CEPH : SSD wearout

[TwiX]

HI,

My 'oldest' prx ceph cluster is based on samsung SM863a drives.
After 3 years, wearout for some drives is less than "88% remaining".

I don't know if these values are safe enough.
Under what kind of Wearout value it is recommended to change the SSD drive ?

Thanks !

 

[TwiX]

Here are the S.M.A.R.T values :
90% remaining for this drive
You can notice that GUI indicates wrong wearout.

 

[TwiX]

Right wearout values are also confirmed by DELL idrac :

 

[Alwin]

90% remaining for this drive
You can notice that GUI indicates wrong wearout.

It depends on the observed attribute. Every hardware vendor uses slightly different attributes for it.

 

[dcsapak]

what kind of drive is it? (vendor/model)
by default we use the 'media wearout indicator field' which is at 99 for your disk

 

[dcsapak]

ok did now see that those are samsung disks...

for those we usually use the (correct) field id 177, but it seems that your controller hides the vendor info from us, so we do not detect that they are samsung disks and use field 233

 

[TwiX]

Hi,

Unfortunately, the right values are provided by another attribute for me. CF values provided by Dell idrac => 90% remaining

here is the result of 'smartctl -a /dev/sda'

smartctl -a /dev/sda
smartctl 6.6 2016-05-31 r4324 [x86_64-linux-4.15.18-9-pve] (local build)
Copyright (C) 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Device Model:     MZ7KM480HMHQ0D3
Serial Number:    S3BUNX0J617514
LU WWN Device Id: 5 002538 c4069aa3b
Add. Product Id:  DELL(tm)
Firmware Version: GD53
User Capacity:    480,103,981,056 bytes [480 GB]
Sector Size:      512 bytes logical/physical
Rotation Rate:    Solid State Device
Form Factor:      2.5 inches
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   ACS-3 T13/2161-D revision 5
SATA Version is:  SATA 3.2, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Tue Feb 11 12:31:10 2020 CET
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:                ( 2100) seconds.
Offline data collection
capabilities:                    (0x5b) SMART execute Offline immediate.
                                        Auto Offline data collection on/off support.
                                        Suspend Offline collection upon new
                                        command.
                                        Offline surface scan supported.
                                        Self-test supported.
                                        No 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:        (   2) minutes.
Extended self-test routine
recommended polling time:        (  35) minutes.
SCT capabilities:              (0x003d) SCT Status supported.
                                        SCT Error Recovery Control supported.
                                        SCT Feature Control supported.
                                        SCT Data Table supported.

SMART Attributes Data Structure revision number: 1
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x001a   200   200   000    Old_age   Always       -       0
  5 Reallocated_Sector_Ct   0x0033   100   100   010    Pre-fail  Always       -       0
  9 Power_On_Hours          0x0032   095   095   000    Old_age   Always       -       21094
 12 Power_Cycle_Count       0x0032   099   099   000    Old_age   Always       -       18
 13 Read_Soft_Error_Rate    0x001a   200   200   000    Old_age   Always       -       0
177 Wear_Leveling_Count     0x0013   090   090   005    Pre-fail  Always       -       3559
179 Used_Rsvd_Blk_Cnt_Tot   0x0013   100   100   010    Pre-fail  Always       -       0
180 Unused_Rsvd_Blk_Cnt_Tot 0x0012   100   100   000    Old_age   Always       -       2754
181 Program_Fail_Cnt_Total  0x0032   100   100   000    Old_age   Always       -       0
182 Erase_Fail_Count_Total  0x0032   100   100   000    Old_age   Always       -       0
184 End-to-End_Error        0x0033   100   100   097    Pre-fail  Always       -       0
194 Temperature_Celsius     0x0022   070   057   000    Old_age   Always       -       30
195 Hardware_ECC_Recovered  0x001a   100   100   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0030   100   100   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x003e   100   100   000    Old_age   Always       -       0
201 Unknown_SSD_Attribute   0x0033   100   100   001    Pre-fail  Always       -       0
202 Unknown_SSD_Attribute   0x0033   100   100   010    Pre-fail  Always       -       0
233 Media_Wearout_Indicator 0x0032   099   099   000    Old_age   Always       -       757812890653
235 Unknown_Attribute       0x0012   099   099   000    Old_age   Always       -       8
242 Total_LBAs_Read         0x0032   099   099   000    Old_age   Always       -       284999000777
243 Unknown_Attribute       0x0032   100   100   000    Old_age   Always       -       0
244 Unknown_Attribute       0x0032   100   100   000    Old_age   Always       -       0
245 Unknown_Attribute       0x003a   090   090   000    Old_age   Always       -       90
246 Unknown_Attribute       0x0032   100   100   000    Old_age   Always       -       65535
247 Unknown_Attribute       0x0032   100   100   000    Old_age   Always       -       65535
248 Unknown_Attribute       0x0032   100   100   000    Old_age   Always       -       65535
251 Unknown_Attribute       0x0032   100   100   000    Old_age   Always       -       3729872403968

SMART Error Log Version: 1
No Errors Logged

SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
# 1  Short offline       Completed without error       00%         3         -
# 2  Extended offline    Completed without error       00%         2         -

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
  255        0    65535  Read_scanning was completed without error
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.

 

[TwiX]

ok did now see that those are samsung disks...

for those we usually use the (correct) field id 177, but it seems that your controller hides the vendor info from us, so we do not detect that they are samsung disks and use field 233

It doesn't matter
I know what to check.
But before buying lots of SSD in order to replace them, I want to know the wearout value where the drive must be replaced.

 

[Alwin]

Well, when they are dead.
https://blog.okmeter.io/real-world-ssd-wearout-a3396a35c663
https://www.dell.com/support/articl...y-do-solid-state-devices-ssd-wear-out?lang=en

 

[TwiX]

Thanks for these urls.
So with still more than 80 % remaining, I have 2 or 3 years before replacing them I guess.

it decreases by 1% every 2 months.

 

[Alwin]

Only the wear level considered, yes. But they might fail because of other reasons, eg. SSD controller failure, overheating, SSD cache defect, ... . The best part of having Ceph run on them, you can replace them without any interruption for Ceph. Best buy them from different batches, to decrease the likelihood of multiple failing SSDs.

 

[brucexx]

Nice graph , I assume this is Zabbix. Did you have to install the agent on proxmox nodes to get that info from SMART ?

BTW my SSD on Ceph installed on Proxmox say N/A under Wearout. Not sure if this is a bug or they say N/A because there is no wearout so far. I thought with no wearout it would say 100% remaining. Dell's iDrac controller say that this info is unavailable.

The drive says that the SMART support is enabled gives me "Percentage used endurance indicator: 0%" which I like but also "No Self-Test have been logged" in the end. Should the proxmox run the SMART test or iDrac - does anybody know ? That's probably why it sayd N/A as there was no SMART test run on it.



Thank you

 

[TwiX]

Hi,

You're right this is Zabbix

I get wearout values via SNMP through Dell idrac.
I created an item under the disk discovery section.
It works for idrac 8 or newer.
The related OID is 1.3.6.1.4.1.674.10892.5.5.1.20.130.4.1.49.{#SNMPINDEX}

for HDD returned value is 255
http://oidref.com/1.3.6.1.4.1.674.10892.5.5.1.20.130.4.1.49

You could also get wearout via smartctl I guess

 

[brucexx]

Thx, will give it a try.