QLC versus TLC?

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DougL

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In looking at SSD drives for backups, I'm stunned to see QLC drives being sold (Chinese vendors, mainly) for ridiculously low prices. Maybe a third or a quarter that for TLC drives, which are becoming the industry standard. Now, I understand that QLC can be slow for reading, but for backup disks, who cares? You need to be reading them once in a blue moon. Now, I'm also hearing some skepticism about QLC reliability, which is of major importance for a backup. Aside from the usual reluctance about getting low-cost China-marketed stuff because of quality/performance issues, what are the pros and cons of such disks?
 
arestavo said:
QLC has drastically reduced write endurance vs TLC.

I'd never, ever use one for a C: drive with a page file. If you're not writing a lot to it, and just reading - you'll be fine unless the manufacturer is crap.
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This & this...

And as with alot of things, you only get what you pay for, and I ain't paying a single friggin penny for any cheap-ass, knock-off, spywarez-ridden crap from over yonder :D
 
QLC makes for a good Steam library drive.

For backups it depends. Do you...
- save incremental backups until the drive is full and then start a new drive?
- or do you overwrite the same backup til the end of time?

Obviously QLC is more suitable for the former.

However, SSDs in general are not good for backups on the shelf. Apparently they can forget their contents pretty quickly compared to HDDs when never power up.
 
Once a QLC SSD runs out of pSLC cache, the write speed is slower than even an HDD and the endurance is worse than TLC. Not ideal for prolonged, heavy writes so they're not recommended for write intensive stuff like bulk backups, video editing, external drives, etc.

As a system/OS drive or game install drive which typically involve more reads than writes, they're pretty decent as long as it's from a manufacturer with a reputation of making good QLC and DRAM-less implementations that optimize for these use cases.
 
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As i just posted this in another thread where this drive can be bought for $199..
You are paying for bottom of the bin performance.

The Crucial P3 Plus found itself at the bottom of the leaderboard in virtually all of our tests (the exception was sequential writes, where it was first place with 4.1GB/s). But to be fair, even categorizing the drive is tough. Without Crucial disclosing the NAND used, we initially started testing this drive as a standard TLC drive, which yielded devastating results. Once we dug into the components to find it uses QLC NAND, we ran our lighter SSD testing protocol, which was still pretty poor.

As for the rest of the results, it recorded peak performance of 164K IOPS in 4K reads, 65K IOPS in 4K writes, 27K IOPS (or just 1.7GB/s) in 64K sequential reads, all of which were significantly behind the other tested QLC drives. VDI benchmarking results told a similar story, placing well back of the leaders in boot, initial login, and Monday login tests. It also posted a fairly high average latency of 8ms in our SQL server test.

While these results were certainly disappointing, our biggest rift with the drive was how Crucial markets the P3 Plus. As we indicated above, it is a QLC NAND SSD; however, for some reason, Crucial doesn’t display anything about this on the product page, only that it was called “Micron Advanced 3D NAND.” This is definitely misleading, especially for the average consumer who might not know what they’re about to buy. NAND type is a “crucial” bit of information that consumers need to know, as it plays a big factor in how the SSD will perform.
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https://www.storagereview.com/review/crucial-p3-plus-ssd-review
 
Ha ha. Temu is advertising these for $15-20 (500GB-1TB) Again, for backups, speed is NOT an issue. For this application "performance" isn't speed. It's about reliability. But yes, a cheap-ass, knock-off, spywarez-ridden crap from over yonder probably isn't smart, though that's a different issue. This is about overwriting. That's interesting that, unpowered, SSDs can lose memory. As scheduled backup drives, though, these would never lose power. Never heard that, though. Reference?
 
DougL said:
That's interesting that, unpowered, SSDs can lose memory. As scheduled backup drives, though, these would never lose power. Never heard that, though. Reference?
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Way back some Samsung EVO 840's lost data after not beeing powered on for a while, this was mostly fixed with fiirmware updates, but it's a concern, especially if you are going to let it unpowered for months if not years.
 
I know people who routinely use unpowered USB sticks for long-term storage. You're saying that's not smart? Ten years is supposed to be the standard retention time for non-volatile memory.
 
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You'll swap it out well before it gets worn out. Storage is getting cheaper and cheaper each day. It's about £35 for 1TB SSD now.
 
I'd only consider QLC if it cost much less than a TLC drive. With TLC drive prices having come down considerably this year QLC seems pointless.
 
If it's just for backup, I can't imagine why anyone would use an SSD. Buy hard drives. At least they have a better reputation of clinging to the bits when powered off, unlike marginal QLC SSD's.
 
I got a cheap Crucial 4TB QLC drive and while it fits my current use case (storing blu-ray rips in a practically fanless home server in my living room) I can confirm that write speed is abysmal. Like it drops down to less than HDD speeds then goes back up a bit then down again. It's about 80% full.

So really make sure that it's gonna be used for "WORM" content as the guys over reddit say. ("write once, read many")
 
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