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SSD

tip
  • SSD 容量越大寿命越久
  • SSD 不需要 defragment
  • fstrim 可能增加寿命
ssd specSATA SSDM.2 SATAM.2 PCIe/NVMe
interfaceSATAM.2/SATAM.2/PCIe
feature取代 HDD更轻薄更快
write560 MB/s560 MB/s3400 MB/s
read510 MB/s510 MB/s3400 MB/s

寿命​

abbr.stand forcn
TBWTotalBytes Written总写入量
TBWTB Written
DWPDDrive Write Per Day每日写入量
MTBFMean time between failures平均故障间隔时间
WAFWrite Amplification Factor写放大因子
P/EProgram / Erase
RBERRaw Bit Error Rate原始位错误率
  • TBW = SSD Capacity * NAND P/E Cycles / WAF * 1024
    • 不考虑 WAF - 如果 100G, PE = 3000 则 TBW=300T
    • 预留 15% TBW - 低于该数值应该考虑更换
  • DWPD = TBW * 1024 / SSD Capacity * 保固期限
  • MTBF = 1/失效率
  • WAF
    • 例如 8k page, 写 512 byte 则 WAF = 8K/512=16
    • 个人通常 2-4，企业通常 10
    • 随机写引发的 GC 和移动
  • NAND P/E Cycles
    • MLC 128GB SSD, NAND P/E cycles = 3000
  • JESD219A Solid-State Drive
    • TWB 计算标准

FAQ

  • RAPID Mode - Realtime Accelerated Processing of I/O Data
    • 三星 EVO 专利技术
  • SRT - Smart Response Technology
    • Intel 技术 - 使用 SSD 加速 HDD
  • Samsung 850 PRO > Samsung 850 EVO > Samsung 850
  • fast write-back cache
    • SSD 的写入缓存，当写入量超过时可能会变得很慢

监控

Samsung​

  • 三星
    • Total_LBAs_Written
      • value*512=总写入
    • 总写入/Power_On_Hours=平均每小时写入速率
    • Wear_Leveling_Count
SMART/Health Information (NVMe Log 0x02)
Critical Warning:                   0x00
Temperature:                        50 Celsius
Available Spare:                    100%
Available Spare Threshold:          5%
Percentage Used:                    0%
Data Units Read:                    1,493,974 [764 GB]
Data Units Written:                 1,670,589 [855 GB]
Host Read Commands:                 12,129,225
Host Write Commands:                7,321,092
Controller Busy Time:               22
Power Cycles:                       69
Power On Hours:                     7
Unsafe Shutdowns:                   45
Media and Data Integrity Errors:    0
Error Information Log Entries:      2
Warning  Comp. Temperature Time:    0
Critical Comp. Temperature Time:    0
Thermal Temp. 1 Transition Count:   1
Thermal Temp. 1 Total Time:         22

Intel​

  • Host_Writes_32MIB
  • Media_Wearout_Indicator
    • 健康度，100 -> 001
    • MWI
    • 过低时过保