[gull] Write Amplification on SSD

[Blaise Vogel]

Bonjour,

Merci pour l'info, mais il semblerait que ce champ ne soit pas toujours renseigné:

root at A006T440:~# sed 's/^.*[Rr]ealloc.*\([sS]ector\|[bB]locks\).* \([0-9]\+\) *$/\2/p;d' <(smartctl -a /dev/sda)
root at A006T440:~# smartctl -a /dev/sda

=== START OF INFORMATION SECTION ===
Device Model:     SAMSUNG MZ7TD256HAFV-000L9
Serial Number:    S17LNSADA00826
LU WWN Device Id: 5 002538 500000000
Firmware Version: DXT02L5Q
User Capacity:    256'060'514'304 bytes [256 GB]
Sector Size:      512 bytes logical/physical
Rotation Rate:    Solid State Device
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   ACS-2, ATA8-ACS T13/1699-D revision 4c
SATA Version is:  SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Thu Feb 11 13:37:04 2016 CET
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

...
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  9 Power_On_Hours          0x0032   099   099   000    Old_age   Always       -       4180
 12 Power_Cycle_Count       0x0032   096   096   000    Old_age   Always       -       3135
175 Program_Fail_Count_Chip 0x0032   100   100   010    Old_age   Always       -       0
176 Erase_Fail_Count_Chip   0x0032   100   100   010    Old_age   Always       -       0
177 Wear_Leveling_Count     0x0013   096   096   005    Pre-fail  Always       -       46
178 Used_Rsvd_Blk_Cnt_Chip  0x0013   100   100   010    Pre-fail  Always       -       0
179 Used_Rsvd_Blk_Cnt_Tot   0x0013   100   100   010    Pre-fail  Always       -       0
180 Unused_Rsvd_Blk_Cnt_Tot 0x0013   100   100   010    Pre-fail  Always       -       6240
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
184 End-to-End_Error        0x0033   100   100   097    Pre-fail  Always       -       0
187 Reported_Uncorrect      0x0032   100   100   000    Old_age   Always       -       0
190 Airflow_Temperature_Cel 0x0032   070   059   000    Old_age   Always       -       30
195 Hardware_ECC_Recovered  0x001a   200   200   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0030   100   100   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x003e   253   253   000    Old_age   Always       -       0
233 Media_Wearout_Indicator 0x003a   199   199   000    Old_age   Always       -       364366
234 Unknown_Attribute       0x0012   100   100   000    Old_age   Always       -       0
235 Unknown_Attribute       0x0012   099   099   000    Old_age   Always       -       43
236 Unknown_Attribute       0x0012   099   099   000    Old_age   Always       -       14
237 Unknown_Attribute       0x0012   099   099   000    Old_age   Always       -       46
238 Unknown_Attribute       0x0012   100   100   000    Old_age   Always       -       0

SMART Error Log Version: 1
No Errors Logged
...

l'ID 5 est manquant !
Par contre le champ 180 Unused_Rsvd_Blk_Cnt_Tot pourrait être significatif, en cas de diminution. 
Pas documenté chez smartmoontools:
https://www.smartmontools.org/wiki/TocDoc#SMARTAttributes

Par contre ici:
http://opentsdb.net/docs/build/html/user_guide/utilities/tcollector.html

Donc pour les Samsung, à monitorer ;-)

Blaise Vogel