I recently updated my quick HowTo for iometer, and added a section on running iometer on a Linux host. It’s actually pretty easy to run iometer disk benchmarks on Linux hosts.
Iometer running on Linux
Run the iometer benchmark on Linux
I recently updated my quick HowTo for iometer, and added a section on running iometer on a Linux host. It’s actually pretty easy to run iometer disk benchmarks on Linux hosts.
Iometer running on Linux
Many thanks for your Advice on running IOmeter on linux. Excellent JOB!
Your comment on SSDs is misleading. Performance isn’t tuned to be high during first use. Performance decreases over time due to the nature of the technology. (an erase-rewrite operation takes longer than a straight write operation).
This is why SSD manufacturers have spent time working on “Garbage Collection” and “TRIM”. These two technologies are designed to keep the drive running at it’s “new” performance levels over it’s lifetime.
To suggest that manufacturers tune performance for initial benchmarks is a bit ridiculous. It’s akin to claiming throughput differences for the start and end of a mechanical drive is also some sort of conspiracy when it’s due to differences in linear vs angular ‘speed’ (https://en.wikipedia.org/wiki/Constant_angular_velocity).
Here are some useful starting places:
https://en.wikipedia.org/wiki/Write_amplification
https://en.wikipedia.org/wiki/TRIM
Well, my comments are based on a presentation from Chris George from DDRdrive, which I attended. He clearly shows that most SSD manufacturers are gaming the benchmarks. See https://www.ddrdrive.com/zil_accelerator.pdf (his discussion on this starts on slide 27 “The untold truth about Flash SSD write IOPS degradation”) or Google for more comments about his findings.
Chris lays everything out pretty simply and just further backs up my point. The differences in advertised vs real world performance is due to the nature of NAND flash. If a sector contains data the whole block needs to be erased and rewritten. The first writes are fast as are any writes to area that have been trimmed or garbage collected.
The sharp drop off you see is directly correlated to the entire drive having been filled with data. Once this happens all writes are the two step erase/write process instead of a simple write.
None of this suggests nefarious intent.
Additionally, real world performance is absolutely dependent on usage scenario. When the drive is being continually thrashed, garbage collection can’t happen. If the system only uses a portion of the drive’s capacity then garbage collection can happen in the background getting you closer to the theoretical numbers.
Obviously Chris is going to paint NAND in the worst possible light as it’s the exact circumstance where DRAM storage is a better choice. He has a product to sell and if he only shows you where NAND is the better choice he wouldn’t be very good at his job, now, would he?
TL;DR. The only thing Chris clearly shows is that NAND as a technology has some shortcomings; not that the performance drop is due to manufacturer’s intent.
Is there any CLI command to stop the running IOmeter execution without using user interface stop button.
Hello,I am running a beta test on a new IBM Flash Memory system and would like to run in a bladecenter environment. All that sounds pretty easy but I would like to run my testing (Dynamo) in Linux. From what I understand the dashboard (IOMeter) needs to run in Windows. whta I have heard is that it is easy to setup but my team is having a hell of a time. Can you describe the way that the system needs to be setup?
Regards,
Alan Campbell