The SSD Anthology: Understanding SSDs and New Drives from OCZ
by Anand Lal Shimpi on March 18, 2009 12:00 AM EST- Posted in
- Storage
Hey, There’s an Elephant in the Room
When the first X25-M reviews went live a few people discovered something very important, something many of us (myself included) missed and should’ve addressed: the drive got slower the more you filled it up. It’s no great mystery why this happened, but it seemed odd at the time because it went against conventional thinking.
LegitReviews was one of the first to spot the SSD slowdown phenomenon, good work Nate.
It’s worth mentioning that hard drives suffer from the same problem; just for a different reason.
Hard drives store data on platters; the platters rotate while an arm with read/write heads on it hovers over the surface of the platter and reads data while the platter spins. The diameter of the platter is greater the further out on the platter you go, that’s just how circles work. The side effect is that for the same amount of rotation, the heads can cover more area on the outside of the platter than on the inside.
The result is that transfer speeds are greater on the outer sectors of the platter than on the inner ones. OSes thus try to write as much data to the outer sectors as possible, but like beachfront property - there’s only a limited amount of space. Eventually you have to write to the slower parts of the drive and thus the more full your drive is, the slower your transfer rates will be for data stored in the innermost sectors.
Fragmentation also hurts hard drive performance. While modern day hard drives have gotten pretty quick at transferring large amounts of data stored sequentially, spread the data out all around the platter and things get real slow, real fast.
Randomness is the enemy of rotational storage.
Solid state drives aren’t supposed to have these issues. Data is stored in flash, so it doesn’t matter where it’s located, you get to it at the same speed. SSDs have +5 armor immunity to random access latency (that’s got to be the single most geeky-sounding thing I’ve ever written, and I use words like latency a lot).
So why is it that when you fill up a SSD like Intel’s X25-M that its performance goes down? Even more worrisome, why is it that when you delete data from the drive that its performance doesn’t go back up?
While SSDs are truly immune to the same problems that plague HDDs, they do also get slower over time. How can both be true? It’s time for another lesson in flash.
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matrixireland - Thursday, December 24, 2009 - link
hi would like to know what you pros think of the;Golden Leopard ASAX-ZIF1.8-SSD? what would you add to it?
And how would you rate it against other ssd?
Specifications:
product description
ASAX-ZIF1.8-SSD is a high-performance design solid state drive based on the high-end micro-control IC with flash memory storage medium integrated advantaged of high speed,convenient ,aseismatic,energy-saving etc.
specification
Model
Size
Interface
Material
ASAX-ZIF1.8-SSD
1.8inch 70×54×6mm
ZIF
Aluminum-magnesium alloy appearance ,drawbench and colorful oxidation surface,elegant temperament
performance
read speed:80- 96Mbytes/second write speed:50- 60Mbytes/second
support ATA-7 V3 PIO/multi word/ultra DMA MODES
Low power TFBGA,4 channel of flash controller,masked ROM and data SRAM
SAMSUNG flash keeps the data faster on reliability and endurance
Dynamic and static wear-leveling prolong NAND FLASH and SSD for longer life
8/16 bit BCH ECC data error correction ability effectively guarantee the data read security.
Design consideration
Capacity
16G/32G/64G/128G/256G
Average access time
<0.25MS
operating temperature
0-85°
power consumption
DC Input Voltage(3.3V or 5 V ± 10%)Read and write:135mA/194Ma wait:70mA
shock
1500G
Application
the Laptop, pc, server,workstation,portable media player,digital collection apparatus and any computer equipment which need consecutive read and write speed and high reliability storage.
jay401 - Wednesday, March 18, 2009 - link
yeah, he wants "more expensive than" or "too expensive for".Spoelie - Wednesday, March 18, 2009 - link
Second page as well:missing charts before and after this paragraph:
"The chart above shows how much faster these affordable MLC SSDs were than the fastest 3.5” hard drive in sequential transfers. But now look at random write performance:"
Spoelie - Wednesday, March 18, 2009 - link
chart 1 on page 2 now shows sequential read but the paragraph is changed to mention random read ;)page 21: As far as I know, this is THE one of THE only reviews
Some very surprising benchmark results for the ocz vertex, I thought the new firmware tanked sequential read speeds (to 80-90) based on the explanation beforehand, but not according to the actual graphs.
Spoelie - Wednesday, March 18, 2009 - link
third page, first table, first column: SSD and HDD entries are switchedmikaela - Tuesday, March 16, 2010 - link
yeah great info. also great resourceSpoelie - Wednesday, March 18, 2009 - link
page 19: I’d never reviewed it'd & -ed?
HolyFire - Wednesday, March 18, 2009 - link
"I'd never reviewed it" is correct. "I'd" here means "I had", it's Past Perfect tense.FishTankX - Wednesday, March 18, 2009 - link
That should have bolded "too"FishTankX - Wednesday, March 18, 2009 - link
Also, I think the velociraptor vs X-25 figures are swapped. 6 odd ms for the intel drive and 0.11ms for the velociraptor..