RAID0 (2 HDD 5400rpm) vs 1 HDD 7200rpm

[juror1]

I have 2 HDD(5400rpm) in RAID0 .... are they faster than 1 HDD @ 7200rpms 8meg buffer ???

the 2 hdd in raid 0 total 40gig the other is 80gig

 

[Captante]

Yes... the two hardrives in RAID-O should be faster than any single 7200RPM harddrive, provided you configure them correctly, what I suggest you do is use the two 5400RPM drives in RAID-O as your boot drive & then install the 80GB 7200RPM drive as either a master or slave on one of the primary IDE channels on your motherboard & use it as a backup in case your RAID array fails... on most motherboards this should work without a hitch.
One word of caution though... don't try & install an "add-in" drive controller (like a Promise TX2) with the RAID controller, or it will most likely result in major problems.

 

[obeseotron]

That might not be true, a 40 gig 5400 rpm drive is probably from a much older model line than an 8mb 7200 rpm 80 gig drive, in addition the bigger cache and faster access time would play a larger part in everyday usage. The raid might be faster, but only in sequential transfers, and probably not by much even so. I would use the raid for storage and the 80 gig drive as my boot/primary drive.

 

[DJFuji]

Wouldn't the RAID0 only be faster (assuming it is) on data read operations? Because writing still requires standard write operation to two disks. Same speed as single write operation. Read speed, however, should be faster since you can pull data from two sources (using two independent R/W heads).

 

[Double Trouble]

When it comes to RAID, the rpm's play an important part. Yes, your sustained throughput *might* be higher (not sure about that one), but your regular seek times etc are still going to be way slower, and overall performance is likely to be slower as well. You're better off getting one 7200rpm drive.

In fact, I'd say that RAID 0 is pretty much useless on the desktop for the vast majority of people. Sure, there's specific cases where it has benefits, but most users should not be using RAID 0.

 

[StrangerGuy]

Originally posted by: tagej
When it comes to RAID, the rpm's play an important part. Yes, your sustained throughput *might* be higher (not sure about that one), but your regular seek times etc are still going to be way slower, and overall performance is likely to be slower as well. You're better off getting one 7200rpm drive.

In fact, I'd say that RAID 0 is pretty much useless on the desktop for the vast majority of people. Sure, there's specific cases where it has benefits, but most users should not be using RAID 0.

Ditto.

 

[Sunner]

Originally posted by: DJFuji
Wouldn't the RAID0 only be faster (assuming it is) on data read operations? Because writing still requires standard write operation to two disks. Same speed as single write operation. Read speed, however, should be faster since you can pull data from two sources (using two independent R/W heads).

No.
Since you're splitting it up between the two disks, you can write on block to both disks at once.
Hence in theory doubling write speeds.

In either case, the 7200 RPM drive will likely be faster, it'll have much better access times, which is generally much more important that STR for everyday operations.

 

[DJFuji]

Originally posted by: Sunner

Originally posted by: DJFuji
Wouldn't the RAID0 only be faster (assuming it is) on data read operations? Because writing still requires standard write operation to two disks. Same speed as single write operation. Read speed, however, should be faster since you can pull data from two sources (using two independent R/W heads).

No.
Since you're splitting it up between the two disks, you can write on block to both disks at once.
Hence in theory doubling write speeds.

In either case, the 7200 RPM drive will likely be faster, it'll have much better access times, which is generally much more important that STR for everyday operations.

oh wait a minute...i was confusing that with RAID1 (mirroring). So why would pure striping be slower with two writeheads accessing data? Is a 7200 drive THAT much faster?

On the other hand, won't mirroring (RAID1) speed up data access? I'm thinking about running Windows XP off of a RAID of two Raptors to speed up everyday OS performance...

Edit: clarification

 

[Double Trouble]

oh wait a minute...i was confusing that with RAID1 (mirroring). So why would pure striping be slower with two writeheads accessing data? Is a 7200 drive THAT much faster?

I'm not good at explaining, but think of your drive speed being a result of two things. One is how fast the drive can read/write data and send it to your 'puter. The second is how long it takes for the drive to find the data or the right spot on the drive before it can read or write.

Putting someting in raid 0 (striped) mode, you'll effectively double the amount of data the drives can read/write in terms of raw speed. However, the amount of time it takes to find the data/location on the drive does not change. In fact, because now 2 drives have to look for the right spot on the drive to read/write, you have to wait until the slowest of the 2 drives is done, meaning you significatly slow down your performance. So, striping two 5400 rpm drives is a waste of time.

When you use raid 1, you're not striping, you're just reading and writing everything to both drives at the same time. It shouldn't affect your performance a whole lot one way or the other. A raid 1 setup is good for if 1 drive fails.

Also, with regard to striping raptors -- don't do it. Like I said earlier, the vast majority of users do not need raid and raid does not benefit them in normal usage. Take a look at storagereview.com for more details.

 

[A5]

http://www.anandtech.com/storage/showdoc.html?i=2101

 

[Matthias99]

Originally posted by: tagej

oh wait a minute...i was confusing that with RAID1 (mirroring). So why would pure striping be slower with two writeheads accessing data? Is a 7200 drive THAT much faster?

I'm not good at explaining, but think of your drive speed being a result of two things. One is how fast the drive can read/write data and send it to your 'puter. The second is how long it takes for the drive to find the data or the right spot on the drive before it can read or write.

Putting someting in raid 0 (striped) mode, you'll effectively double the amount of data the drives can read/write in terms of raw speed. However, the amount of time it takes to find the data/location on the drive does not change. In fact, because now 2 drives have to look for the right spot on the drive to read/write, you have to wait until the slowest of the 2 drives is done, meaning you significatly slow down your performance. So, striping two 5400 rpm drives is a waste of time.

Yes and no. For 'regular' single-user desktop use, no, it probably won't help you. For something like a transaction database server, where the vast majority of reads and writes will fit into a single stripe (so only one disk has to read or write for each I/O), it can greatly boost your throughput. For something like swap space for a video editing workstation (where you're often reading or writing multi-megabyte or even multi-gig files), it can speed things up considerably, because RAID0 doubles read and write speed for large I/Os. For normal users, you tend to be somewhere in the middle, and then you lose most of the speed advantages, since often both disks are involved for any particular read or write (slowing your seeks down), but the files aren't big enough for the improved transfer rate to really help you.

When you use raid 1, you're not striping, you're just reading and writing everything to both drives at the same time. It shouldn't affect your performance a whole lot one way or the other. A raid 1 setup is good for if 1 drive fails.

With a RAID1 setup, you have to write to both disks, but you can read from *either* disk, and in fact can read different data from both disks at the same time. This makes it outstanding for tasks where your I/O load is almost entirely reads, and most of the reads are small (such as database lookup, or serving up static HTML web pages). It also generally lowers seek times for single-user applications, although it depends greatly on the I/O mixture, and it doesn't help at all for writes (since both disks have to seek to the same block anyway).

Also, with regard to striping raptors -- don't do it. Like I said earlier, the vast majority of users do not need raid and raid does not benefit them in normal usage. Take a look at storagereview.com for more details.

If you're a "regular" user, I agree; the costs are not worth it for the performance. RAID1, however, offers improved data security. There is also RAID5 (although that requires at least 3 disks), which offers the security of RAID1 and the performance advantages of RAID0 (although to a lesser degree).

 

[DJFuji]

With a RAID1 setup, you have to write to both disks, but you can read from *either* disk, and in fact can read different data from both disks at the same time. This makes it outstanding for tasks where your I/O load is almost entirely reads, and most of the reads are small (such as database lookup, or serving up static HTML web pages). It also generally lowers seek times for single-user applications, although it depends greatly on the I/O mixture, and it doesn't help at all for writes (since both disks have to seek to the same block anyway).

Yeah, this is what i was referring to in my first post. The fact that you can read from either disk.

Also, with regard to striping raptors -- don't do it. Like I said earlier, the vast majority of users do not need raid and raid does not benefit them in normal usage. Take a look at storagereview.com for more details.

If you're a "regular" user, I agree; the costs are not worth it for the performance. RAID1, however, offers improved data security. There is also RAID5 (although that requires at least 3 disks), which offers the security of RAID1 and the performance advantages of RAID0 (although to a lesser degree).

[/quote]

I didnt want to stripe them. I wanted to mirror them to protect my data and maybe get a little speed increase from the RAID while i'm at it. (and dont want to shell out loads of money to set up a RAID5). Then again, i'm wondering if it would be better just to get one raptor and back it up every night...

What kind of speed increase will a power user notice? i.e. VS.NET 2003, SQL 2000 test server, Photoshop CS, etc.

 

[Matthias99]

Originally posted by: DJFuji
I didnt want to stripe them. I wanted to mirror them to protect my data and maybe get a little speed increase from the RAID while i'm at it. (and dont want to shell out loads of money to set up a RAID5). Then again, i'm wondering if it would be better just to get one raptor and back it up every night...

What kind of speed increase will a power user notice? i.e. VS.NET 2003, SQL 2000 test server, Photoshop CS, etc.

Visual Studio (I assume you're talking compilation times): probably no improvement, or a very limited one, unless you have hundreds or thousands of small source files (in which case the RAID1 would help). It still has to write all the output (.o, .exe) files back to disk, and RAID1 won't help you there (and, unless your output files are HUGE, RAID0 won't be much help either, since most of these files are fairly small).

SQL server: depends on the I/O load. RAID1 will allow it to do two full-speed reads concurrently (regardless of size), while RAID0 would allow concurrent reads *and* writes if each I/O fits in a single RAID stripe, and would speed things up for large reads and writes (although most databases do very small I/Os).

Photoshop: Unlikely to see any benefit from RAID1. If you work with very, very large files, RAID0 would let you load and save them faster -- but if your files are in the ~1-2MB range, it won't make much difference; you're talking 1/10th of a second as opposed to 2/10ths of a second.

 

[eastvillager]

basically, the articles are saying that ichr5 RAID 0 sucks, not that RAID on a desktop sucks.

 

[Captante]

While I just got done reading the article posted today on Anandtech stating that RAID O makes no performance difference that you can measure, my admittedly non-scientific "seat-of the pants" benchmark results tell a different story *(of course I've been using Promise RAID controllers, so the results may not be directly comparable)... of all the upgrades I've ever made to my computer, none, (with the exception of my first Voodoo 1 in games), has made a bigger difference in my overall system performance then going from a single 120gb SE 7200rpm HD to 2 x same in RAID 0.

 

[Captante]

Whoops... I meant going from 1 x 120gb Western digital 120GB SE 8mb cache drive to 2 of the same in RAID 0, on an Asus A7V333 KT333 motherboard using the onboard Promise RAID controller.

 

[Sunner]

Originally posted by: eastvillager
basically, the articles are saying that ichr5 RAID 0 sucks, not that RAID on a desktop sucks.

It doesn't suck with ICH-R 5, it does what it's meant to do, increase STR, Intel can't do anything about the fact that increased STR doesn't help desktop usage much.