Date: Fri, 8 Dec 2017 16:57:23 -0500 From: Mike Tancsa <mike@sentex.net> To: freebsd-questions <freebsd-questions@freebsd.org> Subject: zfs mirror and unequal writes Message-ID: <d9f8be97-7a6b-13fd-eb33-9d37c5dc7c43@sentex.net>
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I was reading up on SSD life spans and decided to take a quick look at
how many TBW my disks have gone through. Looking at one box I was really
surprised at the uneven amount of data written
0{backup4}# smartctl -a /dev/ada0 | grep LBAs
241 Total_LBAs_Written 0x0032 099 099 000 Old_age Always
- 21004341355
0{backup4}# smartctl -a /dev/ada1 | grep LBAs
241 Total_LBAs_Written 0x0032 099 099 000 Old_age Always
- 413475182465
0{backup4}#
I was quite surprised that there were WAY more writes to one disk that
the other. Give these are zfs mirrors, one says 192TB writes and the
other is 10TB ?!?!?!
They were installed at the same time
1{backup4}# smartctl -a /dev/ada0 | grep Power_On
9 Power_On_Hours 0x0032 094 094 000 Old_age Always
- 29445
0{backup4}# smartctl -a /dev/ada1 | grep Power_On
9 Power_On_Hours 0x0032 094 094 000 Old_age Always
- 29275
0{backup4}#
Any ideas what might be going on ? The Wear_Leveling_Count seems out of
whack too, although I guess sort of expected ?
0{backup4}# smartctl -a /dev/ada1 | head
smartctl 6.4 2015-06-04 r4109 [FreeBSD 10.4-STABLE amd64] (local build)
Copyright (C) 2002-15, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Samsung based SSDs
Device Model: Samsung SSD 840 PRO Series
Serial Number: S1ANNSADB96894E
LU WWN Device Id: 5 002538 5a0164a23
Firmware Version: DXM05B0Q
User Capacity: 128,035,676,160 bytes [128 GB]
141{backup4}# smartctl -a /dev/ada0 | head
smartctl 6.4 2015-06-04 r4109 [FreeBSD 10.4-STABLE amd64] (local build)
Copyright (C) 2002-15, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Samsung based SSDs
Device Model: Samsung SSD 840 PRO Series
Serial Number: S1ANNSADB82440E
LU WWN Device Id: 5 002538 5a015e935
Firmware Version: DXM05B0Q
User Capacity: 128,035,676,160 bytes [128 GB]
141{backup4}#
and
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE
UPDATED WHEN_FAILED RAW_VALUE
5 Reallocated_Sector_Ct 0x0033 100 100 010 Pre-fail Always
- 0
9 Power_On_Hours 0x0032 094 094 000 Old_age Always
- 29275
12 Power_Cycle_Count 0x0032 099 099 000 Old_age Always
- 49
177 Wear_Leveling_Count 0x0013 008 008 000 Pre-fail Always
- 3332
179 Used_Rsvd_Blk_Cnt_Tot 0x0013 100 100 010 Pre-fail Always
- 0
181 Program_Fail_Cnt_Total 0x0032 100 100 010 Old_age Always
- 0
182 Erase_Fail_Count_Total 0x0032 100 100 010 Old_age Always
- 0
183 Runtime_Bad_Block 0x0013 100 100 010 Pre-fail Always
- 0
187 Uncorrectable_Error_Cnt 0x0032 100 100 000 Old_age Always
- 0
190 Airflow_Temperature_Cel 0x0032 067 062 000 Old_age Always
- 33
195 ECC_Error_Rate 0x001a 200 200 000 Old_age Always
- 0
199 CRC_Error_Count 0x003e 100 100 000 Old_age Always
- 0
235 POR_Recovery_Count 0x0012 099 099 000 Old_age Always
- 38
241 Total_LBAs_Written 0x0032 099 099 000 Old_age Always
- 413482348777
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE
UPDATED WHEN_FAILED RAW_VALUE
5 Reallocated_Sector_Ct 0x0033 100 100 010 Pre-fail Always
- 0
9 Power_On_Hours 0x0032 094 094 000 Old_age Always
- 29445
12 Power_Cycle_Count 0x0032 099 099 000 Old_age Always
- 51
177 Wear_Leveling_Count 0x0013 093 093 000 Pre-fail Always
- 246
179 Used_Rsvd_Blk_Cnt_Tot 0x0013 100 100 010 Pre-fail Always
- 0
181 Program_Fail_Cnt_Total 0x0032 100 100 010 Old_age Always
- 0
182 Erase_Fail_Count_Total 0x0032 100 100 010 Old_age Always
- 0
183 Runtime_Bad_Block 0x0013 100 100 010 Pre-fail Always
- 0
187 Uncorrectable_Error_Cnt 0x0032 100 100 000 Old_age Always
- 0
190 Airflow_Temperature_Cel 0x0032 067 062 000 Old_age Always
- 33
195 ECC_Error_Rate 0x001a 200 200 000 Old_age Always
- 0
199 CRC_Error_Count 0x003e 099 099 000 Old_age Always
- 92
235 POR_Recovery_Count 0x0012 099 099 000 Old_age Always
- 39
241 Total_LBAs_Written 0x0032 099 099 000 Old_age Always
- 21004655923
--
-------------------
Mike Tancsa, tel +1 519 651 3400
Sentex Communications, mike@sentex.net
Providing Internet services since 1994 www.sentex.net
Cambridge, Ontario Canada http://www.tancsa.com/
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