Single Disk vs Raid 0 (128k)

We’ll start with the most obvious one, RAID 0 vs Single Disk performance. In the charts below we compared a single Vertex to two of them in Raid 0 (stripe size 128k).

The data is presented by a percentage increase/decrease over the single disk setup.

AS SSD Benchmark

First up is a pretty new benchmark called AS SSD Benchmark. A raw translation of the German details below:

The synthetic tests to determine the sequential and random read and write performance of the SSD. These tests are carried out without the use of the operating system caches. In the program Seq-test measures how long it takes to read a 1 GB large file, respectively, to write. In the 4K test will determine the read and write performance for random 4K blocks. The 4K-64-THRD-test corresponds to the 4K procedure except that the read and write operations are spread across 64 threads (typical start of a program).

In all three synthetic test is the test file size of 1GB. Last, still determines the access time of the SSD, the access of which is determined to read through the entire capacity of the SSD (Full Stroke). Write access test only to be met with a 1 GB big test file.

First up are READ speeds:



Sequential and threaded 4k read operations see a ~100% speed increase, the ideal result when going from one to two disks setup. The single threaded random 4k drops about ~20% though. Read Access times go slightly up, but negligible.



Write performance is up all over the chart, the biggest gain is random 4k: 136% faster! Write access is also better with the drives in RAID.

Next up the “normal” copy/paste tests, which don’t bypass the OS cache;

In the copy test (menu Tool-copy benchmark) the following test folders are created: (ISO) two large files, programs) (typical program folder with many small files) and games (folder of a game with small and large files. These three folders are copied with a simple copy command of the operating system. The cache is turned on for this test.

The smaller the files, the bigger the performance increase, RAID + OS cache really pays off here, almost 3x faster than single disk!

HD Tune

The synthetic benchmark HD Tune is more widely known.



Sequential read tests are quite promising, at its worst there’s a 153% performance boost; average read is 2x better than single disk.



The write performance boost is less pronounced in this test, hovering at ~60% average.

The Random Access tests display average throughput using different size file chunks:



The random read with 1024Kb goes up, but with smaller file chunks performance is down ~20%.



Random write is “better”, meaning there’s less loss of performance this time with smaller file chunks.

FC Test

FC Test, or File-Copy Test is a small straight forward application. You can measure the time it takes to create files of different size, then measure how long it takes to copy them between volumes, and also measure how long it takes to delete them. For our test we were interested in the write/creation speeds. So we used the PROG,WIN,MP3 and ISO templates to measure the disk speed.



Going from single SSD to two in RAID 0 will give you a noticeable boost in real world applications, large sequential ISO does the best. Which is interesting as the AS SSD benchmark had the ISO test as one of the “lesser” ones. Overall we get at least 70% boost up to 100%

PassMark

The last benchmark used in this article is PassMark, a system benchmark tool which sports a quite complete HDD performance test. Allowing you to define different “worker” threads that can replicate “real world” drive usage. We used PassMark patterns: Database, FileServer and Workstation, we also created a custom random write thread.

Database: 10% Sequential / 90% Random IO, 90% Read / 10% Write, 2k file chunks, Asynchronous 128 queue

FileServer: 0% Sequential / 100% Random IO, 80% Read / 20% Write, 16Kb file chunks, Asynchronous 128 queue

Workstation: 20% Sequential / 80% Random IO, 70% Read / 30% Write, 16Kb file chunks, Synchronous

Custom: 0% Sequential / 100% Random IO, 0% Read / 100% Write, 4k file chunks, Synchronous



These tests put your storage through some serious workloads, few people will match this with day to day usage, surfing, email etc. That said, 4k write performance with RAID gets a spectacular boost, the same as seen in the AS SSD benchmark. The FileServer and Database patterns get a nice boost too, only the Workstation setup, which has a higher write/read balance than the other two default patterns, gets a very small boost.

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Overall we can conclude that you can expect a 50~200% boost in disk performance going from single SSD to two of them in RAID 0. Sequential operations will benefit the most, but smaller file operations won’t be slower than a single disk, on average.