Seagate Cheetah NS.2 HDs & LSI 3ware SAS 9750-4i RAID Card

Seagate Cheetah NS.2 - Introduction

Seagate is well known for their popular Barracuda line-up of SATA hard drives that provide optimal performance for pretty much any task you are looking for. However, if you are into hard drive intensive tasks like high-definition video editing and compositing, standard SATA hard drives could be a big bottleneck in your system. I personally work with lots of high-definition 1080p uncompressed video footage, and my two Western Digital RAID Edition 1TB hard drives in a RAID 0 configuration were not able to handle uncompressed HD footage without any lags. You might wonder, well what type of performance does an uncompressed HD footage require from a hard drive? Well, to answer that, it really depends on file formats and the amount of complexity of the scene, but usually, it is in between 100-300MB/s transfer/read speed. Since two standard 7200RPM 3.0Gb/s SATA II hard drives can only handle around 115-200MB/s in average, a person could easily see performance decreases in their production, especially when combining more than one uncompressed footage in their composition.

This is why Seagate also comes with high-performance SAS (Serial Attached SCSI) server based hard drives, like the Seagate Cheetah NS.2. We are reviewing four Seagate Cheetah NS.2 600GB 10,000RPM 6.0Gbit/s SAS hard drives in order to see how well they perform in tasks like video editing and composing. We are going to explain everything in the results section on how many hard drives and what type of configurations will work well with uncompressed high-definition videos, but before we do that, let's go a bit more into detail about the Seagate Cheetah NS.2 hard drives so we could understand what makes these hard drives so special.

The first thing that you will find very interesting is that this hard drive uses the new 6.0Gb/s interface design, which allows for double the throughput speed then what was possible previously on the older 3.0Gb/s interface. Many new motherboards are coming out with SATA slots that already use the 6.0Gb/s interface, but the difference is that these hard drives are Serial attached SCSI based and not SATA, so you would not be able to attach these drives to just the motherboard, unless the motherboard comes with a SAS controller specifically. Another interesting fact is that even though these new motherboards are already out with the new 6.0Gb/s interface, most motherboards are only able to achieve this speed by limiting the system to only non-SLI or non-Crossfire based systems, meaning, you cannot use more then one video card. It will not only limit the user on the video cards, but it will also lower the PCI-E slot speeds to 8x, which means that there will be less performance from the video card. Now just like I have mentioned before, the Seagate Cheetah NS.2 hard drives are SAS drives, so in order to get these bad boys running, we need a special RAID controller card, that is capable of Serial attached SCSI's and the new 6.0Gb/s interface. 3.0Gb/s RAID cards will work, but the performance will be lowered. In this case, we will be using LSI's 3ware SAS 9750-4i RAID controller card to accomplish the most out of our video editing. Since these RAID cards work separately from the motherboard, except they use the PCI-E slots, they do not have any limitations like current motherboards do. As a matter a fact, they have a very important role with SAS drives, which we will go into more detail about on the next page.

The second interesting part of this hard drive is that it runs at 10,000RPM.This not only allows for lower access times, but also for faster transfer and read speeds. The combination of the new 6.0Gb/s interface and the 10,000RPM capability allows for better performance then what we have already seen.

And finally, the main big difference between SAS drives and SATA drives is the way they access the information. SATA drives access information mainly under Sequential Access Pattern, while SAS drives access information through Random Access Patterns. If writes are sequential on a disk, it minimizes seek times on the hard drive, and the data can be written much faster, while random access results in many seeks across the hard drive that can slow down the process dramatically. This brings up another question, why would SAS drives be Random Access Pattern based if they could be Sequential Access Pattern based for more performance on tasks like video editing? Well, the answer lies behind the reason for building SAS drives. SAS drives were mainly built for "transactional applications that require constant and immediate access to data. These applications, ranging from highly critical databases to email servers, rely on exceptional performance, reliability, and availability. Online storage is powered on 24x 7, handles mostly random  requests, and has high IOPS and high duty cycles" (LSI) So while its main purpose is not video editing and compositing, its exceptional performance with the help of a hardware based RAID card can drastically improve performance even though the drives are set to Random Access Patterns.

Why Not SSDs?

Well there are not many reasons why one could not use SSDs instead of hard drives. As a matter a fact, SSDs would probably be a better option when combined with a powerful RAID card, but one of the main reasons why SSDs are inconvenient are because they are extremely expensive and do not provide much capacity. We get a total of 2400GBs of hard drive space if we use the RAID0 configuration with our SAS drives, and the overall cost with the RAID card comes out to be around 3000 dollars. If we would want to get as much capacity from SSDs, the overall price would be around 8000-10000 dollars. That is about 3x more then what a SAS setup would cost. This is why a SAS setup is a better choice for film makers and people on the budget.