Beyond being a druid, I am a Storage Architect with experience with arrays from HDS, NetApp, Compaq/HP, and EMC. This will be my space to talk a little about the things I see and the effect they will have on the industry.
Solid State versus Fiber Channel: Where's the performance?
Posted 06/09/09 at 9:02 PM by Zeln
Recently one of the performance folks at the site I work out came to me with a question. He was putting together some numbers for disk performance and had come up with an interesting issue.
The intergalactic standard formula for average disk access is:
Average seek time + Rotational Delay + Transfer Rate of Data + Controller Overhead
Looking at EMC’s specification sheet for the new V-Max, we get the following values for
450GB Fiber Channel drives
Average seek time: 3.4/3.9ms
Rotational Speed: 15,0000RPM
Internal Data Rate: 1051-2225 Mb/s
400GB Enterrpise Flash (SSD)
Average Seek: 0
Rotational Speed: 0
Internal Data Rate: 800-1600 Mb/s
Considering Rotational Delay is inversely proportional to Rotational speed, we are faced with the only factors SSD is faster than Fiber Channel are very small numbers. In fact, plugging the averages for seek time and data rate into the formula and your average disk access time for 450GB Fiber Channel drives is 1.31 seconds while SSD is 1.41 seconds.
Considering that Enterprise Flash (SSD) from EMC is 8 times more expensive than its Fiber Channel, why would you buy it over the Fiber Channel?
It’s all about the IOPS
Input/Output Operations per Second is a measurement of disk performance. Basically, it measures how a system can handle heavy operations. The more IOPS at a lower response time the better a system can handle heavy read or write operations. SSD drives can sustain 5000 IOPS while maintaining 1ms response time, while the 450GB drives can sustain 120 to 180 IOPS with a 5ms response time.
So here’s the skinny. If you can’t keep your SSD busy then you’re wasting your money. But in situations where you have heavy read/write I/O, then the SSD will easily handle it where your Fiber Channel will choke.
By the way, if you ever want to take a look at the drives that every single well known storage manufacturer uses (EMC, HDS, HP, IBM, etc…) go to STEC | A Global Technology Leader of Award-Winning, Precision Engineered OEM SSD and Memory solutions and take a look at the Zeus drives
The intergalactic standard formula for average disk access is:
Average seek time + Rotational Delay + Transfer Rate of Data + Controller Overhead
Looking at EMC’s specification sheet for the new V-Max, we get the following values for
450GB Fiber Channel drives
Average seek time: 3.4/3.9ms
Rotational Speed: 15,0000RPM
Internal Data Rate: 1051-2225 Mb/s
400GB Enterrpise Flash (SSD)
Average Seek: 0
Rotational Speed: 0
Internal Data Rate: 800-1600 Mb/s
Considering Rotational Delay is inversely proportional to Rotational speed, we are faced with the only factors SSD is faster than Fiber Channel are very small numbers. In fact, plugging the averages for seek time and data rate into the formula and your average disk access time for 450GB Fiber Channel drives is 1.31 seconds while SSD is 1.41 seconds.
Considering that Enterprise Flash (SSD) from EMC is 8 times more expensive than its Fiber Channel, why would you buy it over the Fiber Channel?
It’s all about the IOPS
Input/Output Operations per Second is a measurement of disk performance. Basically, it measures how a system can handle heavy operations. The more IOPS at a lower response time the better a system can handle heavy read or write operations. SSD drives can sustain 5000 IOPS while maintaining 1ms response time, while the 450GB drives can sustain 120 to 180 IOPS with a 5ms response time.
So here’s the skinny. If you can’t keep your SSD busy then you’re wasting your money. But in situations where you have heavy read/write I/O, then the SSD will easily handle it where your Fiber Channel will choke.
By the way, if you ever want to take a look at the drives that every single well known storage manufacturer uses (EMC, HDS, HP, IBM, etc…) go to STEC | A Global Technology Leader of Award-Winning, Precision Engineered OEM SSD and Memory solutions and take a look at the Zeus drives
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