diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index 05891f84a..92bfd3ecf 100644
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -2409,7 +2409,7 @@ static const char *objset_types[DMU_OST_NUMTYPES] = {
 static void
 dump_dir(objset_t *os)
 {
-	dmu_objset_stats_t dds;
+	dmu_objset_stats_t dds = { 0 };
 	uint64_t object, object_count;
 	uint64_t refdbytes, usedobjs, scratch;
 	char numbuf[32];
@@ -5447,9 +5447,9 @@ dump_zpool(spa_t *spa)
 #define	ZDB_FLAG_BSWAP		0x0004
 #define	ZDB_FLAG_GBH		0x0008
 #define	ZDB_FLAG_INDIRECT	0x0010
-#define	ZDB_FLAG_PHYS		0x0020
-#define	ZDB_FLAG_RAW		0x0040
-#define	ZDB_FLAG_PRINT_BLKPTR	0x0080
+#define	ZDB_FLAG_RAW		0x0020
+#define	ZDB_FLAG_PRINT_BLKPTR	0x0040
+#define	ZDB_FLAG_VERBOSE	0x0080
 
 static int flagbits[256];
 
@@ -5580,11 +5580,30 @@ name:
 	return (NULL);
 }
 
+static boolean_t
+zdb_parse_block_sizes(char *sizes, uint64_t *lsize, uint64_t *psize)
+{
+	char *s0, *s1;
+
+	if (sizes == NULL)
+		return (B_FALSE);
+
+	s0 = strtok(sizes, "/");
+	if (s0 == NULL)
+		return (B_FALSE);
+	s1 = strtok(NULL, "/");
+	*lsize = strtoull(s0, NULL, 16);
+	*psize = s1 ? strtoull(s1, NULL, 16) : *lsize;
+	return (*lsize >= *psize && *psize > 0);
+}
+
+#define	ZIO_COMPRESS_MASK(alg)	(1ULL << (ZIO_COMPRESS_##alg))
+
 /*
  * Read a block from a pool and print it out.  The syntax of the
  * block descriptor is:
  *
- *	pool:vdev_specifier:offset:size[:flags]
+ *	pool:vdev_specifier:offset:[lsize/]psize[:flags]
  *
  *	pool           - The name of the pool you wish to read from
  *	vdev_specifier - Which vdev (see comment for zdb_vdev_lookup)
@@ -5597,8 +5616,8 @@ name:
  *		 e: Byteswap data before dumping
  *		 g: Display data as a gang block header
  *		 i: Display as an indirect block
- *		 p: Do I/O to physical offset
  *		 r: Dump raw data to stdout
+ *		 v: Verbose
  *
  */
 static void
@@ -5607,13 +5626,12 @@ zdb_read_block(char *thing, spa_t *spa)
 	blkptr_t blk, *bp = &blk;
 	dva_t *dva = bp->blk_dva;
 	int flags = 0;
-	uint64_t offset = 0, size = 0, psize = 0, lsize = 0, blkptr_offset = 0;
+	uint64_t offset = 0, psize = 0, lsize = 0, blkptr_offset = 0;
 	zio_t *zio;
 	vdev_t *vd;
 	abd_t *pabd;
 	void *lbuf, *buf;
-	const char *s, *vdev;
-	char *p, *dup, *flagstr;
+	char *s, *p, *dup, *vdev, *flagstr, *sizes;
 	int i, error;
 	boolean_t borrowed = B_FALSE;
 
@@ -5622,18 +5640,14 @@ zdb_read_block(char *thing, spa_t *spa)
 	vdev = s ? s : "";
 	s = strtok(NULL, ":");
 	offset = strtoull(s ? s : "", NULL, 16);
+	sizes = strtok(NULL, ":");
 	s = strtok(NULL, ":");
-	size = strtoull(s ? s : "", NULL, 16);
-	s = strtok(NULL, ":");
-	if (s)
-		flagstr = strdup(s);
-	else
-		flagstr = strdup("");
+	flagstr = strdup(s ? s : "");
 
 	s = NULL;
-	if (size == 0)
-		s = "size must not be zero";
-	if (!IS_P2ALIGNED(size, DEV_BSIZE))
+	if (!zdb_parse_block_sizes(sizes, &lsize, &psize))
+		s = "invalid size(s)";
+	if (!IS_P2ALIGNED(psize, DEV_BSIZE) || !IS_P2ALIGNED(lsize, DEV_BSIZE))
 		s = "size must be a multiple of sector size";
 	if (!IS_P2ALIGNED(offset, DEV_BSIZE))
 		s = "offset must be a multiple of sector size";
@@ -5689,9 +5703,6 @@ zdb_read_block(char *thing, spa_t *spa)
 			    vd->vdev_ops->vdev_op_type);
 	}
 
-	psize = size;
-	lsize = size;
-
 	pabd = abd_alloc_for_io(SPA_MAXBLOCKSIZE, B_FALSE);
 	lbuf = umem_alloc(SPA_MAXBLOCKSIZE, UMEM_NOFAIL);
 
@@ -5748,30 +5759,41 @@ zdb_read_block(char *thing, spa_t *spa)
 		 * We don't know how the data was compressed, so just try
 		 * every decompress function at every inflated blocksize.
 		 */
-		enum zio_compress c;
 		void *lbuf2 = umem_alloc(SPA_MAXBLOCKSIZE, UMEM_NOFAIL);
+		int cfuncs[ZIO_COMPRESS_FUNCTIONS] = { 0 };
+		int *cfuncp = cfuncs;
+		uint64_t maxlsize = SPA_MAXBLOCKSIZE;
+		uint64_t mask = ZIO_COMPRESS_MASK(ON) | ZIO_COMPRESS_MASK(OFF) |
+		    ZIO_COMPRESS_MASK(INHERIT) | ZIO_COMPRESS_MASK(EMPTY) |
+		    (getenv("ZDB_NO_ZLE") ? ZIO_COMPRESS_MASK(ZLE) : 0);
+		*cfuncp++ = ZIO_COMPRESS_LZ4;
+		*cfuncp++ = ZIO_COMPRESS_LZJB;
+		mask |= ZIO_COMPRESS_MASK(LZ4) | ZIO_COMPRESS_MASK(LZJB);
+		for (int c = 0; c < ZIO_COMPRESS_FUNCTIONS; c++)
+			if (((1ULL << c) & mask) == 0)
+				*cfuncp++ = c;
 
 		/*
-		 * XXX - On the one hand, with SPA_MAXBLOCKSIZE at 16MB,
-		 * this could take a while and we should let the user know
+		 * On the one hand, with SPA_MAXBLOCKSIZE at 16MB, this
+		 * could take a while and we should let the user know
 		 * we are not stuck.  On the other hand, printing progress
-		 * info gets old after a while.  What to do?
+		 * info gets old after a while.  User can specify 'v' flag
+		 * to see the progression.
 		 */
-		for (lsize = psize + SPA_MINBLOCKSIZE;
-		    lsize <= SPA_MAXBLOCKSIZE; lsize += SPA_MINBLOCKSIZE) {
-			for (c = 0; c < ZIO_COMPRESS_FUNCTIONS; c++) {
-				/*
-				 * ZLE can easily decompress non zle stream.
-				 * So have an option to disable it.
-				 */
-				if (c == ZIO_COMPRESS_ZLE &&
-				    getenv("ZDB_NO_ZLE"))
-					continue;
-
-				(void) fprintf(stderr,
-				    "Trying %05llx -> %05llx (%s)\n",
-				    (u_longlong_t)psize, (u_longlong_t)lsize,
-				    zio_compress_table[c].ci_name);
+		if (lsize == psize)
+			lsize += SPA_MINBLOCKSIZE;
+		else
+			maxlsize = lsize;
+		for (; lsize <= maxlsize; lsize += SPA_MINBLOCKSIZE) {
+			for (cfuncp = cfuncs; *cfuncp; cfuncp++) {
+				if (flags & ZDB_FLAG_VERBOSE) {
+					(void) fprintf(stderr,
+					    "Trying %05llx -> %05llx (%s)\n",
+					    (u_longlong_t)psize,
+					    (u_longlong_t)lsize,
+					    zio_compress_table[*cfuncp].\
+					    ci_name);
+				}
 
 				/*
 				 * We randomize lbuf2, and decompress to both
@@ -5780,27 +5802,30 @@ zdb_read_block(char *thing, spa_t *spa)
 				 */
 				VERIFY0(random_get_pseudo_bytes(lbuf2, lsize));
 
-				if (zio_decompress_data(c, pabd,
+				if (zio_decompress_data(*cfuncp, pabd,
 				    lbuf, psize, lsize) == 0 &&
-				    zio_decompress_data(c, pabd,
+				    zio_decompress_data(*cfuncp, pabd,
 				    lbuf2, psize, lsize) == 0 &&
 				    bcmp(lbuf, lbuf2, lsize) == 0)
 					break;
 			}
-			if (c != ZIO_COMPRESS_FUNCTIONS)
+			if (*cfuncp != 0)
 				break;
 		}
 		umem_free(lbuf2, SPA_MAXBLOCKSIZE);
 
-		if (lsize > SPA_MAXBLOCKSIZE) {
+		if (lsize > maxlsize) {
 			(void) printf("Decompress of %s failed\n", thing);
 			goto out;
 		}
 		buf = lbuf;
-		size = lsize;
+		if (*cfuncp == ZIO_COMPRESS_ZLE) {
+			printf("\nZLE decompression was selected. If you "
+			    "suspect the results are wrong,\ntry avoiding ZLE "
+			    "by setting and exporting ZDB_NO_ZLE=\"true\"\n");
+		}
 	} else {
-		size = psize;
-		buf = abd_borrow_buf_copy(pabd, size);
+		buf = abd_borrow_buf_copy(pabd, lsize);
 		borrowed = B_TRUE;
 	}
 
@@ -5808,14 +5833,14 @@ zdb_read_block(char *thing, spa_t *spa)
 		zdb_print_blkptr((blkptr_t *)(void *)
 		    ((uintptr_t)buf + (uintptr_t)blkptr_offset), flags);
 	else if (flags & ZDB_FLAG_RAW)
-		zdb_dump_block_raw(buf, size, flags);
+		zdb_dump_block_raw(buf, lsize, flags);
 	else if (flags & ZDB_FLAG_INDIRECT)
-		zdb_dump_indirect((blkptr_t *)buf, size / sizeof (blkptr_t),
+		zdb_dump_indirect((blkptr_t *)buf, lsize / sizeof (blkptr_t),
 		    flags);
 	else if (flags & ZDB_FLAG_GBH)
 		zdb_dump_gbh(buf, flags);
 	else
-		zdb_dump_block(thing, buf, size, flags);
+		zdb_dump_block(thing, buf, lsize, flags);
 
 	/*
 	 * If :c was specified, iterate through the checksum table to
@@ -5879,7 +5904,7 @@ zdb_read_block(char *thing, spa_t *spa)
 	}
 
 	if (borrowed)
-		abd_return_buf_copy(pabd, buf, size);
+		abd_return_buf_copy(pabd, buf, lsize);
 
 out:
 	abd_free(pabd);
@@ -6294,8 +6319,8 @@ main(int argc, char **argv)
 		flagbits['e'] = ZDB_FLAG_BSWAP;
 		flagbits['g'] = ZDB_FLAG_GBH;
 		flagbits['i'] = ZDB_FLAG_INDIRECT;
-		flagbits['p'] = ZDB_FLAG_PHYS;
 		flagbits['r'] = ZDB_FLAG_RAW;
+		flagbits['v'] = ZDB_FLAG_VERBOSE;
 
 		for (int i = 0; i < argc; i++)
 			zdb_read_block(argv[i], spa);
diff --git a/man/man8/zdb.8 b/man/man8/zdb.8
index 4f74c4b26..e907d03fe 100644
--- a/man/man8/zdb.8
+++ b/man/man8/zdb.8
@@ -63,7 +63,7 @@
 .Op Fl A
 .Op Fl e Oo Fl V Oc Op Fl p Ar path ...
 .Op Fl U Ar cache
-.Ar poolname vdev Ns \&: Ns Ar offset Ns \&: Ns Ar size Ns Op : Ns Ar flags
+.Ar poolname vdev Ns \&: Ns Ar offset Ns \&: Ns Ar [<lsize>/]<psize> Ns Op : Ns Ar flags
 .Nm
 .Fl S
 .Op Fl AP
@@ -227,7 +227,7 @@ This option can be combined with
 .Fl v
 for increasing verbosity.
 .It Xo
-.Fl R Ar poolname vdev Ns \&: Ns Ar offset Ns \&: Ns Ar size Ns Op : Ns Ar flags
+.Fl R Ar poolname vdev Ns \&: Ns Ar offset Ns \&: Ns Ar [<lsize>/]<psize> Ns Op : Ns Ar flags
 .Xc
 Read and display a block from the specified device.
 By default the block is displayed as a hex dump, but see the description of the
@@ -240,8 +240,8 @@ The block is specified in terms of a colon-separated tuple
 .Ar offset
 .Pq the offset within the vdev
 .Ar size
-.Pq the size of the block to read
-and, optionally,
+.Pq the physical size, or logical size / physical size
+of the block to read and, optionally,
 .Ar flags
 .Pq a set of flags, described below .
 .Pp
@@ -262,6 +262,8 @@ Dump gang block header
 Dump indirect block
 .It Sy r
 Dump raw uninterpreted block data
+.It Sy v
+Verbose output for guessing compression algorithm
 .El
 .It Fl s
 Report statistics on
diff --git a/module/zfs/zio_compress.c b/module/zfs/zio_compress.c
index cdaade27c..01c51347f 100644
--- a/module/zfs/zio_compress.c
+++ b/module/zfs/zio_compress.c
@@ -159,7 +159,6 @@ zio_decompress_data(enum zio_compress c, abd_t *src, void *dst,
 	 * the checksum.  However, for extra protection (e.g. against bitflips
 	 * in non-ECC RAM), we handle this error (and test it).
 	 */
-	ASSERT0(ret);
 	if (zio_decompress_fail_fraction != 0 &&
 	    spa_get_random(zio_decompress_fail_fraction) == 0)
 		ret = SET_ERROR(EINVAL);
diff --git a/tests/runfiles/linux.run b/tests/runfiles/linux.run
index 916631e41..6579cc748 100644
--- a/tests/runfiles/linux.run
+++ b/tests/runfiles/linux.run
@@ -106,7 +106,7 @@ tags = ['functional', 'clean_mirror']
 
 [tests/functional/cli_root/zdb]
 tests = ['zdb_001_neg', 'zdb_002_pos', 'zdb_003_pos', 'zdb_004_pos',
-    'zdb_005_pos', 'zdb_006_pos', 'zdb_checksum']
+    'zdb_005_pos', 'zdb_006_pos', 'zdb_checksum', 'zdb_decompress']
 pre =
 post =
 tags = ['functional', 'cli_root', 'zdb']
diff --git a/tests/zfs-tests/tests/functional/cli_root/zdb/Makefile.am b/tests/zfs-tests/tests/functional/cli_root/zdb/Makefile.am
index 0c4de2b25..9f143078f 100644
--- a/tests/zfs-tests/tests/functional/cli_root/zdb/Makefile.am
+++ b/tests/zfs-tests/tests/functional/cli_root/zdb/Makefile.am
@@ -6,4 +6,5 @@ dist_pkgdata_SCRIPTS = \
 	zdb_004_pos.ksh \
 	zdb_005_pos.ksh \
 	zdb_006_pos.ksh \
-	zdb_checksum.ksh
+	zdb_checksum.ksh \
+	zdb_decompress.ksh
diff --git a/tests/zfs-tests/tests/functional/cli_root/zdb/zdb_decompress.ksh b/tests/zfs-tests/tests/functional/cli_root/zdb/zdb_decompress.ksh
new file mode 100755
index 000000000..0e468d7c9
--- /dev/null
+++ b/tests/zfs-tests/tests/functional/cli_root/zdb/zdb_decompress.ksh
@@ -0,0 +1,119 @@
+#!/bin/ksh
+
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright (c) 2019 by Datto, Inc. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+
+#
+# Description:
+# zdb -R pool <DVA>:d will display the correct data and length
+#
+# Strategy:
+# 1. Create a pool, set compression to lzjb
+# 2. Write some identifiable data to a file
+# 3. Run zdb -ddddddbbbbbb against the file
+# 4. Record the DVA, lsize, and psize of L0 block 0
+# 5. Run zdb -R with :d flag and match the data
+# 6. Run zdb -R with :dr flags and match the lsize/psize
+# 7. Run zdb -R with :dr flags and match the lsize
+# 8. Run zdb -R with :dr flags and match the psize
+#
+
+
+function cleanup
+{
+	datasetexists $TESTPOOL && destroy_pool $TESTPOOL
+}
+
+log_assert "Verify zdb -R :d flag (decompress) works as expected"
+log_onexit cleanup
+init_data=$TESTDIR/file1
+write_count=256
+blksize=4096
+pattern="_match__pattern_"
+verify_runnable "global"
+verify_disk_count "$DISKS" 2
+
+default_mirror_setup_noexit $DISKS
+log_must zfs set recordsize=$blksize $TESTPOOL/$TESTFS
+log_must zfs set compression=lzjb $TESTPOOL/$TESTFS
+
+# 16 chars 256 times = 4k = block size
+typeset four_k=""
+for i in {1..$write_count}
+do
+	four_k=$four_k$pattern
+done
+
+# write the 4k block 256 times
+for i in {1..$write_count}
+do
+	echo $four_k >> $init_data
+done
+
+sync_pool $TESTPOOL true
+
+# get object number of file
+listing=$(ls -i $init_data)
+set -A array $listing
+obj=${array[0]}
+log_note "file $init_data has object number $obj"
+
+output=$(zdb -ddddddbbbbbb $TESTPOOL/$TESTFS $obj 2> /dev/null \
+    |grep -m 1 "L0 DVA" |head -n1)
+dva=$(grep -oP 'DVA\[0\]=<\K.*?(?=>)' <<< "$output")
+log_note "block 0 of $init_data has a DVA of $dva"
+
+# use the length reported by zdb -ddddddbbbbbb
+size_str=$(grep -oP 'size=\K.*?(?= )' <<< "$output")
+log_note "block size $size_str"
+
+vdev=$(echo "$dva" |awk '{split($0,array,":")} END{print array[1]}')
+offset=$(echo "$dva" |awk '{split($0,array,":")} END{print array[2]}')
+output=$(zdb -R $TESTPOOL $vdev:$offset:$size_str:d 2> /dev/null)
+echo $output |grep $pattern > /dev/null
+(( $? != 0 )) && log_fail "zdb -R :d failed to decompress the data properly"
+
+output=$(zdb -R $TESTPOOL $vdev:$offset:$size_str:dr 2> /dev/null)
+echo $output |grep $four_k > /dev/null
+(( $? != 0 )) && log_fail "zdb -R :dr failed to decompress the data properly"
+
+output=$(zdb -R $TESTPOOL $vdev:$offset:$size_str:dr 2> /dev/null)
+result=${#output}
+(( $result != $blksize)) && log_fail \
+"zdb -R failed to decompress the data to the length (${#output} != $size_str)"
+
+# decompress using lsize
+lsize=$(echo $size_str |awk '{split($0,array,"/")} END{print array[1]}')
+psize=$(echo $size_str |awk '{split($0,array,"/")} END{print array[2]}')
+output=$(zdb -R $TESTPOOL $vdev:$offset:$lsize:dr 2> /dev/null)
+result=${#output}
+(( $result != $blksize)) && log_fail \
+"zdb -R failed to decompress the data (length ${#output} != $blksize)"
+
+# Specifying psize will decompress successfully , but not always to full
+# lsize since zdb has to guess lsize incrementally.
+output=$(zdb -R $TESTPOOL $vdev:$offset:$psize:dr 2> /dev/null)
+result=${#output}
+# convert psize to decimal
+psize_orig=$psize
+psize=${psize%?}
+psize=$((16#$psize))
+(( $result < $psize)) && log_fail \
+"zdb -R failed to decompress the data with psize $psize_orig\
+ (length ${#output} < $psize)"
+
+log_pass "zdb -R :d flag (decompress) works as expected"