Crucial BX500 480 GB SSD review

Posted by: Hilbert Hagedoorn on: 09/24/2018 08:07 AM [ 17 comment(s) ]

Crucial announced their new BX500 series SSDs. They did so quite silently at first, the press releases are a little shy and perhaps too shy as Crucial might have created nice value SSD on SATA3 ever. Let's check it out, shall we?

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likeman
Junior Member

Posts: 4

Posted on: 10/16/2018 07:47 PM

However, here we can confirm the SSD is lacking a DRAM buffer, after writing 85% of the 38GB file, the performance drops pretty dramatically towards 85 MB/sec. And here we have uncovered the Achilles heel of TLC when not cached with DRAM.

SSDs don't use the DRAM for cache its used for PAGE Table only (SSDs are not HDDs writes go directly to the NAND), what your seeing here is SSD slow down because it burned the SLC out (witch seem to be 24GB on the BX500 480GB, but i believe its dynamic SLC cache size based on how much data is saved on the SSD, more data saved smaller the SLC cache) and was writing directly to TLC after 24GB

https://www.guru3d.com/articles-pages/crucial-bx500-480-gb-ssd-review,6.html
https://www.guru3d.com/articles-pages/crucial-bx500-480-gb-ssd-review,8.html

it did not show in your other tests are they was taking samples across the SSD space (they dont test all space maxabout 1GB), main thing that will be higher with DRAM less SSDs is Read and Write latencies that can be higher then a HDD at times as more data is on the SSD , the page table has to be managed in the SSD controller itself and read and write the page table from NAND witch is a lot slower then doing it from DRAM

likeman
Junior Member

Posts: 4

Posted on: 10/16/2018 08:03 PM

So you're that one-in-a-million person who doesn't turn on their PC for "six months or more" and complains that the SSD -might- corrupt games which can be downloaded anytime anyway in 5 minutes or less.

as long as you have the up to date firmware on your 840 evo (this fix was passed onto the released 850 and higher products that use TLC) the drive when powered on will perform a idle background scan to find and move the blocks of data in the NAND that are no longer at the correct charge level (so they don't have to use aggressive read retry and ECC to read the data) not seen this issue in other TLC based SSDs but i believe it was more samsung had set the block data move to low a setting and causing aggressive ECC read retry (now it does a block move if charge level is to low or if it had to read the block of data to many times when accessing the data)

https://www.anandtech.com/show/9158/new-samsung-ssd-840-evo-read-performance-fix-coming-later-this-month
5-10 minutes later the drive had automatically restored itself to full speed, this was after a firmware update but in your case of having system off for 6 months a similar thing may happen (but i believe the issue is that the drive is on for 3 months but data has not changed), takes a way longer than 6 months to cause data loss

unfortunately the 840 none EVO never got the update to fix this issue (have press the ADV optimise button manually in samsung magician )

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