Samsung SSDs a right ashift size for ZFS pool?

[Dunuin]

CrystalDiskMark shows the same stuff, it just doesn't interpert the raw values as here is no DB backing the needed information how to do that. If you got the datasheet (if the manufacturer published that at all...Intel for example does) you could convert that raw value showed in CDM to human readable values.
But most important are the differences between "current" (aka "VALUE" in smartctl) and "threshhold". "current" is the current health state and "threshold" is the value that is alarming when "currents" gets below it. Here the "Wear Leveling Count" of 95% and 98% is good, so I would get them if you can't find something better.
Another point to look at is how much TBW the disk is rated for and how much CDM is reporting that it has written. So 11TB written to a 170TB TBW SSD, and 62TB written to a 350 TB TBW SSD.

Postage is a bit annoying but the price for the SSDs itself isn't bad.

Datasheets:
https://www.compuram.de/documents/datasheet/PM863_SAMSUNG.pdf

 

[zecas]

CrystalDiskMark shows the same stuff, it just doesn't interpert the raw values as here is no DB backing the needed information how to do that. If you got the datasheet (if the manufacturer published that at all...Intel for example does) you could convert that raw value showed in CDM to human readable values.
But most important are the differences between "current" (aka "VALUE" in smartctl) and "threshhold". "current" is the current health state and "threshold" is the value that is alarming when "currents" gets below it. Here the "Wear Leveling Count" of 95% and 98% is good, so I would get them if you can't find something better.
Another point to look at is how much TBW the disk is rated for and how much CDM is reporting that it has written. So 11TB written to a 170TB TBW SSD, and 62TB written to a 350 TB TBW SSD.

Postage is a bit annoying but the price for the SSDs itself isn't bad.

Datasheets:
https://www.compuram.de/documents/datasheet/PM863_SAMSUNG.pdf

Oh, I see it, the health status is the value reported in "B1 - Wear Leveling Count", I somewhat overlooked it and thought crystaldiskinfo would be calculating those percentages based on multiple values.

Thank you for clearing up the current/threshold relation, as well as pointing out the Tb written vs TBW specs for the SSD, those tips will help me when looking for SSDs.

 

[zecas]

You can ask the seller to show you the SMART stats before buying. Bought 19 second hand enterprise SSDs from different sellers on ebay and co and always got a picture of the SMART stats so I could verify before buying how much data was written to the SSDs and how much life they got left. None of the 19 SSDs I bought had more than 4% wear. There you can get some great deals like 2x 100GB enterprise SSDs for less than 20$ including shipping. Great deal for a system only striped mirror for PVE.

Have a close look at the warranty. For example Intels warranty for SSDs only includes the initial buyer. If you got them second hand there is no warranty anyway that you could make use of.

Yes, the SM and PM 863 are running great. We have different versions, we use them for almost 10 years now and we neither reached wearout (with running ZFS all the time) nor had a single disk failure. Using them as single mirrors, stripped mirrors and special vdev for huge ZFS pools - all without any problems.

Hi,

Well, I followed your advices and I will replace the EVO SSDs with a pair of PM883 SSD disks. I prefer to be on the safe side, even though budget doesn't always help.

Testing the 2 disks I now have, I found them to be in very good shape. Basically they seem like new drives to me, am I reading the info correctly? They present a very good wear level of 99% and a low total host writes of around 23Gb.

As for the ashift, I believe the best option would be ashift=12, as the drives present the following info on smartctl:

Sector Sizes:     512 bytes logical, 4096 bytes physical

Now at least I'm expecting for better stability and longevity on the SSDs that will receive proxmox OS (PVE) on ZFS raid1. PVE will use a small part of them, so maybe I'll use them to also store some ISO files (I won't need that many ISOs and will not need to update them that often on this build).

Output of smartctl from one SSD bellow.

Thanks

smartctl 7.2 2020-12-30 r5155 [x86_64-linux-5.15.0-25-generic] (local build)
Copyright (C) 2002-20, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Samsung based SSDs
Device Model:     SAMSUNG MZ7LH240HAHQ-00005
Serial Number:    XXXXXXXXXXXXXXXXXX
LU WWN Device Id: 0 000000 000000000
Firmware Version: HXT7904Q
User Capacity:    240,057,409,536 bytes [240 GB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    Solid State Device
Form Factor:      2.5 inches
TRIM Command:     Available, deterministic, zeroed
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ACS-4 T13/BSR INCITS 529 revision 5
SATA Version is:  SATA 3.2, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Tue Jul 19 16:14:30 2022 UTC
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:  (0x00)    Offline data collection activity
                    was never started.
                    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:              (0x53) SMART execute Offline immediate.
                    Auto Offline data collection on/off support.
                    Suspend Offline collection upon new
                    command.
                    No 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:      (  25) 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
  5 Reallocated_Sector_Ct   0x0033   100   100   010    Pre-fail  Always       -       0
  9 Power_On_Hours          0x0032   099   099   000    Old_age   Always       -       1
 12 Power_Cycle_Count       0x0032   099   099   000    Old_age   Always       -       9
177 Wear_Leveling_Count     0x0013   099   099   005    Pre-fail  Always       -       1
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       -       707
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 Uncorrectable_Error_Cnt 0x0032   100   100   000    Old_age   Always       -       0
190 Airflow_Temperature_Cel 0x0032   063   063   000    Old_age   Always       -       37
194 Temperature_Celsius     0x0022   063   060   000    Old_age   Always       -       37 (Min/Max 15/40)
195 ECC_Error_Rate          0x001a   200   200   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0032   100   100   000    Old_age   Always       -       0
199 CRC_Error_Count         0x003e   100   100   000    Old_age   Always       -       0
202 Exception_Mode_Status   0x0033   100   100   010    Pre-fail  Always       -       0
235 POR_Recovery_Count      0x0012   099   099   000    Old_age   Always       -       5
241 Total_LBAs_Written      0x0032   099   099   000    Old_age   Always       -       49236298
242 Total_LBAs_Read         0x0032   099   099   000    Old_age   Always       -       1217387151
243 SATA_Downshift_Ct       0x0032   100   100   000    Old_age   Always       -       0
244 Thermal_Throttle_St     0x0032   100   100   000    Old_age   Always       -       0
245 Timed_Workld_Media_Wear 0x0032   100   100   000    Old_age   Always       -       65535
246 Timed_Workld_RdWr_Ratio 0x0032   100   100   000    Old_age   Always       -       65535
247 Timed_Workld_Timer      0x0032   100   100   000    Old_age   Always       -       65535
251 NAND_Writes             0x0032   100   100   000    Old_age   Always       -       49422976

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%         1         -

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.

 

[Dunuin]

Power_On_hours is one. So its either new or the seller somehow was able to reset the SMART attributes.

 

[zecas]

Power_On_hours is one. So its either new or the seller somehow was able to reset the SMART attributes.

I noticed that low value, and some others like the total gb writes. It's a bit worrying if one is able to change smart data, from that point it means that no one can trust that info when buying disks that are not new...

But then again, other indicators like "Reallocated_Sector_Ct" or "Runtime_Bad_Block" shouldn't be possible to change. Then again, if one can change a parameter, we never know...

What may bring a more reasonable confidence is the fact that this disk label shows a production year of 2021, so maybe the disk can really be basically new, with very little usage.

Given the info from disk label and smart info, and with my knowledge so far, it could well pass like a new disk to me.

 

[alias_fiver]

I've never had a bad enterprise SSD. With every server you buy from a server vendor, you get enterprise grade SSDs. If you want to buy yourself, you can look at this link. Personally I use used PM863 in my home setup, on work I'm using those for over 7 years with a minimal wearout.

This link points to a blog homepage

 

[LnxBil]

This link points to a blog homepage

Yes, so?