+        if (write_blocks > 2048)
+                write_blocks = 2048;
+        buf1 = malloc(write_blocks * block_size);
+        buf2 = malloc(write_blocks * block_size);
+
+        cp_dst_lba = num_blocks - (cp_len_bytes / block_size);
+        logging(LOG_VERBOSE, "Zero %u blocks at the end of the LUN (LBA:%llu)",
+                write_blocks, (unsigned long long)cp_dst_lba);
+        memset(buf1, '\0', write_blocks * block_size);
+        WRITE16(sd, cp_dst_lba, write_blocks * block_size,
+                block_size, 0, 0, 0, 0, 0, buf1, EXPECT_STATUS_GOOD);
+        logging(LOG_VERBOSE, "Write %u blocks of 'B' at LBA:0", write_blocks);
+        memset(buf1, 'B', write_blocks * block_size);
+        WRITE16(sd, 0, write_blocks * block_size, block_size, 0, 0, 0, 0, 0,
+                buf1, EXPECT_STATUS_GOOD);
+
+        data.size = XCOPY_DESC_OFFSET +
+                get_desc_len(IDENT_DESCR_TGT_DESCR) +
+                get_desc_len(BLK_TO_BLK_OFF_SEG_DESCR);
+        data.data = alloca(data.size);
+        xcopybuf = data.data;
+        memset(xcopybuf, 0, data.size);
+
+        /* Initialize target descriptor list with one target descriptor */
+        offset += populate_tgt_desc(xcopybuf+offset, IDENT_DESCR_TGT_DESCR,
+                        LU_ID_TYPE_LUN, 0, 0, 0, 0, sd);
+        tgt_desc_len = offset - XCOPY_DESC_OFFSET;
+
+        /* Initialize segment descriptor list with one segment descriptor */
+        offset += populate_seg_desc_b2b_off(xcopybuf+offset, 0, 0, 0,
+                                  cp_len_bytes, 0, cp_dst_lba, 0, 0);
+        seg_desc_len = offset - XCOPY_DESC_OFFSET - tgt_desc_len;
+
+        /* Initialize the parameter list header */
+        populate_param_header(xcopybuf, 1, 0, LIST_ID_USAGE_DISCARD, 0,
+                        tgt_desc_len, seg_desc_len, 0);
+
+        EXTENDEDCOPY(sd, &data, EXPECT_STATUS_GOOD);
+
+        logging(LOG_VERBOSE, "Read %u blocks from end of the LUN",
+                write_blocks);
+        READ16(sd, NULL, cp_dst_lba, write_blocks * block_size,
+               block_size, 0, 0, 0, 0, 0, buf2,
+               EXPECT_STATUS_GOOD);
+
+        if (memcmp(buf1, buf2, write_blocks * block_size)) {
+                CU_FAIL("Blocks were not copied correctly");
+        }
+
+        free(buf1);
+        free(buf2);
+}