Effective Read/Write speeds

[xConVirus]

Hey guys, I've got some questions about effective performance of hard drives and solid state drives. It's advertised all the time how much faster SSDs are than HDDs in terms of Read/Write speed and IOPS, but I was wondering if someone might be able to explain or link me some articles that explain sufficiently well the relation between these numbers and actual daily use performance.

 

For example, I have an M.2 SM951 128GB drive from Samsung advertised for ~1900MB/s Read and ~600MB/s Write speeds but I don't recall ever seeing actual performance over about 60MB/s Read/Write speed monitoring through the performance manager in Windows (not the most reliable monitor I guess). When I use the performance benchmark utility Samsung provided, it's telling me I'm getting about ~1800MB/s and ~530MB/s Read/Write. But I'm assuming this means Sequential and not random. So my question is, how do you find out the average performance in daily use situations with these drives? Does higher sequential read/write always been higher random performance? Or does higher IOPS mean higher random performance? Thanks guys.

[mikat]

Hey guys, I've got some questions about effective performance of hard drives and solid state drives. It's advertised all the time how much faster SSDs are than HDDs in terms of Read/Write speed and IOPS, but I was wondering if someone might be able to explain or link me some articles that explain sufficiently well the relation between these numbers and actual daily use performance.

 

For example, I have an M.2 SM951 128GB drive from Samsung advertised for ~1900MB/s Read and ~600MB/s Write speeds but I don't recall ever seeing actual performance over about 60MB/s Read/Write speed monitoring through the performance manager in Windows (not the most reliable monitor I guess). When I use the performance benchmark utility Samsung provided, it's telling me I'm getting about ~1800MB/s and ~530MB/s Read/Write. But I'm assuming this means Sequential and not random. So my question is, how do you find out the average performance in daily use situations with these drives? Does higher sequential read/write always been higher random performance? Or does higher IOPS mean higher random performance? Thanks guys.

http://crystalmark.info/software/CrystalDiskMark/index-e.html

this is your friend

[BaileyFY]

I'm no SSD know it all but you'll be very unlikely to replicate the very max of an SSD's quoted performance due to bottlenecking in one form or another.

Heres a couple of resources that go in to a fair bit of depth

 

http://www.thessdreview.com/featured/ssd-throughput-latency-iopsexplained/

 

http://www.gamersnexus.net/guides/785-ssd-dictionary-understanding-ssd-specs

 

My MBP's ssd is quoted for 2000MBs read and 1100MBs write but in benchmarks I usually get  1870MBs read and 1050MBs write.

[juretrn]

snip

First of all, Samsung's numbers are a bit bull; they use caching in RAM to achieve them. It's a feature you will get to use even in real world applications, but it's still bull, as cache is by definition relatively small. Main benefit of SSDs is not write/read speed, but rather access times- several orders of magnitude smaller compared to HDDs. This is where the main performance difference comes from. 

Modern drives are limited by SATA 3 interface to theoretical maximum of about 600 MB/s.

[xConVirus]

http://crystalmark.info/software/CrystalDiskMark/index-e.html

this is your friend

 

I'm no SSD know it all but you'll be very unlikely to replicate the very max of an SSD's quoted performance due to bottlenecking in one form or another.

Heres a couple of resources that go in to a fair bit of depth

 

http://www.thessdreview.com/featured/ssd-throughput-latency-iopsexplained/

 

http://www.gamersnexus.net/guides/785-ssd-dictionary-understanding-ssd-specs

 

My MBP's ssd is quoted for 2000MBs read and 1100MBs write but in benchmarks I usually get  1870MBs read and 1050MBs write.

 

First of all, Samsung's numbers are a bit bull; they use caching in RAM to achieve them. It's a feature you will get to use even in real world applications, but it's still bull, as cache is by definition relatively small. Main benefit of SSDs is not write/read speed, but rather access times- several orders of magnitude smaller compared to HDDs. This is where the main performance difference comes from. 

Modern drives are limited by SATA 3 interface to theoretical maximum of about 600 MB/s.

 

Wow you three hit each part really well. @mikat Thanks for the utility, I think I've heard of that before. I'll definitely try it out later tonight.

 

@BaileyFY Great links, makes a lot more sense now. I didn't think it was as simple as just looking at higher Read/Write speeds.

 

@juretrn Your short summary helped me make sense of the links ^ provided, thank you. Would you mind linking me an article about the caching you're talking about?

[juretrn]

Wow you three hit each part really well. @mikat Thanks for the utility, I think I've heard of that before. I'll definitely try it out later tonight.

 

@BaileyFY Great links, makes a lot more sense now. I didn't think it was as simple as just looking at higher Read/Write speeds.

 

@juretrn Your short summary helped me make sense of the links ^ provided, thank you. Would you mind linking me an article about the caching you're talking about?

http://www.anandtech.com/show/7173/samsung-ssd-840-evo-review-120gb-250gb-500gb-750gb-1tb-models-tested/5