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List of SSDs with Power Loss Protection

Yorick

Wizard
Joined
Nov 4, 2018
Messages
1,874
The on-disk/flash format that these drives use has a journaling system much like modern filesystems do, so they know if blocks were not fully written.

I guess that depends on how the flash firmware behaves. If it reports a write as completed only after it has been fully written, then all is well. But if it reports a write as completed while it’s still in the SSDs DRAM cache, and then loses power before completing the write, then I’d assume that can throw ZFS’s assumptions about SLOG write into disarray.
 

HoneyBadger

Mushroom! Mushroom!
Joined
Feb 6, 2014
Messages
4,006
But if it reports a write as completed while it’s still in the SSDs DRAM cache, and then loses power before completing the write, then I’d assume that can throw ZFS’s assumptions about SLOG write into disarray. the device should be put somewhere that doesn't care about data integrity and kept very far away from ZFS
Fixed that for you.
 

TrumanHW

Contributor
Joined
Apr 17, 2018
Messages
172
Hi WaltR. Unfortunately Micron/Crucial's "power loss immunity" is not the same as protection for data in-flight - the implementation on the Crucial MX consumer drives is only guaranteed to protect data at rest from being corrupted by a new write in progress when power is lost. This is not the same as the end-to-end power-loss-protection offered on enterprise drives, which will protect "pending writes" that are in the drive's DRAM cache.

Thankfully the drive does obey the "flush cache" command properly, and will in fact push its DRAM to NAND when asked; but this is limited by the write speed of the NAND and whether or not there are pages free to be "fast programmed" as SLC, so it will likely be slow.

If you do have one, please feel free to benchmark it using the diskinfo command found in the thread in my signature and provide the results. I imagine the SLC write cache could let it deliver some fairly good numbers for bursty workloads, but sustained writes could cause it to choke.

And with all that said - welcome to the forums. :)
That's amazing. I never would have even looked at whether that drive had PLP ...

If this were a sticky ... I'd help the OP consolidate the list so there's an easy way to view it.

(Honestly, I'd like equivalent for Optanes by feature, capacity options, performance, etc ... as Intel PN / product lists suck)
 

saveZFS

Explorer
Joined
Jan 6, 2022
Messages
87
Can anyone say roughly how long the shelf life is before the PLP in an SSD (e.g. Samsung, Intel, Micron) no longer works?
The capacitors are theoretically getting worse from day to day. Is this possibly also displayed by Smart or does it have to be replaced after 5 years at the latest?
 

TrumanHW

Contributor
Joined
Apr 17, 2018
Messages
172
Can anyone say roughly how long the shelf life is before the PLP in an SSD (e.g. Samsung, Intel, Micron) no longer works?
The capacitors are theoretically getting worse from day to day. Is this possibly also displayed by Smart or does it have to be replaced after 5 years at the latest?

That's a really smart question.
 

saveZFS

Explorer
Joined
Jan 6, 2022
Messages
87
Yes, the most important thing would be to know whether the SSDs have a reliable self-test for this and would then display the error in Smart.
 

HoneyBadger

Mushroom! Mushroom!
Joined
Feb 6, 2014
Messages
4,006
It's SMART attribute 175 on Intel DC S3700 SSDs ("Power Loss Protection Failure") from this PDF source:


but I can't speak to others directly. I'll have to check on one of my S3500's when I get a moment.

The document on the Intel site has some details about the NVMe ones


Bit 4: Volatile Memory Backup System has failed (e.g., enhanced power loss capacitor test failure)

I'd think that any decent enterprise SSD will report it somewhere, but where that "somewhere" is might be in question still.
 
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