How do we test?

Testenvironment

We recommend that readers who aren't interested in test procedures jump over this page and head directly to the test results.

Models	Capacity	NAND Flash
OCZ Vertex 3 240 GByte MLC	240 Gigabyte	synchronous
Kingston HyperX 240 GByte SSD	240 Gigabyte	synchronous
OCZ Agility 3 240 GByte MLC	240 Gigabyte	asynchronous
ADATA S511 120 GByte SSD	120 Gigabyte	synchronous
Corsair ForceGT 120 GByte	120 Gigabyte	synchronous
Kingston HyperX SSD 120 GByte	120 Gigabyte	synchronous
Corsair ForceGT 120 GByte	120 Gigabyte	synchronous
ADATA S511 60 GByte MLC	60 Gigabyte	synchronous
Testenvironment
Motherboard	ASUS P8P67 Deluxe
Chipset	Intel P67	1'333 MHz
CPU	Intel Core i7 2600k	3.4 GHz
Memory	Kingston HyperX 2133	4 GByte
Graphics card	Gigabyte GeForce GTX 285
Storage (system)	Seagate Barracuda	640 GByte
Operating systems	Ubuntu 10.04
Filesystem	XFS

We think everybody reading this article can imagine the following scenario: You just bought a hard drive which according the specs sheet should transfer 120 MByte/s reading and writing. In the reviews you read about astonishing 110 MByte/s but after you put the drive into you system it feels much slower. The whole story gets even worse when you start a benchmark which does randomread/write of 4 KByte blocks. There you only get two to three MBytes/s.

Because of this we don't want to publish screenshots of standard programs like HD-Tach, HD-Tune, ... we want our tests to be

• reproducible,
• accurate
• meaningful and
• varied ...

... sind.

We test with activated caches and NCQ (Native Command Queueing) because they're also activated under daily use. But the data size tested is always at least twice the amount of the memory. In this there will be no intereference.

We noticed that the measuring error is constantly within ±2%. Therefore we mention it only here.

Additionally we evaluate the S.M.A.R.T. data to assess if there are already errors.

The following table give you a brief overview to which points we turn our centre of attention.

Test	Observations
Sequential Read/Write Tests	Are the values within the specifications? Which influence has the block size? Which influence has the filesystems block size?
Random Read/Write Tests	How severe is the influence on the theoretically possible (sequential) datarate? Which influence has the block size? Which influence has the block size on the filesystem?

iozone3

iozone3 is a benchmark suit for storage solutions which natively runs under Linux.

Therefore we are testing the throughput with different block sizes using the following commands:

KByte/s

• iozone -Rb test4k.xls -i0 -i1 -i2 -+n -r 4k -s4g -t32
• iozone -Rb test16k.xls -i0 -i1 -i2 -+n -r 16k -s4g -t32
• iozone -Rb test32k.xls -i0 -i1 -i2 -+n -r 32k -s4g -t32
• iozone -Rb test64k.xls -i0 -i1 -i2 -+n -r 64k -s4g -t32
• iozone -Rb test128k.xls -i0 -i1 -i2 -+n -r 128k -s4g -t32
• iozone -Rb test256k.xls -i0 -i1 -i2 -+n -r 256k -s4g -t32

iops

• iozone -Rb test4ko.xls -i0 -i1 -i2 -+n -r 4k -s4g -t32 -O
• iozone -Rb test16ko.xls -i0 -i1 -i2 -+n -r 16k -s4g -t32 -O
• iozone -Rb test64ko.xls -i0 -i1 -i2 -+n -r 64k -s4g -t32 -O
• iozone -Rb test96ko.xls -i0 -i1 -i2 -+n -r 96k -s4g -t32 -O
• iozone -Rb test128ko.xls -i0 -i1 -i2 -+n -r 128k -s4g -t32 -O

 

Why do we test different block sizes?

It is important to reproduce scenarios of daily usage. Certain parameters need to be variable during the test to make a statement about the product. In our test the parameters are the different block sizes. It defines the size in KBytes which is written/read on the drive during a transaction.

With this method one can test the reading and writing of either small and big files. In a normal personal computer environment you usually don't find many files smaller than 4 KByte. The relative amount of small files is much bigger on a mail or database server. Therefore tests with small block sizes are of interest for database-based applications.

In bigger RAID arrays the hard disk cache is usually disabled and the RAID-Controller takes over the job of caching. Exactly in such setups hard drives need to be very fast when reading or writing small amounts of data. Sequential throughput isn't interesting in this case.

Page 1 - Introduction / Specs / Delivery	Page 7 - Random read KByte/s
Page 2 - Impressions	Page 8 - Sequential write ops
Page 3 - How do we test?	Page 9 - Sequential read ops
Page 4 - Sequential write KByte/s	Page 10 - Random write ops
Page 5 - Sequential read KByte/s	Page 11 - Random read ops
Page 6 - Random write KByte/s	Page 12 - Conclusion

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