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> as well as trying to overprice SLC out of production. Is it even possible to buy SLC drives any more? For the past 5+ years the only outlet I've been able to

by wahern 4y ago

> as well as trying to overprice SLC out of production. Is it even possible to buy SLC drives any more? For the past 5+ years the only outlet I've been able to find that even advertise SLC is https://www.delkin.com/ https://www.delkin.com/, and you need to speak to sales to even get a price. I just assumed they and any other similar suppliers bought giant lots of chips at the tail end of SLC production and jack up the price on every new order as their supply dwindles. Or maybe they cobble together drives from the tiny SLC chips used for cache on modern SSDs?

userbinator 4y ago
Is it even possible to buy SLC drives any more? Yes, small ones for industrial use. They're extremely expensive, however. Looking at the raw NAND flash prices, SLC seems to still be around $4.60USD/GB, or roughly the same as it was over a decade ago, while MLC is already <$1USD/GB despite only a doubling in capacity. TLC and QLC seems to be down in the $0.10USD/GB. You can still buy raw SLC NAND flash in the smaller capacities of few GBs; this one is only 512MB, at the price mentioned above: https://www.newark.com/micron/mt29f4g08abaeawp-it-e/flash-memory-4gbit-40-to-85deg/dp/80AH7778 https://www.newark.com/micron/mt29f4g08abaeawp-it-e/flash-me... If the pricing was sane, SLC drives would be only 4x more expensive as QLC ones for the same capacity, but that's not what we're seeing today.
- Wowfunhappy 4y ago
  Do you think the pricing difference could be due to economies of scale?
wmf 4y ago
In theory an SSD could run TLC NAND in SLC mode with just a firmware change but I'm not aware of any such drives.
- namibj 4y ago
  Samsung 980 Pro, the original, does that when sufficiently empty, to offer around iirc 10% nominal capacity of SLC-mode write buffer (given they are TLC, that would be around 30% of the NAND).
- wtallis 4y ago
  Enmotus partnered with Phison to produce a QLC SSD that mapped the first several GB of logical blocks to SLC. This was sold bundled with Enmotus's SSD caching software, but it could also be treated as simply having a SLC partition and a QLC partition that are largely independent.
renonce 4y ago
Many TLC drives have SLC cache so if you limit usage of the drive you may effectively use it in SLC-only mode. This does not say anything about its endurance however. If you want endurance, better mirror your data to HDD.
- wtallis 4y ago
  If you want to use a drive as pure SLC, you're probably better off buying a QLC drive than a TLC drive. QLC drives are more reliant on SLC caching and tend to be more reluctant to migrate data from SLC to QLC when it isn't absolutely necessary.
- efreak 4y ago
  Show me software that can mirror an SSD to HDD in realtime without the "backup" being affected by the slower write speeds. I was looking for a way to do this a few years ago, and couldn't find anything. I'd be very happy if I could pull my SSD out, change my boot drive, and boot into my existing OS without any issues. My understanding is that existing solutions for this delay write confirmation until both drives are complete, negating the speed advantage of the SSD.
  - renonce 4y ago
    Check out Syncthing. I personally run two instances of syncthing, synchronization happens very fast and as long as there isn't high write volumes it syncs pretty quickly. If you don't need realtime backup, rsync'ing in a loop would work.

by wahern 4y ago

userbinator 4y ago

Is it even possible to buy SLC drives any more? Yes, small ones for industrial use. They're extremely expensive, however. Looking at the raw NAND flash prices, SLC seems to still be around $4.60USD/GB, or roughly the same as it was over a decade ago, while MLC is already <$1USD/GB despite only a doubling in capacity. TLC and QLC seems to be down in the $0.10USD/GB. You can still buy raw SLC NAND flash in the smaller capacities of few GBs; this one is only 512MB, at the price mentioned above: https://www.newark.com/micron/mt29f4g08abaeawp-it-e/flash-memory-4gbit-40-to-85deg/dp/80AH7778 https://www.newark.com/micron/mt29f4g08abaeawp-it-e/flash-me... If the pricing was sane, SLC drives would be only 4x more expensive as QLC ones for the same capacity, but that's not what we're seeing today.

Wowfunhappy 4y ago
Do you think the pricing difference could be due to economies of scale?

wmf 4y ago

In theory an SSD could run TLC NAND in SLC mode with just a firmware change but I'm not aware of any such drives.

namibj 4y ago
Samsung 980 Pro, the original, does that when sufficiently empty, to offer around iirc 10% nominal capacity of SLC-mode write buffer (given they are TLC, that would be around 30% of the NAND).
wtallis 4y ago
Enmotus partnered with Phison to produce a QLC SSD that mapped the first several GB of logical blocks to SLC. This was sold bundled with Enmotus's SSD caching software, but it could also be treated as simply having a SLC partition and a QLC partition that are largely independent.

renonce 4y ago

Many TLC drives have SLC cache so if you limit usage of the drive you may effectively use it in SLC-only mode. This does not say anything about its endurance however. If you want endurance, better mirror your data to HDD.

wtallis 4y ago
If you want to use a drive as pure SLC, you're probably better off buying a QLC drive than a TLC drive. QLC drives are more reliant on SLC caching and tend to be more reluctant to migrate data from SLC to QLC when it isn't absolutely necessary.
efreak 4y ago
Show me software that can mirror an SSD to HDD in realtime without the "backup" being affected by the slower write speeds. I was looking for a way to do this a few years ago, and couldn't find anything. I'd be very happy if I could pull my SSD out, change my boot drive, and boot into my existing OS without any issues. My understanding is that existing solutions for this delay write confirmation until both drives are complete, negating the speed advantage of the SSD.
- renonce 4y ago
  Check out Syncthing. I personally run two instances of syncthing, synchronization happens very fast and as long as there isn't high write volumes it syncs pretty quickly. If you don't need realtime backup, rsync'ing in a loop would work.