3 files changed, 7 insertions, 10 deletions
diff --git a/mkfs.c b/mkfs.c
index 5f1411f1..c58ab2f4 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -252,7 +252,6 @@ static int create_raid_groups(struct btrfs_trans_handle *trans,
 			      u64 metadata_profile, int mixed,
 			      struct mkfs_allocation *allocation)
 {
-	u64 num_devices = btrfs_super_num_devices(root->fs_info->super_copy);
 	int ret;
 
 	if (metadata_profile) {
@@ -271,7 +270,7 @@ static int create_raid_groups(struct btrfs_trans_handle *trans,
 		BUG_ON(ret);
 
 	}
-	if (!mixed && num_devices > 1 && data_profile) {
+	if (!mixed && data_profile) {
 		ret = create_one_raid_group(trans, root,
 					    BTRFS_BLOCK_GROUP_DATA |
 					    data_profile, allocation);
@@ -1603,7 +1602,7 @@ int main(int ac, char **av)
 		}
 	}
 	ret = test_num_disk_vs_raid(metadata_profile, data_profile,
-			dev_cnt, mixed);
+			dev_cnt, mixed, ssd);
 	if (ret)
 		exit(1);
 
diff --git a/utils.c b/utils.c
index 13835051..c20966c1 100644
--- a/utils.c
+++ b/utils.c
@@ -2463,7 +2463,7 @@ static int group_profile_devs_min(u64 flag)
 }
 
 int test_num_disk_vs_raid(u64 metadata_profile, u64 data_profile,
-	u64 dev_cnt, int mixed)
+	u64 dev_cnt, int mixed, int ssd)
 {
 	u64 allowed = 0;
 
@@ -2504,11 +2504,9 @@ int test_num_disk_vs_raid(u64 metadata_profile, u64 data_profile,
 		return 1;
 	}
 
-	if (!mixed && (data_profile & BTRFS_BLOCK_GROUP_DUP)) {
-		fprintf(stderr,
-			"ERROR: DUP for data is allowed only in mixed mode\n");
-		return 1;
-	}
+	warning_on(!mixed && (data_profile & BTRFS_BLOCK_GROUP_DUP) && ssd,
+		   "DUP have no effect if your SSD have deduplication function");
+
 	return 0;
 }
 
diff --git a/utils.h b/utils.h
index b6253306..6f3824c5 100644
--- a/utils.h
+++ b/utils.h
@@ -167,7 +167,7 @@ int test_dev_for_mkfs(char *file, int force_overwrite);
 int get_label_mounted(const char *mount_path, char *labelp);
 int get_label_unmounted(const char *dev, char *label);
 int test_num_disk_vs_raid(u64 metadata_profile, u64 data_profile,
-	u64 dev_cnt, int mixed);
+	u64 dev_cnt, int mixed, int ssd);
 int group_profile_max_safe_loss(u64 flags);
 int is_vol_small(char *file);
 int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,