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Looking for the best performance option (HDD).

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September 28, 2007 5:31:29 PM

I've got 100$ to spent on something funny for my comp, and since I've never tried running RAID before I figured I would try it out.

I've been looking around a bit to see what I can get and came down to two options.

1) Two times Hitachi DeskStar 7K160 160 GB HDD / 7200 rpm / 8 MB / 8.5 ms / 300 MBps
or
2) Mylex DAC960 RAID Controller and 2 x 18,2 GB IBM SCSI HDD's 10.000 rpm / 68P Ultra 3 / 4MB cache / 5.2 ms (Model DDYS-T18350)

I've never run SCSI before and the more I try to read about how this stuff works the more confused I seem to get. It seems like there is quite a few things to take into consideration, I mean, what good would it do to have some fast HDD's if the controller sucks and can't keep up? The thing is, I can't seem to find any specific/reliable info on this controller.

The first option would cost me around 110$ or so and the second one is from an online auctions which I anticipate will cost me around 50 - 65$. Since I'm interested in the best performance for the money I guess I should go with the SCSI drives.

Really, the reason for my post here is to make sure I'm not doing something stupid if there is a better solution.
Whats your opinion on this?

EDIT: Here is a picture of the SCSI controller along with one of the HDD's.
I'm a bit concerned about there only being one 68pin connector on the controller, won't that cost me some speed if I run RAID on two drives connected on the same cable?


Enlighten me plz.

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September 28, 2007 11:08:14 PM

If I were you I'd just stick with ATA drives. SCSI is a lot more involved and is unlikely to be faster, as SCSI drives have firmware designed for server usage, not desktop usage.

Don't worry about the single connector - SCSI is a parallel standard and as such runs down one cable. Your bottleneck will likely be the PCI bus though - you may hit the 133MB/s bandwidth limit with those 2 hard disks. Also, bear in mind that old non-fluid dynamic bearing SCSI disks are very loud in operation.
September 29, 2007 7:32:10 PM

Unlikely to be faster? _Won't the lower random access time on the SCSI drive make a difference and speed things up significantly? (I must have misunderstood something).
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September 29, 2007 7:46:17 PM

Ok....

Higher rotational speed means a lower seek time.

Higher data density means faster sequential read.


Lets take two scenarios....

A) File Server reading lots of small files (Documents?) all over the disk, or a Database server reading lots of different randomly positioned parts of one large file.

In this case, seek/access time is more important than sequential read. 10k RPM disks will be much faster than 7200RPM disks.

B) Reading one large file from a disk sequentially, like a full frame uncompressed HD video, or writing FRAPs footage, etc.

In this case sustained sequential reads will be more important. This is basically dependant on how fast the head flies over how much data. While a 10kRPM drive is turning faster, the 7.2k drives will have more data in the same area (they have 160GB per platter rather than 18GB). This is why the newer 750GB/1TB drives can read faster than raptors sequentially - the data is much much denser, and the head flys over more GBs in the same time.


Now, without testing both I cant be sure, but I'd hazard a guess that the SATA option would be quicker for sequential reads/writes. Good for pretty HDtach result graphs and for large files.

The SCSI drives however will almost certainly be faster for random accesses. Windows will boot faster, BF2142 maps will probably load quicker.

The SCSI implementation you are talking about will however be limited by the PCI bus. You are talking 32bits by 33MHz, or 133MB/s. The card is probably capeable of 66MHz PCI, but your motherboard won't be unless you have bought a server board or a high end workstation board. This is shared between ALL PCI devices. If you have a PCI sound card, a PCI TV card, or anything else like that, it will fight for some of that 133MB/s with the RAID card.

Up to you :) 
September 29, 2007 10:24:06 PM

Thanks for your very informative reply.

For the moment I wouldn't be using any other PCI cards, but that will change once I saved enough money to buy a projector (seriously, TV is outdated) ;P

Anyway, forget the SCSI but let's still talk RAID.
What you are saying is that if I buy the two 160GB disks and run RAID on them I would get a lot faster read/write with large files, but will that shorten load time? I mean will my PC boot faster than it does now without RAID and how much faster? 50%? where it would be 80% with the SCSI drives?

Sry. for asking so much but the thing is, if running RAID on the two 160GB drives won't make much difference anyway I might as well buy a 500GB disk and get full value for my $. (phew, what am I gonna do with all that space)

Of course I could let the whole thing go and buy some more RAM instead.. hmm..


September 29, 2007 11:07:08 PM

I vote for buying more ram. It depends what you want the HD for but if it's just general system performance more ram is better. I'm running 4gigs under 32bit xp. The system can only use 3.4 gigs but it seems better than 2.

If you raid 2 drives for speed and one dies you lose all your data. It effectively doubles your failure rate.
September 30, 2007 12:39:24 AM

I'm not really concerned about loosing data but I guess you are right, RAM would be the better option especially since I'm currently running 2 x 512mb DDR pc3200 Kingston hyperx ram with a dual core E2140 CPU. Darn, I was so hooked on finally running RAID, ah well... next month, SATA RAID it will be!

Now the question is, which of these RAM will it be? OCZ right? my E2140 is OC'ed to 2.14GHZ (stupid mobo won't let me push it further)
September 30, 2007 11:25:38 AM

RAID 0 in an ideal situation doubles sustained throughput, as you have two disks reading at once, each reading half the data. (assuming you are meaning RAID 0 with 2 disks that is).

It doesn't help seek times, as both heads have to find where they have to start.

As such, 2x160GB drives will always be faster than 1x160GB drive, but its possible that your usage pattern may not allow it to be of full benefit, as you may find that seek is more relevent to you than sustained read.

To be honest though, you would probably be better off with a newer denser PMR drive, like one of the new Seagate 7200.11 500GB/750GB/1TB series, which will probably read faster than a RAID0 of low end 160GB disks anyway :) 
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