Samsung SSD 845DC EVO/PRO Performance Preview & Exploring IOPS Consistency
by Kristian Vättö on September 3, 2014 8:00 AM ESTSamsung PM853T
| Samsung PM853T | |||||
| Capacity | 240GB | 480GB | 960GB | ||
| Controller | Samsung MEX | ||||
| NAND | Samsung 19nm 128Gbit TLC | ||||
| Sequential Read | Up to 530MB/s | ||||
| Sequential Write | Up to 410MB/s | ||||
| 4KB Random Read | Up to 87K IOPS | ||||
| 4KB Random Write | Up to 15K IOPS | ||||
| Endurance (DWPD) | 0.3 DWPD (4KB Random) / 1.6 DWPD (64KB Sequential) | ||||
| Warranty | Three years | ||||
The PM853T is the OEM version of the 845DC EVO and as you would expect, the two are very much alike. The difference between the 845DC EVO and PM853T is the firmware and the PM853T is geared more towards sustained workloads, which results in slightly higher random write speed (15K IOPS vs 14K IOPS) for the highest capacity. Endurance is also a bit lower (0.3 DWPD vs 0.35 DWPD) and warranty has dropped from five to three years, but otherwise the 845DC EVO and PM853T should be alike. Unfortunately I do not have the full data sheet, so all the specs are 'up to', but I will update the table when I receive the full specs.
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Inds - Wednesday, February 4, 2015 - link
Ok, this doesn't clear anything up. If my manufacturer is lying about the IOPS of my SSD, how do I figure out the real value?If they aren't lying about the 97,000 random read IOPS, how many megabytes per second is this for 4KB?
What exactly is the formula? You never elaborate on this in the article beyond senseless ramble.
First of all, how am I gonna know what the queue length even is? The way I see it on benchmark tests, low queue depths have lower MB/s than higher ones so this confuses the hell out of me.
But okay, I wanna know how my 840 Evo will perform random reads in the worst case scenario and QD1 seems to be the worst case scenario according to all the benchmark evidence.
In that case, I must time the QD by the latency. My latency I believe is 1 ms so my result is 1000. 1000 IOPS? Okay, so my 4KB random read speed will be 4 MB/s? That's nowhere close to the real result CrystalDiskMark shows.