I guess it's time for `fsync_but_really_actually_sync_it_please(2)` (and the lower level equivalents in SATA, NVMe etc.)?
Buggy firmware could also screw that up.
I tested four NVMe SSDs from four vendors – half lose FLUSH'd data on power loss (2022)
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Re: I tested four NVMe SSDs from four vendors – half lose FLUSH'd data on power loss (2022)
#12Name the offenders please. I am sure it might be easy to see visually - a lack of substantial capacitor on the board would indicate a high likelihood of data loss.
None of the tested drives use power loss protection capacitors.
Re: I tested four NVMe SSDs from four vendors – half lose FLUSH'd data on power loss (2022)
#13Name the offenders please. I am sure it might be easy to see visually - a lack of substantial capacitor on the board would indicate a high likelihood of data loss.
None of the tested drives use power loss protection capacitors.
We're talking about scenarios where the drives report (untruthfully) that the data has been committed to non-volatile storage _before_ the power is removed
Not scenarios where the data is in the cache when the power drops and the drive is expected to write out the cache with internal power alone.
Re: I tested four NVMe SSDs from four vendors – half lose FLUSH'd data on power loss (2022)
#14Earlier quoted context omitted.
None of the tested drives use power loss protection capacitors.
We're talking about scenarios where the drives report (untruthfully) that the data has been committed to non-volatile storage _before_ the power is removed Not scenarios where the data is in the cache when the power drops and the drive is expected to write out the cache with internal power alone.
Aren't those the same scenario?
Re: I tested four NVMe SSDs from four vendors – half lose FLUSH'd data on power loss (2022)
#15Earlier quoted context omitted.
We're talking about scenarios where the drives report (untruthfully) that the data has been committed to non-volatile storage _before_ the power is removed Not scenarios where the data is in the cache when the power drops and the drive is expected to write out the cache with internal power alone.
Aren't those the same scenario?
No. One is a lie. The other is an attempt at fault tolerance. The later will not claim something that isn’t true, but it will try to do what you want, as a user, as a nice gesture.
Re: I tested four NVMe SSDs from four vendors – half lose FLUSH'd data on power loss (2022)
#16Earlier quoted context omitted.
We're talking about scenarios where the drives report (untruthfully) that the data has been committed to non-volatile storage _before_ the power is removed Not scenarios where the data is in the cache when the power drops and the drive is expected to write out the cache with internal power alone.
Aren't those the same scenario?
The second scenario is what's standard in enterprise class drives used with RAID controllers, the controller reports 'committed' to the OS and _then_ commits the data, it can do this because the path to nonvoltatile storage downstream of the controller has redundant power (the raid controller has a battery backup and the disks have their own battery backups, as well as control logic that guarantees data in the cache makes it to nonvolatile if the power drops out)
The first scenario is for consumer disks, they don't report 'committed' until the data is actually committed. That makes them a whole assload slower. (Unless they lie.)
Looking up the definitions of write-back vs write-thru caching will help you out here
Re: I tested four NVMe SSDs from four vendors – half lose FLUSH'd data on power loss (2022)
#17Twitter yuk, can somebody just post the names of the four tested drives and which passed/failed please?
Re: I tested four NVMe SSDs from four vendors – half lose FLUSH'd data on power loss (2022)
#18That is unfortunate, but I guess those SSDs performed really well and outclassed all others in performance benchmarks? lol
Re: I tested four NVMe SSDs from four vendors – half lose FLUSH'd data on power loss (2022)
#19This is (2022).
Wondering if anything changed since the original tests...
Re: I tested four NVMe SSDs from four vendors – half lose FLUSH'd data on power loss (2022)
#20[flagged]