On Monday, April 08, 2019 09:41:10 AM Alexander V. Makartsev wrote:
> There are NVMe drives and SSDs intended to be used in servers with high
> workloads like cache storage. These server grade drives must be rated
> for at least 3 DWPD (Drive Writes Per Day) or more.
Thanks! I really hadn't encountered the acronym NVMe before.
Looking at some (e.g., by description "SAMSUNG 970 PRO M.2 2280 512GB PCIe Gen3. X4, NVMe 1.3 64L V-NAND 2-bit MLC Internal Solid State Drive (SSD) MZ-V7P512BW") seem to be the older style of SSD technology (V-NAND 2-bit MLC) which might be a little more reliable (though more expensive), than
some others which use the 3-D NAND technology, which presumably has about the same longevity / reliability as devices labeled as SSDs which use the 3-D NAND technology -- so I guess I have to be careful in how I shop (which is always the case, anyway).
Two links, both in the same ballpark pricewise:
* [[https://www.newegg.com/Product/Product.aspx?Item=N82E16820147693][SAMSUNG 970 PRO M.2 2280 512GB PCIe Gen3. X4, NVMe 1.3 64L V-NAND 2-bit MLC Internal Solid State Drive (SSD) MZ-V7P512BW]]
* [[https://www.amazon.com/BLACK-SN750-NVMe-Internal-Gaming/dp/B07M64QXMN?tag=pcworld02-20&psc=1&ascsubtag=US-001-2899351-000-1442373-web-20][WD BLACK SN750 1TB NVMe Internal Gaming SSD - Gen3 PCIe, M.2 2280, 3D NAND - WDS100T3X0C]]
And thanks for the explanation / clarification on some of the terminology:
> This means, if you have a 500GB SSD rated for 3 DWPD and it has 5 year
> warranty, then you can safely write 1,5TB to it each day for next 5 years.
> That is 3 * 500 * ( 365 * 5 ) / 1000 = 2737TB in total. (TBW)
> You can convert TBW to DWPD if you want.
> Let's say we have 240GB SSD rated for 768 TBW and it has 5 year warranty.
> That will be ( 768 * 1000 ) / ( 365 * 5 ) = 420GB could be written per
> day, or 420 / 240 = 1,75 DWPD
> Let's say we have 256GB SSD rated for 300TBW and it has 5 year warranty.
> That will be ( 300 * 1000 ) / 1825 = 164GB could be written per day, or
> 164 / 256 = 0,64 DWPD
> IMO, an average consumer grade SSD (preferably MLC NAND based, 240GB+, 5
> year warranty) should be rated at least 1 DWPD to be worth buying, so it
> could be used (without paying constant attention to it,
> implementing various tricks and restrictions to its workload, etc) for a
> very long period of time, extending far beyond its warranty period, if
> your workload is lower than 1 DWPD.
> However, in reality it is so much trouble just to find suitable device.
> This involves browsing through terribly designed manufacturer websites
> with dark marketing patterns  and a pile of specification datasheet
> Also keeping in mind how SSD manufacturers don't like to talk about this
> inconvenient topic for them, trying to hide TBW DWPD ratings by using
> MTBF ratings instead.
>  https://darkpatterns.org/