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Making servers faster: SAS vs SATA whats the difference when it comes to hosting?

October 7th, 2008

This article is a very quick rebake of a previous artcle and replaces SCSI for SAS. SAS is an evolution of SCSI and stands for Serial Attached SCSI.

One of the main performance considerations of a hosted server solution or any server system is the disk system, and making the right choice early on can yield dividends down the line. Currently, there are two main choices - SATA and SAS, and we’ll go through both, and talk you through the differences.

The Basics

SATA

-Short for Serial ATA
-Store up to 1.5TB per disk
-Found in most modern PCs & most budget dedicated hosting packages

SAS:

-They are very good for database & email servers and anywhere lots of little (or large) amounts data needs to be accessed simultaneously
-Depending on supplier, they are roughly twice the price per GB to SATA
-Maximum individual disk size is 300GB

The Nitty Gritty

So to start with in terms of performance what is important, is it the data transfer speed or is it the number of simultaneous read/writes or is it the power usage?

What really makes a difference is what you intend to do with your server but there is a good rule of thumb. If you are going to be using a database or your application will be doing lots of transactions such as sending emails, then SAS is the way forwards. If you are serving fairly static pages or files to a relatively small audience then SATA is normally good.

The true difference between SAS & SATA is the number of simultaneous transactions that can take place at one time. The highest number of simultaneous read/writes on a top performing SATA disk is around 200 irrespective of the number of queued transactions. Whereas a SAS disk will be able to go clear of 400 read/writes/s. The transfer speeds for SAS disks are also typically up to around 20% faster than their SATA counterparts.

SAS & SATA Average simultaneous read/writes compared

How do you make it go even faster?

The concept of many hands make light work applies equally to hard drives as it does to most other tasks. By using many disks in arrays rather than just having 2 disks (the majority of people use RAID1 for redundancy) it is possible to create file & disk systems which have very high performance and resiliency. Most are also very scalable, ideal if you are planning on hosting a system which is likely to become extremely busy.

Want more information?

If you need any advice on managed hosting or systems architecture don’t hesitate to give us a call and we will be more than happy to go through whatever projects you are working on with you.

Entry Filed under: Managed Hosting