If i have a Western Digital Velociraptor (for example) with a Data transfer rate (Sequential / sustained transfer rate , i suppose) of 126 MB/s and one SSD that have the same transfer rate of 126 MB/s (is a example ,some ssds will have higher rate, and other smaller) , are both transfer rates comparable ?
I mean , in a hard disk and in a SSD their transfer rates, are valued in the same way , and there isn't any diference no ? ( I know that seeks times and acces times are much better in SSDs) ,
But if you only focus in transfer rate specs , one SSD and one Hard disk with same or very similar transfer rates , could be considered to have similar performance , at least in transfer performance specs,for example when moving large files or doing sequential reading.
Another thing ...
As SSDs Read transfer rates are quite hight (200 - 250 MBs or more ) , probably they are better than a traditional hard disk for sequential readings no ?
But not always are better for write sequential transfer rates,because perhaps a velociraptor or other hdds have higher write rates compared to a lot of SSDs (some SSDs write rates are about 180 MB/s or better,but not all), no ?
There are different ways to measure disk performance, and you have to understand what they are and how they relate to the type of performance you are looking for:
Transfer rate - how quickly a long stream of data can be moved to or from the drive. Important for copying large files or running programs that have to access large files (ie, Photoshop reading RAW picture files, video editing, etc.)
Access Time (also known as "Latency" - how much time it takes from the time an I/O is requested until the data is delivered. Important when you need to read a LOT of files, such as when booting the system, loading applications, or running programs such as a browser which use files for caching.
Hard drives have similar or even better sequential write rates than many SSDs, but SSDs are usually better at sequential read rates. Hard drives in RAID 0 can improve sequential read rates to the point where they're competitive with a single SSD.
But, SSDs blow any and every hard drive, RAID or not, right out of the water when it comes to random I/O performance, and that's the type of performance that makes the biggest difference for most users.
Thanks sminlal. I will see what is better for me .
I want the hard disk for hold the Os , and the basic applications like gimp , and for use in 3D design (Modeling , rendering).
Normally i use 2 distributions of Linux Debian 5.0.3 and CentOS 3.5. Debian for general things , Photography and learn linux , and CentOS i use it for 3D , as the software i use (Called Autodesk Maya) only is avariable to linux distributions that use RPM packages.
I am learning 3d modeling and that is my priority , so i think i will buy a pair of SSDs to put in raid 0 ( I will look for reviews and Benchmarks , and also data sheets from the manufacturer ) to hold at least CentOS, and a pair of Samsung F3 1Tb hard disks or a pair 1TB Black Caviars in raid 0 for storage , for save 3d projects , and like. I will also buy another cheaper HDD for Backups (2 TB if i can).
My actual hard drive , i will use it for the music and other things , and for hold Debian.
One SSD that i have seen and seems interesting is OCZ Vertex Series 30GB 2.5" SATA-II Solid State Hard Drive , that have 230 MB/s read and 135 MB /s write.
A velociraptor alone , its read transfer is about 128 MB/s (at least what i have read in the data sheet) , so a Raid 0 of 2 vertex II SSDs will have higher read transfer rate than two Velociraptor in Raid 0, and probably similar write transfer rate ( I don't know what is the write transfer transfer rate of one velociraptor neither in Raid 0) and much higher access time , so for 130 GBP each 32 GB SSDs i can have a good raid 0.
I will also look for other SSDs , but OZC has a trim script implemented for linux , called wipper , and for example intel no ,i a don't know yet what to do if i need trim and i have bought intel , so i will read a bit and investigate
The maximum transfer rate of a conventional hard drive is measured on the outer(faster) parts of the drive. As the drive gets filled, the transfer rate will degenerate, down to perhaps as much as half.
The SSD will be relatively constant.
The negligible latency of the SSD is most important to the OS drive, where lots of small reads and writes predominate. Raid-0 on a SSD will give you impressive data transfer rates, but that is not much help on an OS drive. I know, I had two 80gb X25-m raid-0 drives. I replaced them with a single 160gb X25-M SSD and my performance seems snappier.
A good strategy would be to use a good SSD for the OS and frequent applications, and a larger conventional drive for storage. An Intel X25-M 80gb drive would be excellent for the OS. If 40gb will suffice, then Kingston has a well priced drive that uses the intel controller.