Help with hard drives
Do people use more than one hard drive to make things run faster using raid ? With hard drives by looking a the spec how do you know what good and bad it it the MHz or speed. I'm new to this and trying to learn. So people talk about ssd to use just for o/s so it starts up faster.
The more you can explain the better.
The more you can explain the better.
First, you can't beat an SSD for fast data access. A mechanical HDD (one with spinning disks and moving head arms) will always be slower than an SSD because of the time it takes to move those mechanical components.
HOWEVER, as you will have noticed, SSD's are MUCH more expensive than HDD's, so the popular practice is to use a modest-sized SSD for the OS and important often-used application software installation, then use a large mechanical HDD for data file storage.
In choosing a mechanical HDD, here are several points to consider:
1. Rotational speed. The faster the disks turn, the faster the data sector being sought can come under the stationary heads. The ones at 5400 rpm are good, and this is commonly used in "green" drives that use less energy (and generate a little less heat) by a combination of slower speed and automatic shut-downs when not in use. The faster ones are 7200 rpm. There are still some super-speed ones around at 10,000 and 15,000 rpm, but they tend not to be available in large sizes,and hence are often very expensive per GB.
2. Buffer size. HDD's always have some RAM on their boards used as a buffer for reading from and writing to the disks. More is better, within limits. Generally, 16 MB is small, 32 MB will perform much better, and 64 MB will be a little better yet. One common combo recently is a 5400 rpm "green" drive with a large 64 MB buffer to improve the performance.
3. SATA vs. IDE. Today IDE is rapidly disappearing - SATA is better and has been on the market and improved for quite a while.
4. SATA I, II, or III. More properly now, these are called SATA 1.5 Gb/s, SATA 3.0 Gb/s, and SATA 6.0 Gb/s. Those numbers are the MAXIMUM data transfer rate for the communication channel from the HDD to the mobo controller. SATA 1.5 Gb/s is the oldest version, and you won't find any for sale. SATA 6.0 Gb/s is the newest standard, designed so that the communications ability will ALWAYS be faster than the data storage device itself, so the communication link is not a limit on performance. In fact, the average data transfer rate achieved by mechanical (rotating disks) HDD's is slower than 3.0 Gb/s, so it really makes no difference for that drive type whether it is rated for 3.0 or 6.0 Gb/s. The same goes for the mobo port it is connected to. HOWEVER, some of the newest SSD's DO exceed 3.0 Gb/s, and should be used on 6.0 Gb/s mobo ports.
5. Test Data. READ reviews of HDD's and SSD's, especially the ones with comparisons of performance specs, on sites like Tom's Hardware. First you'll learn that the performance varies, depending on the type of use. Reads and Writes are a little different. Sequential vs. Random access give very different results. So you need to learn what the tests mean, and assess what you will likely be doing. Then compare the many models' specs. And don't get too hung up on small differences. Ratings of 56 and 59 on some item probably will make NO discernible difference to you in real-world use.
6. Warranty. There may be significant differences in the length of the warranty period. That can be helpful when a problem happens, but many view it more as some indication of the potential reliability of the unit.
7. RAID. There are several different forms of RAID, all VERY different and used for different applications. RAID systems are not well standardized and interchangeable, unlike the HDD units themselves. They are another level of complexity you need to understand before using. For example, RAID0 is popular because many think it offers a big boost in performance speed. I think that advantage today is much less than it was 10 to 20 years ago, so you need to quantify that factor carefully. Moreover, as anyone in this field will tell you, the probability of failure of a RAID0 array is twice that of a non-RAID HDD, and when the failure happens you lose ALL of your disk contents. So RAID0 users, MORE than others maybe, need to maintain good backups.
8. Backups. REALLY important to guard against failure that destroys data on your HDD. Learn how to do them and verify that the backup data are good, AND how to recover your data after a HDD replacement. Do NOT try to use RAID1 as a backup system - it is NOT protection against many possible disasters.