diff mbox

[5/6] fstests: btrfs: test RAID1 device reappear and balanced

Message ID 1463495530-425-5-git-send-email-anand.jain@oracle.com (mailing list archive)
State Not Applicable
Headers show

Commit Message

Anand Jain May 17, 2016, 2:32 p.m. UTC
The test does the following:
  Initialize a RAID1 with some data

  Re-mount RAID1 degraded with _dev1_ and write up to
  half of the FS capacity
  Save md5sum checkpoint1

  Re-mount healthy RAID1

  Let balance re-silver.
  Save md5sum checkpoint2

  Re-mount RAID1 degraded with _dev2_
  Save md5sum checkpoint3

  Verify if all three md5sum match

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 tests/btrfs/121     | 163 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/btrfs/121.out |   8 +++
 tests/btrfs/group   |   1 +
 3 files changed, 172 insertions(+)
 create mode 100755 tests/btrfs/121
 create mode 100644 tests/btrfs/121.out

Comments

Eryu Guan June 12, 2016, 5:06 a.m. UTC | #1
On Tue, May 17, 2016 at 10:32:09PM +0800, Anand Jain wrote:
> The test does the following:
>   Initialize a RAID1 with some data
> 
>   Re-mount RAID1 degraded with _dev1_ and write up to
>   half of the FS capacity
>   Save md5sum checkpoint1
> 
>   Re-mount healthy RAID1
> 
>   Let balance re-silver.
>   Save md5sum checkpoint2
> 
>   Re-mount RAID1 degraded with _dev2_
>   Save md5sum checkpoint3
> 
>   Verify if all three md5sum match
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>  tests/btrfs/121     | 163 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  tests/btrfs/121.out |   8 +++
>  tests/btrfs/group   |   1 +
>  3 files changed, 172 insertions(+)
>  create mode 100755 tests/btrfs/121
>  create mode 100644 tests/btrfs/121.out
> 
> diff --git a/tests/btrfs/121 b/tests/btrfs/121
> new file mode 100755
> index 000000000000..81b7deb047af
> --- /dev/null
> +++ b/tests/btrfs/121
> @@ -0,0 +1,163 @@
> +#! /bin/bash
> +# FS QA Test 121
> +#
> +# This test verify the RAID1 reconstruction on the reappeared
> +# device. By using the following steps:
> +# Initialize a RAID1 with some data
> +#
> +# Re-mount RAID1 degraded with dev2 missing and write up to
> +# half of the FS capacity.
> +# Save md5sum checkpoint1
> +#
> +# Re-mount healthy RAID1
> +#
> +# Let balance re-silver.
> +# Save md5sum checkpoint2
> +#
> +# Re-mount RAID1 degraded with dev1 missing
> +# Save md5sum checkpoint3
> +#
> +# Verify if all three checkpoints match
> +#
> +#---------------------------------------------------------------------
> +# Copyright (c) 2016 Oracle.  All Rights Reserved.
> +#
> +# This program is free software; you can redistribute it and/or
> +# modify it under the terms of the GNU General Public License as
> +# published by the Free Software Foundation.
> +#
> +# This program is distributed in the hope that it would be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program; if not, write the Free Software Foundation,
> +# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
> +#---------------------------------------------------------------------
> +#
> +
> +seq=`basename $0`
> +seqres=$RESULT_DIR/$seq
> +echo "QA output created by $seq"
> +
> +here=`pwd`
> +status=1	# failure is the default!
> +trap "_cleanup; exit \$status" 0 1 2 3 15
> +
> +_cleanup()
> +{
> +	cd /

The "rm -f $tmp.*" is still needed even $tmp.* is not used in the test
itself, it's still possible to be used by some helper functions.

> +}
> +
> +# get standard environment, filters and checks
> +. ./common/rc
> +. ./common/filter
> +
> +# remove previous $seqres.full before test
> +rm -f $seqres.full
> +
> +# real QA test starts here
> +
> +_supported_fs btrfs
> +_supported_os Linux
> +_require_scratch_nocheck
> +_require_scratch_dev_pool 2
> +
> +# the mounted test dir prevent btrfs unload, we need to unmount
> +_test_unmount
> +_require_btrfs_unloadable
> +
> +_scratch_dev_pool_get 2
> +
> +dev1=`echo $SCRATCH_DEV_POOL | awk '{print $1}'`
> +dev2=`echo $SCRATCH_DEV_POOL | awk '{print $2}'`
> +
> +dev1_sz=`blockdev --getsize64 $dev1`
> +dev2_sz=`blockdev --getsize64 $dev2`
> +# get min of both
> +max_fs_sz=`echo -e "$dev1_sz\n$dev2_sz" | sort | head -1`
> +max_fs_sz=$(( max_fs_sz/2 ))
> +if [ $max_fs_sz -gt 1000000 ]; then
> +	bs="1M"
> +	count=$(( max_fs_sz/1000000 ))
> +else
> +	max_fs_sz=$(( max_fs_sz*2 ))
> +	_notrun "Smallest dev size $max_fs_sz, Need at least 2M"
> +fi
> +
> +echo >> $seqres.full
> +echo "max_fs_sz=$max_fs_sz count=$count" >> $seqres.full
> +echo "-----Initialize -----" >> $seqres.full
> +_scratch_pool_mkfs "-mraid1 -draid1" >> $seqres.full 2>&1
> +_scratch_mount >> $seqres.full 2>&1
> +_run_btrfs_util_prog filesystem show
> +dd if=/dev/zero of="$SCRATCH_MNT"/tf1 bs=$bs count=1 \
> +					>>$seqres.full 2>&1
> +count=$(( count-- ))
> +echo "unmount" >> $seqres.full
> +echo "clean btrfs ko" >> $seqres.full
> +_scratch_unmount
> +_reload_btrfs_ko

A comment to explain the reason to reload btrfs.ko would be good.

> +
> +
> +echo >> $seqres.full
> +echo "-----Write degraded mount fill upto $max_fs_sz bytes-----" >> $seqres.full
> +echo
> +echo "Write data with degraded mount"
> +# Since we didn't run dev scan, btrfs kernel does not know
> +# about the dev2
> +# don't use _scratch_mount as we want to control
> +# the device used for mounting.
> +
> +_mount -o degraded $dev1 $SCRATCH_MNT >>$seqres.full 2>&1
> +_run_btrfs_util_prog filesystem show
> +dd if=/dev/zero of="$SCRATCH_MNT"/tf2 bs=$bs count=$count \
> +					>>$seqres.full 2>&1
> +checkpoint1=`md5sum $SCRATCH_MNT/tf2`
> +echo $checkpoint1 >> $seqres.full 2>&1
> +_scratch_unmount
> +echo "unmount" >> $seqres.full
> +
> +echo >> $seqres.full
> +echo "-----Mount normal-----" >> $seqres.full
> +echo
> +echo "Mount normal after balance"
> +_run_btrfs_util_prog device scan
> +_scratch_mount >> $seqres.full 2>&1
> +_run_btrfs_util_prog filesystem show
> +echo >> $seqres.full
> +_run_btrfs_util_prog balance start ${SCRATCH_MNT}
> +
> +checkpoint2=`md5sum $SCRATCH_MNT/tf2`
> +echo $checkpoint2 >> $seqres.full 2>&1
> +
> +echo >> $seqres.full
> +echo "-----Mount degraded but with other dev -----" >> $seqres.full
> +echo
> +echo "Mount degraded but with other dev"
> +_scratch_unmount
> +_reload_btrfs_ko
> +_mount -o degraded $dev2 $SCRATCH_MNT >>$seqres.full 2>&1
> +_run_btrfs_util_prog filesystem show
> +checkpoint3=`md5sum $SCRATCH_MNT/tf2`
> +echo $checkpoint3 >> $seqres.full 2>&1
> +
> +if [ "$checkpoint1" != "$checkpoint2" ]; then
> +	echo $checkpoint1
> +	echo $checkpoint2
> +	_fail "Inital sum does not match with after balance"
> +fi
> +
> +if [ "$checkpoint1" != "$checkpoint3" ]; then
> +	echo $checkpoint1
> +	echo $checkpoint3
> +	_fail "Inital sum does not match with data on dev2 written by balance"

Just "echo" error message, not _fail. _fail causes the test to exit,
leaves the following "_scratch_dev_pool_put; _test_mount" not run.

> +fi
> +
> +_scratch_dev_pool_put
> +_test_mount
> +
> +echo "Silence is golden"

There're outputs in golden image, then this line is not needed.

Thanks,
Eryu

> +status=0
> +exit
> diff --git a/tests/btrfs/121.out b/tests/btrfs/121.out
> new file mode 100644
> index 000000000000..0728787d17bc
> --- /dev/null
> +++ b/tests/btrfs/121.out
> @@ -0,0 +1,8 @@
> +QA output created by 121
> +
> +Write data with degraded mount
> +
> +Mount normal after balance
> +
> +Mount degraded but with other dev
> +Silence is golden
> diff --git a/tests/btrfs/group b/tests/btrfs/group
> index 90af8fc2d106..5c28a3ca0687 100644
> --- a/tests/btrfs/group
> +++ b/tests/btrfs/group
> @@ -122,3 +122,4 @@
>  118 auto quick snapshot metadata
>  119 auto quick snapshot metadata qgroup
>  120 auto quick snapshot metadata
> +121 auto replace
> -- 
> 2.7.0
> 
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Anand Jain June 15, 2016, 8:45 a.m. UTC | #2
On 06/12/2016 01:06 PM, Eryu Guan wrote:
> On Tue, May 17, 2016 at 10:32:09PM +0800, Anand Jain wrote:
>> The test does the following:
>>   Initialize a RAID1 with some data
>>
>>   Re-mount RAID1 degraded with _dev1_ and write up to
>>   half of the FS capacity
>>   Save md5sum checkpoint1
>>
>>   Re-mount healthy RAID1
>>
>>   Let balance re-silver.
>>   Save md5sum checkpoint2
>>
>>   Re-mount RAID1 degraded with _dev2_
>>   Save md5sum checkpoint3
>>
>>   Verify if all three md5sum match
>>
>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>> ---
>>  tests/btrfs/121     | 163 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>>  tests/btrfs/121.out |   8 +++
>>  tests/btrfs/group   |   1 +
>>  3 files changed, 172 insertions(+)
>>  create mode 100755 tests/btrfs/121
>>  create mode 100644 tests/btrfs/121.out
>>
>> diff --git a/tests/btrfs/121 b/tests/btrfs/121
>> new file mode 100755
>> index 000000000000..81b7deb047af
>> --- /dev/null
>> +++ b/tests/btrfs/121
>> @@ -0,0 +1,163 @@
>> +#! /bin/bash
>> +# FS QA Test 121
>> +#
>> +# This test verify the RAID1 reconstruction on the reappeared
>> +# device. By using the following steps:
>> +# Initialize a RAID1 with some data
>> +#
>> +# Re-mount RAID1 degraded with dev2 missing and write up to
>> +# half of the FS capacity.
>> +# Save md5sum checkpoint1
>> +#
>> +# Re-mount healthy RAID1
>> +#
>> +# Let balance re-silver.
>> +# Save md5sum checkpoint2
>> +#
>> +# Re-mount RAID1 degraded with dev1 missing
>> +# Save md5sum checkpoint3
>> +#
>> +# Verify if all three checkpoints match
>> +#
>> +#---------------------------------------------------------------------
>> +# Copyright (c) 2016 Oracle.  All Rights Reserved.
>> +#
>> +# This program is free software; you can redistribute it and/or
>> +# modify it under the terms of the GNU General Public License as
>> +# published by the Free Software Foundation.
>> +#
>> +# This program is distributed in the hope that it would be useful,
>> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> +# GNU General Public License for more details.
>> +#
>> +# You should have received a copy of the GNU General Public License
>> +# along with this program; if not, write the Free Software Foundation,
>> +# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
>> +#---------------------------------------------------------------------
>> +#
>> +
>> +seq=`basename $0`
>> +seqres=$RESULT_DIR/$seq
>> +echo "QA output created by $seq"
>> +
>> +here=`pwd`
>> +status=1	# failure is the default!
>> +trap "_cleanup; exit \$status" 0 1 2 3 15
>> +
>> +_cleanup()
>> +{
>> +	cd /
>
> The "rm -f $tmp.*" is still needed even $tmp.* is not used in the test
> itself, it's still possible to be used by some helper functions.

  I didn't set the tmp= either, so is it mandatory to set tmp=?
  Anyway have done it in v2.

>> +}
>> +
>> +# get standard environment, filters and checks
>> +. ./common/rc
>> +. ./common/filter
>> +
>> +# remove previous $seqres.full before test
>> +rm -f $seqres.full
>> +
>> +# real QA test starts here
>> +
>> +_supported_fs btrfs
>> +_supported_os Linux
>> +_require_scratch_nocheck
>> +_require_scratch_dev_pool 2
>> +
>> +# the mounted test dir prevent btrfs unload, we need to unmount
>> +_test_unmount
>> +_require_btrfs_unloadable
>> +
>> +_scratch_dev_pool_get 2
>> +
>> +dev1=`echo $SCRATCH_DEV_POOL | awk '{print $1}'`
>> +dev2=`echo $SCRATCH_DEV_POOL | awk '{print $2}'`
>> +
>> +dev1_sz=`blockdev --getsize64 $dev1`
>> +dev2_sz=`blockdev --getsize64 $dev2`
>> +# get min of both
>> +max_fs_sz=`echo -e "$dev1_sz\n$dev2_sz" | sort | head -1`
>> +max_fs_sz=$(( max_fs_sz/2 ))
>> +if [ $max_fs_sz -gt 1000000 ]; then
>> +	bs="1M"
>> +	count=$(( max_fs_sz/1000000 ))
>> +else
>> +	max_fs_sz=$(( max_fs_sz*2 ))
>> +	_notrun "Smallest dev size $max_fs_sz, Need at least 2M"
>> +fi
>> +
>> +echo >> $seqres.full
>> +echo "max_fs_sz=$max_fs_sz count=$count" >> $seqres.full
>> +echo "-----Initialize -----" >> $seqres.full
>> +_scratch_pool_mkfs "-mraid1 -draid1" >> $seqres.full 2>&1
>> +_scratch_mount >> $seqres.full 2>&1
>> +_run_btrfs_util_prog filesystem show
>> +dd if=/dev/zero of="$SCRATCH_MNT"/tf1 bs=$bs count=1 \
>> +					>>$seqres.full 2>&1
>> +count=$(( count-- ))
>> +echo "unmount" >> $seqres.full
>> +echo "clean btrfs ko" >> $seqres.full
>> +_scratch_unmount
>> +_reload_btrfs_ko
>
> A comment to explain the reason to reload btrfs.ko would be good.

yes. added.

>> +
>> +
>> +echo >> $seqres.full
>> +echo "-----Write degraded mount fill upto $max_fs_sz bytes-----" >> $seqres.full
>> +echo
>> +echo "Write data with degraded mount"
>> +# Since we didn't run dev scan, btrfs kernel does not know
>> +# about the dev2
>> +# don't use _scratch_mount as we want to control
>> +# the device used for mounting.
>> +
>> +_mount -o degraded $dev1 $SCRATCH_MNT >>$seqres.full 2>&1
>> +_run_btrfs_util_prog filesystem show
>> +dd if=/dev/zero of="$SCRATCH_MNT"/tf2 bs=$bs count=$count \
>> +					>>$seqres.full 2>&1
>> +checkpoint1=`md5sum $SCRATCH_MNT/tf2`
>> +echo $checkpoint1 >> $seqres.full 2>&1
>> +_scratch_unmount
>> +echo "unmount" >> $seqres.full
>> +
>> +echo >> $seqres.full
>> +echo "-----Mount normal-----" >> $seqres.full
>> +echo
>> +echo "Mount normal after balance"
>> +_run_btrfs_util_prog device scan
>> +_scratch_mount >> $seqres.full 2>&1
>> +_run_btrfs_util_prog filesystem show
>> +echo >> $seqres.full
>> +_run_btrfs_util_prog balance start ${SCRATCH_MNT}
>> +
>> +checkpoint2=`md5sum $SCRATCH_MNT/tf2`
>> +echo $checkpoint2 >> $seqres.full 2>&1
>> +
>> +echo >> $seqres.full
>> +echo "-----Mount degraded but with other dev -----" >> $seqres.full
>> +echo
>> +echo "Mount degraded but with other dev"
>> +_scratch_unmount
>> +_reload_btrfs_ko
>> +_mount -o degraded $dev2 $SCRATCH_MNT >>$seqres.full 2>&1
>> +_run_btrfs_util_prog filesystem show
>> +checkpoint3=`md5sum $SCRATCH_MNT/tf2`
>> +echo $checkpoint3 >> $seqres.full 2>&1
>> +
>> +if [ "$checkpoint1" != "$checkpoint2" ]; then
>> +	echo $checkpoint1
>> +	echo $checkpoint2
>> +	_fail "Inital sum does not match with after balance"
>> +fi
>> +
>> +if [ "$checkpoint1" != "$checkpoint3" ]; then
>> +	echo $checkpoint1
>> +	echo $checkpoint3
>> +	_fail "Inital sum does not match with data on dev2 written by balance"
>
> Just "echo" error message, not _fail. _fail causes the test to exit,
> leaves the following "_scratch_dev_pool_put; _test_mount" not run.

Ah. yes. Thanks fixed it.

>> +fi
>> +
>> +_scratch_dev_pool_put
>> +_test_mount
>> +
>> +echo "Silence is golden"
>
> There're outputs in golden image, then this line is not needed.

fixed it in v2.

Thanks, Anand


> Thanks,
> Eryu
>
>> +status=0
>> +exit
>> diff --git a/tests/btrfs/121.out b/tests/btrfs/121.out
>> new file mode 100644
>> index 000000000000..0728787d17bc
>> --- /dev/null
>> +++ b/tests/btrfs/121.out
>> @@ -0,0 +1,8 @@
>> +QA output created by 121
>> +
>> +Write data with degraded mount
>> +
>> +Mount normal after balance
>> +
>> +Mount degraded but with other dev
>> +Silence is golden
>> diff --git a/tests/btrfs/group b/tests/btrfs/group
>> index 90af8fc2d106..5c28a3ca0687 100644
>> --- a/tests/btrfs/group
>> +++ b/tests/btrfs/group
>> @@ -122,3 +122,4 @@
>>  118 auto quick snapshot metadata
>>  119 auto quick snapshot metadata qgroup
>>  120 auto quick snapshot metadata
>> +121 auto replace
>> --
>> 2.7.0
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe fstests" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
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diff mbox

Patch

diff --git a/tests/btrfs/121 b/tests/btrfs/121
new file mode 100755
index 000000000000..81b7deb047af
--- /dev/null
+++ b/tests/btrfs/121
@@ -0,0 +1,163 @@ 
+#! /bin/bash
+# FS QA Test 121
+#
+# This test verify the RAID1 reconstruction on the reappeared
+# device. By using the following steps:
+# Initialize a RAID1 with some data
+#
+# Re-mount RAID1 degraded with dev2 missing and write up to
+# half of the FS capacity.
+# Save md5sum checkpoint1
+#
+# Re-mount healthy RAID1
+#
+# Let balance re-silver.
+# Save md5sum checkpoint2
+#
+# Re-mount RAID1 degraded with dev1 missing
+# Save md5sum checkpoint3
+#
+# Verify if all three checkpoints match
+#
+#---------------------------------------------------------------------
+# Copyright (c) 2016 Oracle.  All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#---------------------------------------------------------------------
+#
+
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+here=`pwd`
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# real QA test starts here
+
+_supported_fs btrfs
+_supported_os Linux
+_require_scratch_nocheck
+_require_scratch_dev_pool 2
+
+# the mounted test dir prevent btrfs unload, we need to unmount
+_test_unmount
+_require_btrfs_unloadable
+
+_scratch_dev_pool_get 2
+
+dev1=`echo $SCRATCH_DEV_POOL | awk '{print $1}'`
+dev2=`echo $SCRATCH_DEV_POOL | awk '{print $2}'`
+
+dev1_sz=`blockdev --getsize64 $dev1`
+dev2_sz=`blockdev --getsize64 $dev2`
+# get min of both
+max_fs_sz=`echo -e "$dev1_sz\n$dev2_sz" | sort | head -1`
+max_fs_sz=$(( max_fs_sz/2 ))
+if [ $max_fs_sz -gt 1000000 ]; then
+	bs="1M"
+	count=$(( max_fs_sz/1000000 ))
+else
+	max_fs_sz=$(( max_fs_sz*2 ))
+	_notrun "Smallest dev size $max_fs_sz, Need at least 2M"
+fi
+
+echo >> $seqres.full
+echo "max_fs_sz=$max_fs_sz count=$count" >> $seqres.full
+echo "-----Initialize -----" >> $seqres.full
+_scratch_pool_mkfs "-mraid1 -draid1" >> $seqres.full 2>&1
+_scratch_mount >> $seqres.full 2>&1
+_run_btrfs_util_prog filesystem show
+dd if=/dev/zero of="$SCRATCH_MNT"/tf1 bs=$bs count=1 \
+					>>$seqres.full 2>&1
+count=$(( count-- ))
+echo "unmount" >> $seqres.full
+echo "clean btrfs ko" >> $seqres.full
+_scratch_unmount
+_reload_btrfs_ko
+
+
+echo >> $seqres.full
+echo "-----Write degraded mount fill upto $max_fs_sz bytes-----" >> $seqres.full
+echo
+echo "Write data with degraded mount"
+# Since we didn't run dev scan, btrfs kernel does not know
+# about the dev2
+# don't use _scratch_mount as we want to control
+# the device used for mounting.
+
+_mount -o degraded $dev1 $SCRATCH_MNT >>$seqres.full 2>&1
+_run_btrfs_util_prog filesystem show
+dd if=/dev/zero of="$SCRATCH_MNT"/tf2 bs=$bs count=$count \
+					>>$seqres.full 2>&1
+checkpoint1=`md5sum $SCRATCH_MNT/tf2`
+echo $checkpoint1 >> $seqres.full 2>&1
+_scratch_unmount
+echo "unmount" >> $seqres.full
+
+echo >> $seqres.full
+echo "-----Mount normal-----" >> $seqres.full
+echo
+echo "Mount normal after balance"
+_run_btrfs_util_prog device scan
+_scratch_mount >> $seqres.full 2>&1
+_run_btrfs_util_prog filesystem show
+echo >> $seqres.full
+_run_btrfs_util_prog balance start ${SCRATCH_MNT}
+
+checkpoint2=`md5sum $SCRATCH_MNT/tf2`
+echo $checkpoint2 >> $seqres.full 2>&1
+
+echo >> $seqres.full
+echo "-----Mount degraded but with other dev -----" >> $seqres.full
+echo
+echo "Mount degraded but with other dev"
+_scratch_unmount
+_reload_btrfs_ko
+_mount -o degraded $dev2 $SCRATCH_MNT >>$seqres.full 2>&1
+_run_btrfs_util_prog filesystem show
+checkpoint3=`md5sum $SCRATCH_MNT/tf2`
+echo $checkpoint3 >> $seqres.full 2>&1
+
+if [ "$checkpoint1" != "$checkpoint2" ]; then
+	echo $checkpoint1
+	echo $checkpoint2
+	_fail "Inital sum does not match with after balance"
+fi
+
+if [ "$checkpoint1" != "$checkpoint3" ]; then
+	echo $checkpoint1
+	echo $checkpoint3
+	_fail "Inital sum does not match with data on dev2 written by balance"
+fi
+
+_scratch_dev_pool_put
+_test_mount
+
+echo "Silence is golden"
+status=0
+exit
diff --git a/tests/btrfs/121.out b/tests/btrfs/121.out
new file mode 100644
index 000000000000..0728787d17bc
--- /dev/null
+++ b/tests/btrfs/121.out
@@ -0,0 +1,8 @@ 
+QA output created by 121
+
+Write data with degraded mount
+
+Mount normal after balance
+
+Mount degraded but with other dev
+Silence is golden
diff --git a/tests/btrfs/group b/tests/btrfs/group
index 90af8fc2d106..5c28a3ca0687 100644
--- a/tests/btrfs/group
+++ b/tests/btrfs/group
@@ -122,3 +122,4 @@ 
 118 auto quick snapshot metadata
 119 auto quick snapshot metadata qgroup
 120 auto quick snapshot metadata
+121 auto replace