Performance in FC-Test
For this test two 32GB partitions are created on the virtual disk of the RAID array and formatted in NTFS and then in FAT32. After that a file-set is created of the hard disk. It is then read from the disk, copied within the same partition and then copied into another partition. The time taken to perform these operations is measured and the speed of the array is calculated. The Windows and Programs file-sets consist of a large number of small files whereas the other three patterns (ISO, MP3, and Install) include a few large files each.
We’d like to note that the copying test is indicative of the drive’s behavior under complex load. In fact, the HDD is working with two threads (one for reading and one for writing) when copying files.
This test produces too much data, so we will only discuss the results of the Install, ISO and Programs patterns in NTFS which illustrate the most characteristic use of the arrays. You can use the links below to view the other results:
SAS drives are always slow in the writing test on the LSI controller and we have already got used to that, but the results of the Promise controller without a BBU are downright disappointing. The RAID5 and RAID6 arrays are very slow. However, there is one interesting thing about their results: they show maximum speed not in the ISO pattern which has the largest files but in the Install pattern. It means that these arrays depend on the size of the files, and the dependence is not directly proportional.
Note also that the eight-disk RAID10 is always behind the four-disk RAID0 just as in the sequential read test. The difference is small, yet noticeable.
Like in the multithreaded test, there are low speeds at a small queue depth. As a result, most of the arrays deliver the same speed on large files, the four-disk RAID5 making the only difference.
The speeds decline when the file size is reduced, especially with the eight-disk arrays that are slower than the single drive. The four-disk RAID10 is surprisingly the fastest array of all, which is very odd.
Copying within the same partition is almost predictable but there are still problems with writing to the RAID5 and RAID6 arrays due to the disabled cache of the controller. The four-disk RAID10 is rather too slow and loses to the single drive – it has problems with writing, too.
It’s the same when copying from one partition to another but the speeds are lower and the eight-disk RAID10 is too bad with large files. Well, the results of the RAID0 arrays are not really good as they provide but a small advantage over the single drive. And that’s all because the controller works without a BBU.