When buying a (consumer-level) hard disk, I normally only pay attention to storage capacity. Is it worth to compare drive speeds also, and if yes, how can this be done?
If performance is your main concern, it's also worth considering whether solid state drives (SSDs) suit your needs. They are (usually) significantly faster than (premium) hard disk drives. But SSDs also cost more per GB, so are often used just for the boot/OS/applications drive; HDDs must still be used for bulk data storage.
So, for me, the relatively minor differences in HDD performance are almost irrelevant because SSDs can fundamentally perform better.
Yes, it's worth it to compare drive speeds if getting your data more quickly holds any advantage for you. For the home user, it's typically a matter of convenience. For a professional server, faster drives mean faster performance under disk I/O load.
Assuming you're looking at drives with the same interface, the most common speed measure, and usually the most significant, is the RPM of the platters. Common values include 4200, 5400, 7200, and 10,000 RPM. High end SCSI drives and the like can go up to 15,000 RPM.
You may see values like seek time, access time, and the like. This will usually be similar for drives of similar rotational speed.
Also, you'll see disk cache sizes, typically a larger cache means it can take better advantage of temporal locality.
Tom's Hardware has some charts of hard drives benchmarks, using h2benchw. Reads are what you spend the bulk of your time doing, but there are write charts there, too.
This tells you how responsive the drive is, how quickly it responds to a sudden small request. I believe this is what best gives the impression of hard drive speed. It's analogous to the "first page out" for printers. Less is better, so the best performer is at the bottom (those boneheads).
This chart will tell you how fast it should make medium to large copies. Using the printer analogy, this would be "pages per minute". More is better, so the best performer is on top.
Storage Review's Performance Database has more benchmarks. They've slowed down the reviewing pace in recent years, but it can give you an idea as to how a family of hard drives is expected to perform. Ignore the IOMeter benchmarks; they only apply to the heavily parallel access patterns found in servers.
Manufacturer supplied stats are a starting point, but you really have to consult benchmarks to have an idea of real world performance. On the Storage Review benchmarks, notice how the 7200 RPM Hitachi beats a 15K RPM drive on the Office Drivemark test. Just citing spindle speeds wouldn't tell the whole story here.
Is it worth to compare drive speeds [sic]
For a system drive where the OS resides, yes. It's one of the slowest data-access components especially considering its high utilization.
For a storage drive/secondary drive, not really. Benchmarks are only useful here to find out if a drive is particularly slow. For this, just look for reliability, good customer feedback, low price and a long warranty period.
Hard disk performance is hard to condense into one number. The primary factors which will affect performance are, in approximate order of importance:
- Spindle rotation rate (for example, 5400, 7200 RPM)
- Platter linear density (number of bits per inch)
- Cache size
Random I/O performance (reads or writes to "random" locations on the disk) is almost completely dependent upon the rotation rate. Sequential I/O performance is dependent upon the product of the rotation rate and the bit density.
You can get 10K/15K RPM drives, but they are smaller (less density!) than 7200 RPM drives. That's great for a database (largely random access I/O), but they are a total waste for storing videos.
Cache size mostly helps with writes (if you enable disk write caching), because the drive can schedule the writes more efficiently, reducing the amount of seek time per write. It doesn't help that much with reads because your OS already does read caching with a lot more memory.
But don't forget to take into account, that faster drives are also more noisy than slower drives due to their highspeed they need bigger (and more noisy) fans and more cooling.
If you have a server in your serverroom noise isn't a real big problem. But with a desktop system and you in front of it it will definitely be.
But i agree on my precommentators. If you are going for a faster harddisk you have to look out for:
- Speed (RPM)
(Not taking into account, that there are high-priced super disks with anti-noising facilities like liquid cooled, gel equipped and something like that)
In general you want a faster drive and more cache.
Faster drives have a lower seek time and higher transfer rate.
Large caches help keep the transfer full.
For example, if you use a site such as Newegg, you can filter on drive speed, capacity, interface, and cache via the advanced search :)
While I pretty much agree with what other posters have said, in a sense, you don't really need to worry.
Although there are clear differences in performance between certain classes of drive (e.g. 5400rpm SATA vs 15000rpm SAS drives), there is not a lot of difference between drives in the same class. If you compared a number of 7200rpm SATA drives of similar ages and capacity, the differences would be minimal and could be countered by other factors such as RAID and partitioning regimes.
Noise, heat, cost and reliability often vary much more and are perhaps more pertinent to most buyers.
Perhaps you could mention what kind of drives you are considering and the purpose you have in mind, in order for us to give more focused advice? I'm assuming that you are a consumer and are pondering choices of SATA drives?
But if you can afford a Solid State Drive, that would be faster than traditional hard disks.