注意：此问题之前已被关闭为非主题.你可以阅读
discussion.我在这里问的理由是：
>此驱动器位于赞比亚农村学校的离线内容缓存服务器中.
>服务器是从磁盘映像创建的,所有内容都是可替换的.
>它必须便宜,因为赞比亚学校的预算有限,而且会有很多.
>它也必须可靠,因为在不良道路上可能需要8小时才能更换.
>我不允许在这里询问什么驱动器不是“超便宜的垃圾”.
>因此,我们正在对符合这些标准的驱动器进行自己的研究和实验.
>我无法通过覆盖它们来修复坏扇区(自动重新分配)违背了我的假设,我想知道原因.
>我想也许一个安全删除可能会修复坏道,但在我废弃驱动器之前想要别人的意见.
>我以为我可能错过了可以预测失败的SMART数据.
这是一款金士顿240GB SSD磁盘,在网站上工作了大约3个月,突然发展出坏道：
smartctl 5.41 2011-06-09 r3365 [i686-linux-3.2.20-net6501-121115-1cw] (local build)
Copyright (C) 2002-11 by Bruce Allen,http://smartmontools.sourceforge.net
=== START OF INFORMATION SECTION ===
Device Model: KINGSTON SVP200S3240G
Serial Number: 50026B7228010E5C
LU WWN Device Id: 5 0026b7 228010e5c
Firmware Version: 502ABBF0
User Capacity: 240,057,409,536 bytes [240 GB]
Sector Size: 512 bytes logical/physical
Device is: Not in smartctl database [for details use: -P showall]
ATA Version is: 8
ATA Standard is: ACS-2 revision 3
Local Time is: Tue Mar 5 17:10:24 2013 CAT
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
General SMART Values:
Offline data collection status: (0x02) Offline data collection activity
was completed without error.
Auto Offline Data Collection: Disabled.
Self-test execution status: ( 0) The previous self-test routine completed
without error or no self-test has ever
been run.
Total time to complete Offline
data collection: ( 0) seconds.
Offline data collection
capabilities: (0x7b) SMART execute Offline immediate.
Auto Offline data collection on/off support.
Suspend Offline collection upon new
command.
Offline surface scan supported.
Self-test supported.
Conveyance Self-test supported.
Selective Self-test supported.
SMART capabilities: (0x0003) Saves SMART data before entering
power-saving mode.
Supports SMART auto save timer.
Error logging capability: (0x01) Error logging supported.
General Purpose Logging supported.
Short self-test routine
recommended polling time: ( 1) minutes.
Extended self-test routine
recommended polling time: ( 48) minutes.
Conveyance self-test routine
recommended polling time: ( 2) minutes.
SCT capabilities: (0x0021) SCT Status supported.
SCT Data Table supported.
SMART Attributes Data Structure revision number: 10
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
1 Raw_Read_Error_Rate 0x000f 084 084 050 Pre-fail Always - 10965286670575
5 Reallocated_Sector_Ct 0x0033 100 100 003 Pre-fail Always - 16
9 Power_On_Hours 0x0032 000 000 000 Old_age Always - 46823733462185
12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 127
171 Unknown_Attribute 0x0032 000 000 000 Old_age Always - 0
172 Unknown_Attribute 0x0032 000 000 000 Old_age Always - 0
174 Unknown_Attribute 0x0030 000 000 000 Old_age Offline - 131
177 Wear_Leveling_Count 0x0000 000 000 000 Old_age Offline - 1
181 Program_Fail_Cnt_Total 0x0032 000 000 000 Old_age Always - 0
182 Erase_Fail_Count_Total 0x0032 000 000 000 Old_age Always - 0
187 Reported_Uncorrect 0x0032 000 000 000 Old_age Always - 49900
194 Temperature_Celsius 0x0022 033 078 000 Old_age Always - 33 (Min/Max 21/78)
195 Hardware_ECC_Recovered 0x001c 120 120 000 Old_age Offline - 235163887
196 Reallocated_Event_Count 0x0033 100 100 003 Pre-fail Always - 16
201 Soft_Read_Error_Rate 0x001c 120 120 000 Old_age Offline - 235163887
204 Soft_ECC_Correction 0x001c 120 120 000 Old_age Offline - 235163887
230 Head_Amplitude 0x0013 100 100 000 Pre-fail Always - 100
231 Temperature_Celsius 0x0013 100 100 010 Pre-fail Always - 0
233 Media_Wearout_Indicator 0x0000 000 000 000 Old_age Offline - 363
234 Unknown_Attribute 0x0032 000 000 000 Old_age Always - 208
241 Total_LBAs_Written 0x0032 000 000 000 Old_age Always - 208
242 Total_LBAs_Read 0x0032 000 000 000 Old_age Always - 1001
SMART Error Log not supported
SMART Self-test Log not supported
SMART Selective self-test log data structure revision number 1
SPAN MIN_LBA MAX_LBA CURRENT_TEST_STATUS
1 0 0 Not_testing
2 0 0 Not_testing
3 0 0 Not_testing
4 0 0 Not_testing
5 0 0 Not_testing
Selective self-test flags (0x0):
After scanning selected spans,do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up,resume after 0 minute delay.
现在我在磁盘上的某些地方遇到了坏块：
root@iPad2:~# badblocks /dev/sda -v Checking blocks 0 to 234431063 Checking for bad blocks (read-only test): 8394752 done,1:15 elapsed 8394756 done,1:21 elapsed 8394757 done,1:23 elapsed 8394758 done,1:24 elapsed 8394759 done,1:27 elapsed ... 190882871one,29:49 elapsed 190882888one,29:53 elapsed 190882889one,29:54 elapsed 190882890one,29:56 elapsed 190882891one,29:58 elapsed done Pass completed,80 bad blocks found.
它们似乎是可重复的,并且自动重新分配失败,因此无法通过写入它们来修复它们：
root@iPad2:~# badblocks /dev/sda -wvf 8394756 8394756 /dev/sda is apparently in use by the system; badblocks forced anyway. Checking for bad blocks in read-write mode From block 8394756 to 8394756 Testing with pattern 0xaa: 8394756 done Reading and comparing: done Testing with pattern 0x55: done Reading and comparing: done Testing with pattern 0xff: done Reading and comparing: done Testing with pattern 0x00: done Reading and comparing: done Pass completed,1 bad blocks found.
我在系统日志中遇到这样的错误：
ata1.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0x0
ata1.00: irq_stat 0x40000000
ata1.00: failed command: READ FPDMA QUEUED
ata1.00: cmd 60/08:00:08:30:00/00:00:01:00:00/40 tag 0 ncq 4096 in
res 51/40:08:08:30:00/00:00:01:00:00/40 Emask 0x409 (media error) <F>
ata1.00: status: { DRDY ERR }
ata1.00: error: { UNC }
ata1.00: configured for UDMA/133
sd 0:0:0:0: [sda] Unhandled sense code
sd 0:0:0:0: [sda] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
sd 0:0:0:0: [sda] Sense Key : Medium Error [current] [descriptor]
Descriptor sense data with sense descriptors (in hex):
72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00
01 00 30 08
sd 0:0:0:0: [sda] Add. Sense: Unrecovered read error - auto reallocate failed
sd 0:0:0:0: [sda] CDB: Read(10): 28 00 01 00 30 08 00 00 08 00
end_request: I/O error,dev sda,sector 16789512
Buffer I/O error on device sda,logical block 2098689
ata1: EH complete
现在我不明白为什么自动重新分配在这个磁盘上失败了. smartctl输出对我来说都很好看.只有16个部门被重新分配,这一点并不多.我看不出这个驱动器拒绝重新分配扇区的任何正当理由.这种型号的SSD刚刚破损或设计糟糕吗？
笔记：
>根据金斯顿的文档,属性174是“意外断电”.
> 131意外断电非常糟糕.
>属性187(Reported_Uncorrect)是可能的最大值65535中的49900
>最高温度在78’C时非常高
金士顿在这个驱动器上隐藏了最多的interesting SMART counters.但是我们可以从属性196推断出备用扇区的数量.Reallocated_Event_Count,它具有以下规范化值的公式：
100 -(100* RBC / MRC) RBC = Retired Block Count (Grown) MRE = Maximum reallocation count
由于归一化值是100,这意味着RBC << MRE,因此我们无法用尽所有可用的部门进行重新分配.
解决方法
廉价的SSD似乎有严重的质量问题.您会发现许多用户对您的特定硬盘有问题.但是我认为供应商也在同一标签下销售不同的驱动器(例如与其他NAND芯片/控制器).因此每个驱动器可能表现不同.
SMART值不表示驱动器很快就会失效.根据我的经验,它是相同的：突然发生驱动器错误,然后磁盘发生故障.
你使用固态硬盘的原因是什么？我看到SSD的优势在于没有机械部件,因为它们防尘并且产生的热量更少.但是我也看到了很多缺点.
例如在繁忙的音量上可以快速达到对单个存储单元的写入次数,即使是耗损均衡也是如此.当您使用具有日记功能的文件系统时.
电子设备也受到高湿度或高温的影响 – 与传统硬盘驱动器相同.
为什么不使用更便宜的传统硬盘而且(如果不需要raid)将服务器与备用驱动器一起运送,直到它们需要作为替代品(已经存在于服务器机箱或安装在热插拔笼中,以便磁盘可以在不同的服务器中使用).然后他们可以通过现场或远程(如果可能)的脚本准备.
只要传统的硬盘没有通电,到目的地的运输就会很粗糙……
如果有多个学校服务器/永久客户端和可靠/冗余网络,则分布式文件系统也可以帮助创建故障安全缓存服务器(例如,通过使用glusterfs).
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