1 編寫目的
在如今大資料的環境中，磁盤的性能和穩定性是非常重要的一個業務因素。在Linux系統中，smartctl是較為常用的磁盤檢測工具。
本文基于Linux系統中smartctl進行分析，目的在于說明相關工具的使用，并對SMART(Self-Monitoring, Analysis and Reporting Technology)做一些分析。
2 術語、定義和縮略語
2.1 術語、定義
本文使用的專用術語、定義，見表2.1。
表2.1
| 術語/定義 | 含義 |
| SMART | Self-Monitoring, Analysis and Reporting Technology |
2.2 縮略語
本檔案應用了以下縮略語，見表2.2。
表2.2
| 縮略語 | 原 文 | 中文含義 |
| SMART | Self-Monitoring, Analysis and Reporting Technology | 自監察分析及報告技術 |
3 smartctl
smartctl是smartmontools-5.38-2.el5 rpm中的一個指令行工具，可以執行SMART任務：列印SMART self-test和error報告，開啟或關閉SMART自動測試，觸發磁盤self-test。
文法：
smartctl [options] device
device：
“/dev/hd[a-t]” IDE/ATA 磁盤
“/dev/sd[a-z]” SCSI devices磁盤。注意，對于SATA磁盤，由于是通過libata
庫來通路，是以要增加參數“-d ata”。
3.1 [options]：
參數按照不同的類型來分類。
3.1.1 顯示資訊 參數：
-h 幫助資訊
-V 版本資訊
-i 列印基本資訊（磁盤裝置号、序列号、固件版本…）
-a 列印磁盤所有的SMART資訊
3.1.2 運作時行為 參數：
-q TYPE 指定輸出的安靜模式。
TYPE可以有3種選擇：
eorsonly 隻列印錯誤日志。
slent 有任何列印。
nserial 不列印序列号
-d TYPE 指定磁盤的類型。如果沒有指定，smartctl會根據磁盤的名字來
猜測磁盤類型。
-T TYPE 指定當發生錯誤時，smartctl的容忍程度，是否繼續運作。
TYPE可以有4種選擇：
conservative 一有錯就會退出
normal 如果必須支援的SMART指令失敗，則退出
permissive 忽略一次必須支援的SMART指令失敗
verypermissive 忽略所有必須支援的SMART指令失敗
-b TYPE 指定當發生校驗錯誤時，smartctl的動作。
TYPE有3種選擇：
warn 發出警告，繼續執行
exit 退出smartctl
ignore 不發出告警，繼續執行
-r TYPE smartmontools開發人員相關。
-n POWERMODE 指定當磁盤處于節能模式時，smartctl是否繼續檢查，
預設是不檢查。
POWERMODE有4種選擇：
never 檢查
sleep 除了sleep模式，檢查。
standby 除了sleep或standby模式，檢查。
idle 除了sleep或standby或idle模式，見車。
3.1.3 SMART功能開關 參數：
-s on/off 打開或關閉磁盤的SMART功能
-o on/off 打開或關閉SMART自動離線檢測，該功能每4小時就會自動掃描磁盤是
否有缺陷。
-S on/off 打開或關閉“自動儲存廠商指定屬性”功能。
3.1.4 SMART 讀和顯示資料 參數
-H 報告磁盤的是否健康。如果報告不健康，則說明磁盤已經損壞或會在24小時
内損壞。
-c 顯示磁盤支援的普通SMART功能，以及這些功能目前的狀态。
-A 顯示磁盤支援的廠商指定SMART特性。這些特性的編号從1-253，并且有指
定的名字。
-l TYPE 指定顯示的log類型。
TYPE有4種選擇：
error 隻顯示error log。
selftest 隻顯示selftest log
selective 隻顯示selective self-test log
directory 隻顯示Log Directory
-v N,OPTION 顯示廠商指定SMART特性N時，使用廠商相關的顯示方式。
-F TYPE 設定smartctl的行為，當出現一些已知但還沒有解決的硬體或軟體bug時，
smartctl應該怎麼做。
-P TYPE 設定smartctl是否對磁盤使用資料庫中已有的參數。
3.1.5 SMART 離線測試、自測試 參數
-t TEST 立刻執行測試，可以和-C參數一起使用。
TEST可以有以下幾個選擇：
offline 離線測試。可以在挂載檔案系統的磁盤上使用
short 短時間測試。可以在挂載檔案系統的磁盤上使用。
long 長時間測試。可以在挂載檔案系統的磁盤上使用。
conveyance [ATA only]傳輸zi測試。可以在挂載檔案系統的磁盤上使用。
select, N-M
select, N+SIZE [ATA only]有選擇性測試，測試磁盤的部分LBA。N表示
LBA編号，M表示結束LBA編号，SIZE表示測試的LBA
範圍。
-C 在captive模式下運作測試。
注意：（1）-C必須配合-t一起使用，但如果是-t offline，則-C不生效。
（2）-C會使得磁盤很忙，是以最好是在沒有挂載檔案系統的磁盤上使用。
-X 中斷no-captive模式下運作的測試。
3.2 常用example
3.2.1 檢視目前整體健康狀态
檢視/dev/sda目前整體監控狀态。PASSED表示健康，否則意味着磁盤已經故障，或很快就會發生故障。
smartctl -H /dev/sda
3.2.2 檢視所有資訊
列印/dev/sda所有的SMART資訊。
martctl -a /dev/sda
相當于依次執行：
smartctl –i /dev/sda
smartctl -c /dev/sda
smartctl -A /dev/sda
smartctl -l error /dev/sda
smartctl -l selftest /dev/sda
smartctl -l selective /dev/sda
3.2.3 開/關SMART功能
打開或關閉/dev/sda 的SMART功能。
smartctl -s on/off /dev/sda
檢視目前SMART功能是否開啟，可以使用 –i 參數。
smartctl -i /dev/sda
3.2.4 離線測試
對/dev/sda進行離線測試，它的結果主要用來更新SMART 屬性。
smartctl -t offline /dev/sda
3.2.5 短時間測試
對/dev/sda進行短時間測試。
smartctl -t short /dev/sda
3.2.5.1 觀察測試進度
通過-c 參數，可以觀察到測試的進度：
# smartctl -c /dev/sda
…
Self-test execution status: ( 242) Self-test routine in progress…
20% of test remaining.
…
3.2.5.2 觀察測試結果
通過-l selftest 參數，可以看到/dev/sda測試的結果記錄：
“#1”代表的那一次測試，Completed without error表示完成，沒有錯誤。
“#2”代表的那一次測試，Aborted by host表示測試被使用者終止，還有90%沒有完成。
# smartctl -l selftest /dev/sda
…
Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error
# 1 Short offline Completed without error 00% 9535 -
# 2 Extended offline Aborted by host 90% 9534 -
…
3.2.6 檢視SMART屬性值
通過-A參數，可以看到/dev/sda SMART屬性值。
smartctl -A /dev/sda
3.4 SMART 屬性
使用smartctl -A /dev/sda能看到很多磁盤的SMART 屬性，可以知道磁盤是否健康。
下面是一個清單，可以知道每個屬性的具體含義：
| ID | Hex | Attribut name | Description |
| 01 | 0x01 | Read Error Rate | (Vendor specific raw value.) Stores data related to the rate of hardware read errors that occurred when reading data from a disk surface. The raw value has different structure for different vendors and is often not meaningful as a decimal number. |
| 02 | 0x02 | Throughput Performance | Overall (general) throughput performance of a hard disk drive. If the value of this attribute is decreasing there is a high probability that there is a problem with the disk. |
| 03 | 0x03 | Spin-Up Time | Average time of spindle spin up (from zero RPM to fully operational [millisecs]). |
| 04 | 0x04 | Start/Stop Count | A tally of spindle start/stop cycles. The spindle turns on, and hence the count is increased, both when the hard disk is turned on after having before been turned entirely off (disconnected from power source) and when the hard disk returns from having previously been put to sleep mode. |
| 05 | 0x05 | Reallocated Sectors Count | Count of reallocated sectors. When the hard drive finds a read/write/verification error, it marks that sector as “reallocated” and transfers data to a special reserved area (spare area). This process is also known as remapping, and reallocated sectors are called “remaps”. The raw value normally represents a count of the bad sectors that have been found and remapped. Thus, the higher the attribute value, the more sectors the drive has had to reallocate. This allows a drive with bad sectors to continue operation; however, a drive which has had any reallocations at all is significantly more likely to fail in the near future.[2]While primarily used as a metric of the life expectancy of the drive, this number also affects performance. As the count of reallocated sectors increases, the read/write speed tends to become worse because the drive head is forced to seek to the reserved area whenever a remap is accessed. A workaround which will preserve drive speed at the expense of capacity is to create a disk partition over the region which contains remaps and instruct the operating system to not use that partition. |
| 06 | 0x06 | Read Channel Margin | Margin of a channel while reading data. The function of this attribute is not specified. |
| 07 | 0x07 | Seek Error Rate | (Vendor specific raw value.) Rate of seek errors of the magnetic heads. If there is a partial failure in the mechanical positioning system, then seek errors will arise. Such a failure may be due to numerous factors, such as damage to a servo, or thermal widening of the hard disk. The raw value has different structure for different vendors and is often not meaningful as a decimal number. |
| 08 | 0x08 | Seek Time Performance | Average performance of seek operations of the magnetic heads. If this attribute is decreasing, it is a sign of problems in the mechanical subsystem. |
| 09 | 0x09 | Power-On Hours (POH) | Count of hours in power-on state. The raw value of this attribute shows total count of hours (or minutes, or seconds, depending on manufacturer) in power-on state. |
| 10 | 0x0A | Spin Retry Count | Count of retry of spin start attempts. This attribute stores a total count of the spin start attempts to reach the fully operational speed (under the condition that the first attempt was unsuccessful). An increase of this attribute value is a sign of problems in the hard disk mechanical subsystem. |
| 11 | 0x0B | Recalibration Retries orCalibration Retry Count | This attribute indicates the count that recalibration was requested (under the condition that the first attempt was unsuccessful). An increase of this attribute value is a sign of problems in the hard disk mechanical subsystem. |
| 12 | 0x0C | Power Cycle Count | This attribute indicates the count of full hard disk power on/off cycles. |
| 13 | 0x0D | Soft Read Error Rate | Uncorrected read errors reported to the operating system. |
| 180 | 0xB4 | Unused Reserved Block Count Total | “Pre-Fail” Attribute used at least in HP devices. |
| 183 | 0xB7 | SATA Downshift Error Count | Western Digital and Samsung attribute. |
| 184 | 0xb8 | End-to-End error / IOEDC | This attribute is a part of Hewlett-Packard’s SMART IV technology, as well as part of other vendors’ IO Error Detection and Correction schemas, and it contains a count of parity errors which occur in the data path to the media via the drive’s cache RAM. |
| 185 | 0xB9 | Head Stability | Western Digital attribute. |
| 186 | 0xBA | Induced Op-Vibration Detection | Western Digital attribute. |
| 187 | 0xBB | Reported Uncorrectable Errors | The count of errors that could not be recovered using hardware ECC . |
| 188 | 0xBC | Command Timeout | The count of aborted operations due to HDD timeout. Normally this attribute value should be equal to zero and if the value is far above zero, then most likely there will be some serious problems with power supply or an oxidized data cable. |
| 189 | 0xBD | High Fly Writes | HDD producers implement a Fly Height Monitor that attempts to provide additional protections for write operations by detecting when a recording head is flying outside its normal operating range. If an unsafe fly height condition is encountered, the write process is stopped, and the information is rewritten or reallocated to a safe region of the hard drive. This attribute indicates the count of these errors detected over the lifetime of the drive. This feature is implemented in most modern Seagate drives and some of Western Digital’s drives, beginning with the WD Enterprise WDE18300 and WDE9180 Ultra2 SCSI hard drives, and will be included on all future WD Enterprise products. |
| 190 | 0xBE | Airflow Temperature (WDC) resp.Airflow Temperature Celsius (HP) | Airflow temperature on Western Digital HDs (Same as temp. [C2], but current value is 50 less for some models. Marked as obsolete.) |
| 191 | 0xBF | G-sense Error Rate | The count of errors resulting from externally-induced shock & vibration. |
| 192 | 0xC0 | Power-off Retract Countor Emergency Retract Cycle Count(Fujitsu) | Count of times the heads are loaded off the media. Heads can be unloaded without actually powering off. |
| 193 | 0xC1 | Load Cycle Count orLoad/Unload Cycle Count(Fujitsu) | Count of load/unload cycles into head landing zone position. The typical lifetime rating for laptop (2.5-in) hard drives is 300,000 to 600,000 load cycles. Some laptop drives are programmed to unload the heads whenever there has not been any activity for about five seconds.Many Linux installations write to the file system a few times a minute in the background. As a result, there may be 100 or more load cycles per hour, and the load cycle rating may be exceeded in less than a year |
| 194 | 0xC2 | Temperatureresp.Temperature Celsius | Current internal temperature. |
| 195 | 0xC3 | Hardware ECC Recovered | (Vendor specific raw value.) The raw value has different structure for different vendors and is often not meaningful as a decimal number. |
| 196 | 0xC4 | Reallocation Event Count | Count of remap operations. The raw value of this attribute shows the total count of attempts to transfer data from reallocated sectors to a spare area. Both successful & unsuccessful attempts are counted. |
| 197 | 0xC5 | Current Pending Sector Count | Count of “unstable” sectors (waiting to be remapped, because of read errors). If an unstable sector is subsequently read successfully, this value is decreased and the sector is not remapped. Read errors on a sector will not remap the sector (since it might be readable later); instead, the drive firmware remembers that the sector needs to be remapped, and remaps it the next time it’s written. |
| 198 | 0xC6 | Uncorrectable Sector Countor Offline Uncorrectableor Off-Line Scan Uncorrectable Sector Count | The total count of uncorrectable errors when reading/writing a sector. A rise in the value of this attribute indicates defects of the disk surface and/or problems in the mechanical subsystem. |
| 199 | 0xC7 | UltraDMA CRC Error Count | The count of errors in data transfer via the interface cable as determined by ICRC (Interface Cyclic Redundancy Check). |
| 200 | 0xC8 | Multi-Zone Error Rate | The count of errors found when writing a sector. The higher the value, the worse the disk’s mechanical condition is. |
| 200 | 0xC8 | Write Error Rate (Fujitsu) | The total count of errors when writing a sector. |
| 201 | 0xC9 | Soft Read Error Rate or TA Counter Detected | Count of off-track errors. |
| 202 | 0xCA | Data Address Mark errorsor TA Counter Increased | Count of Data Address Mark errors (or vendor-specific). |
| 203 | 0xCB | Run Out Cancel | Count of ECC errors |
| 204 | 0xCC | Soft ECC Correction | Count of errors corrected by software ECC |
| 205 | 0xCD | Thermal Asperity Rate (TAR) | Count of errors due to high temperature. |
| 206 | 0xCE | Flying Height | Height of heads above the disk surface. A flying height that’s too low increases the chances of a head crash while a flying height that’s too high increases the chances of a read/write error. |
| 207 | 0xCF | Spin High Current | Amount of surge current used to spin up the drive. |
| 208 | 0xD0 | Spin Buzz | Count of buzz routines needed to spin up the drive due to insufficient power. |
| 209 | 0xD1 | Offline Seek Performance | Drive’s seek performance during its internal tests. |
| 210 | 0xD2 | Unkonw | (found in a Maxtor 6B200M0 200GB and Maxtor 2R015H1 15GB disks) |
| 211 | 0xD3 | Vibration During Write | Vibration During Write |
| 212 | 0xD4 | Shock During Write | Shock During Write |
| 220 | 0xDC | Disk Shift | Distance the disk has shifted relative to the spindle (usually due to shock or temperature). Unit of measure is unknown. |
| 222 | 0xDE | Loaded Hours | Time spent operating under data load (movement of magnetic head armature) |
| 223 | 0xDF | Load/Unload Retry Count | Count of times head changes position. |
| 224 | 0xE0 | Load Friction | Resistance caused by friction in mechanical parts while operating. |
| 225 | 0xE1 | Load/Unload Cycle Count | Total count of load cycles |
| 226 | 0xE2 | Load ‘In’-time | Total time of loading on the magnetic heads actuator (time not spent in parking area). |
| 227 | 0xE3 | Torque Amplification Count | Count of attempts to compensate for platter speed variations |
| 228 | 0xE4 | Power-Off Retract Cycle | The count of times the magnetic armature was retracted automatically as a result of cutting power. |
| 230 | 0xE6 | GMR Head Amplitude | Amplitude of “thrashing” (distance of repetitive forward/reverse head motion) |
| 231 | 0xE7 | Temperature | Drive Temperature |
| 232 | 0xE8 | Endurance Remaining | Number of physical erase cycles completed on the drive as a percentage of the maximum physical erase cycles the drive is designed to endure |
| 232 | 0xE8 | Available Reserved Space | Intel SSD reports the number of available reserved space as a percentage of reserved space in a brand new SSD. |
| 233 | 0xE9 | Power-On Hours | Number of hours elapsed in the power-on state. |
| 233 | 0xE9 | Media Wearout Indicator | Intel SSD reports a normalized value of 100 (when the SSD is new) and declines to a minimum value of 1. It decreases while the NAND erase cycles increase from 0 to the maximum-rated cycles. |
| 240 | 0xF0 | Head Flying Hours | Time while head is positioning |
| 240 | 0xF0 | Transfer Error Rate(Fujitsu) | Count of times the link is reset during a data transfer. |
| 241 | 0xF1 | Total LBAs Written | Total count of LBAs written |
| 242 | 0xF2 | Total LBAs Read | Total count of LBAs read. Some S.M.A.R.T. utilities will report a negative number for the raw value since in reality it has 48 bits rather than 32. |
| 250 | 0xFA | Read Error Retry Rate | Count of errors while reading from a disk |
| 254 | 0xFE | Free Fall Protection | ount of “Free Fall Events” detected |
3.5 SMART self-test
使用smartctl –t offline/short/long 可以指定磁盤進行自測。
offline：
這個是預設的自測。
short：
短時自測的目的是快速确認磁盤是否故障。
測試過程有很多項目，都是磁盤廠商自定義的，比如下面的項目：
a) 電氣測試項目，測試磁盤内部的電路。具體測試細節有磁盤廠商自己指定，比如：
A) 緩存測試。
B) 讀、寫電路測試。
C) 讀、寫磁頭測試。
b) 尋道、伺服測試項目，測試磁盤在資料磁道上的尋找和伺服能。
c) 讀、校驗測試項目，測試磁盤對部分或全盤的讀能力。
long：
稱為擴充的自測試。測試的項目和short類型，但是時間長得多
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