8mb Cache Raptor's vs. 16mb Seagates

[mcgrunt42]

I have 2 different raid 0's going. My os is on the 74gig 8mb raptor's, I have a storage drive on 2 seagate 16mb cache raid 0, I am getting much higher results on the from hdtach on the seagates, is this right? Also I already have a seagate 500 gig 32 mb cache drive if i got another and put them in a raid 0 would that be even that much faster than the others? And does 64k and 128k striping make that much of a difference , which one is better and what are the advantages and disadvantages of it? Any help is very much appreciated.

[Malpine Walis]

Well, the only answer that I can see from the info that you have provided would be this:

It depends.

What does it depend on? That is the question. And I don't really see enough info to just give you a straight answer. I can tell you a couple of things though.

Generally, the size of the cache on a drive does not say much about the underlying drive. A larger cache makes it somewhat more likely that you will get a cache hit that can come back to your system without the drive having to make a physical move apart from what it is doing sitting otherwise idle.

As far as stripe size goes, that all depends on what data you are pulling off the drive. The fact is that there is no real best stripe size for all data. If you could know for sure that all of your files were generally of similar size, then you could come up with a best estimate for your personal needs. Since files are all different sizes, your performance in level 0 is going to vary somewhat from one file to the next.

Let me consider really silly extremes so that I can discuss matters.

In one case, you make silly large stripes (for grins we will say 10Mb). Now most files will fit nicely inside a single stripe and you lose the advantage of keeping them split across two drives.

In the other case, you make silly small stripes (for grins we will say 1b). Now you should get the most use possible out of both drives as everything is on both no matter what. The problem is that your drives have to spend more time getting the heads to the right parts of the platters to get the data. I would also tend to think that fragmentation would tend to quickly maximize in such a situation.

Of course, nobody would ever try either scheme (I am sure that somebody must have at least once, either experimentally or by mistake but even so...). Remembering that there is no perfect stripe size, you could try experimenting with a few to see what works best for you. However, that is a time consuming PIA. Also as soon as you buy a new game that has a somewhat different file structure, you may well find that what worked well for you before does not work so well for the new game.

What might help would be if you give us some screen caps from the softwware that you are using to test your drives. Someone like tuskenraider who eats this type of info for breakfast may see more info that will help us to help you.

[tuskenraider]

My ear started ringing.......:).

I have 2 different raid 0's going. My os is on the 74gig 8mb raptor's, I have a storage drive on 2 seagate 16mb cache raid 0, I am getting much higher results on the from hdtach on the seagates, is this right? Well in the graph and burst chart, likely. Your Raptors should show 128MB/s average STR(the graph)and 8ms for average reads if they're configured right. Burst speed is a worthless measurement in the software(innaccurate), ignore it. As far as the Seagates, the model matters greatly. The latter higher density plattered .10 and all 11(which I'm guessing you have) series should be averaging 160MB/s or so, with 13.xx averager reads. What does that mean? The Raptors are quicker, the Seagates are faster. For an OS/app drive you typically want quickness, but will welcome more speed. A fast drive would be great if you run apps that deal with large files frequently.Also I already have a seagate 500 gig 32 mb cache drive if i got another and put them in a raid 0 would that be even that much faster than the others? And does 64k and 128k striping make that much of a difference , which one is better and what are the advantages and disadvantages of it? Any help is very much appreciated. Cache doesn't generally determine the real performance of a drive. As mentioned above, more isn't a bad thing, but doesn't guarantee better performance. As far as stripe is concerned, the default 64K stripe is fine for most users. I've tested many stripe sizes over the years and never saw any evidence that one provided an advantage over another for my typical uses(internet, office apps, gaming, music and movie ripping and burning), though the explaination Malpine gives is valid.