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Fullmetal Chocobo

Fullmetal Chocobo

Moderator<br>Distributed Computing
Moderator
I'll put together a post for later. I'll start getting together all of my research, and I'll create the thread when I'm able to do all of the benchmarks myself...

 
I'd like to have a definitive answer to whether or not RAID will make a system faster, at least for ordinary 7200rpm drives (I'm pretty sure RAID doesn't help Raptors at all).

EDIT: oh, and I'd also like to know if getting a RAID controller will be worth it for two-drive RAID0, instead of using the onboard solution.
 
Whether using a combination of a controller card, along with an onboard raid controller effects performance or options, in an array of 4 or more drives.
 
Originally posted by: Seekermeister
Whether using a combination of a controller card, along with an onboard raid controller effects performance or options, in an array of 4 or more drives.
Click to expand...

I'm not quite clear on what you mean... If the use of a RAID controller card slows down performance of the motherboard RAID? Or vice versa? Could you clarify a bit?
 
This thread has potential. Not that I personally need any advice on RAID because I don?t, but others could and will benefit from a thread like this.

Kind of make it a WIP thread, and keep updating the OP :thumbsup:
 
Originally posted by: RichUK
This thread has potential. Not that I personally need any advice on RAID because I don?t, but others could and will benefit from a thread like this.

Kind of make it a WIP thread, and keep updating the OP :thumbsup:
Click to expand...

Those that don't need info can contribute and help out everyone else. 🙂 I only have (a lot of) experience with two controllers, and they are PCI-X, which is extremely rare these days. Although I'll be perfectly glad to conduct all of these benchmarks in a month or so when I get my machine up and running.
 
Something I?d like to add about the basic difference between software RAID and hardware RAID before people start chatting about it.

Hardware RAID in its various incarnations will use it own dedicated processor (usually located on the add-in card itself) for RAID array management. Hardware RAID also incurs no overhead on the system processor as does Software RAID.

Software RAID is software designed to run its RAID routines through the system processor (CPU) for RAID array management. The onboard RAID controllers are used for basic hardware routing through the various IDE/SATA channels to manage the logical disks.

Also, Hardware RAID > Software RAID, in all scenarios except for cost conscious users. Onboard Software RAID will usually suffice for simple RAID 0 and 1 arrays however. (Dependent on the implementation and requirements of course).

And another thing, if you?re really looking to get a decent performance boast from RAID 5, you should look into using at least 5 disks due to the amount of I/O operations after each write. Read times on the other hand are awesome.

Fault tolerance and redundancy will be a big talking point too. So dependent on your needs from a RAID array, not one single model is always best suited for you. (i.e. Performance Vs Reliability)
 
I'd like to see something that talks about specific performance benefits of 2,3 and 4 drives in RAID0 versus RAID5. Nforce versus some cheaper SATA raid controllers.

thanks
 
Originally posted by: Cr0nJ0b
I'd like to see something that talks about specific performance benefits of 2,3 and 4 drives in RAID0 versus RAID5. Nforce versus some cheaper SATA raid controllers.

thanks
Click to expand...

I remember that 4 drives (Hitachi 250gb SATA) in RAID 5 was comparable to RAID 0 in performance on a Broadcom BC4852 PCI-X RAID controller. But I'd have to experiment with the other configs.
 
Also whilst I?m talking about RAID, RAID 0 is quite a popular RAID array amongst AT forum goers. What people must remember when setting up RAID 0, is what sort of data access is intended from their array.

The reason I mention this is because you can set the stripe size on a RAID 0 array. You can set the stripe size between 1KB and 1024KB. If your RAID 0 array is constantly accessing small files, a smaller stripe size would be more beneficial, and the same applies with larger files, a larger stripe sector size would be more beneficial.

This is mainly down to the mechanics of the hard disk drive itself. When the needle and head pass over the platters within the HDD, and if you?re reading multiple small files, you don?t want to set a large size sector otherwise the head will read the whole sector even if it doesn?t require all the data from that individual sector, and thus hinder optimal performance on I/O speed.

So for example, if your 1200KB data request was over two 1024 sectors (2048KB total read) instead of say two 600KB sectors (1200KB read) on the same disk, the read access times will be a lot worse as it has to read the extra 848KB remaining on the two 1024KB sectors before it writes that data to the HDD?s buffer. I think people usually opt for around 80KB's per sector maybe more, i can't remember now.

But this is very fine tuning, and obviously you?ll only really notice the performance on a much larger scale in certain read and write scenarios, and benchmarks too.
 
Originally posted by: Fullmetal Chocobo
post your comments
Click to expand...
1. People don't "search" for information they want. They create a thread asking about the topic.
2. RAID information is abundant, if people would simply "search" for it.
3. An "Official" RAID thread would just add to the clutter.
* Don't waste your time trying to cater to the lazy. :roll:
* Learn to use Google, people
 
Originally posted by: Blain
Originally posted by: Fullmetal Chocobo
post your comments
Click to expand...
1. People don't "search" for information they want. They create a thread asking about the topic.
2. RAID information is abundant, if people would simply "search" for it.
3. An "Official" RAID thread would just add to the clutter.
* Don't waste your time trying to cater to the lazy. :roll:
* Learn to use Google, people
Click to expand...

1) Actually, it's catering to us who have to answer questions all the time. All we have to do is post a link to the thread.
2) You answered your own point there.
3) No, it will get thrown down the line like all other threads, but we can reference people to it later.

Bye bye now.
 
If there were a good and thorough raid guide posted, it could be made a sticky at the top of this forum, where it would not have to be searched for and that would be making it better for all concerned. I am fairly new to the nuances of raid, even though I can deal with a basic raid 1 or 0 array, but when it comes to really understanding all of the possibilities, it would require alot of Googling, especially since the forum's search feature doesn't work very well. I understand why some of you would become jaded about answering repetitious questions, but a guide of this kind would reduce that annoyance.
 
The first thing i would like to see is that when people ask about how to set up a raid, a poster doesnt direct them to the wiki raid site that IS COMPLETELY USELESS for figuring out how to install it on their system, what bios settings to use, what harddrives are good to buy, what is the difference between nvraid or silicon..., what stripe size is good for them. Or, something like..."do you still have to install the f6 raid drivers if you have already installed them in an OS on a seperate non raid hard drive?

I think that most people like me who have asked for raid help are trying to get some personal experience from users, or hope that someone has a similar build to help them with certain steps.
 
Originally posted by: supaidaaman
The first thing i would like to see is that when people ask about how to set up a raid, a poster doesnt direct them to the wiki raid site that IS COMPLETELY USELESS for figuring out how to install it on their system, what bios settings to use, what harddrives are good to buy, what is the difference between nvraid or silicon..., what stripe size is good for them. Or, something like..."do you still have to install the f6 raid drivers if you have already installed them in an OS on a seperate non raid hard drive?

I think that most people like me who have asked for raid help are trying to get some personal experience from users, or hope that someone has a similar build to help them with certain steps.
Click to expand...

Okay, I wouldn't point them to the wiki page, but you have to RTFM... There are little difference in every setup (even firmware revisions), and it would be impossible to do a general post for all of them. And I wouldn't do a hard drive selection thing either... The storagereview.com database is more than I could ever muster, and reliability is based on personal experience, and varies widely...

For info on stripe size, I would include--pretty much word for word--what RichUK posted (and of course give him credit for his contribution)...

I'm all for giving information for people looking for experiences and everything, but I refuse to make decisions for people. And if someone is too lazy to read their manual, I can't help them. A question about something in the manual, however, I'm all for trying to help them out...

Anyway, just thought I should put my point of view on that right up front...
 
I'd like to see a clear description of each true RAID setup, including RAID 0 even tho it's not actually RAID. The majority of posts i've seen lately are about "would RAID be good for this" and questions like that. A description of each AND some pros and cons would help clear up redundant posts i believe.
 
For info on stripe size, I would include--pretty much word for word--what RichUK posted (and of course give him credit for his contribution)...
Click to expand...

And this is a perfect example of why ***official*** threads are a dumb idea. Because anyone can post anything without everyone knowing whether this person has any idea what they are talking about or not. Someone comes in and types a whole lot of words in a post and most people automatically assume this person is some sort of expert on the topic.

RichUK is wrong about stripe size, and he uses incorrect terminologies as well. Sectors are 512 byte units of storage on a hard drive, and are not tunable by the user. What RichUK refers to as sectors, are really clusters, which are the basic unit of storage in a file system and can be resized by the user.

His stripe size recommendation is the exact opposite of what it should be. The more small files you have, the larger the stripe size you want and vice versa. This is because a larger stripe size improves positional performance while a smaller stripe size improves streaming (throughput) performance. Simplified example, if you have a four drive RAID 0 array with four 100KB files and a stripe size of 32KB, each file gets split up into 4 parts across the drives. That means, every time you want to read those 4 files, each drive has to search for that 32KB block of each file, for a total of 16 searches, 4 by each drive. If you use a 128KB stripe size, each file is stored on one drive, hopefully a different one for each. If they are optimally stored in, then each drive can search for the one file it has while not worrying about what the other drives are doing. Which do you think is going to be faster? 4 concurrent searches, or 4 serial groups of searches?

For larger files, you want a smaller stripe size because the file will then be split among more drives, meaning the workload is more spread out when long reads/writes are necessary. If you don't keep your drives defragged, this point is moot, because fragmentation will introduce a large amount of random seeking, which nullifies the ability of the array to rapidly stream the data without frequent access time penalties.

The comment about reading extra data into the buffer penalty makes no sense, nor does there appear to be any reason to have made up something like that in the first place.

Most of this information is basically worthless though, because for a 2 drive RAID 0 array which is the RAID setup the vast majority of people here would be using, the stripe size simply doesn't matter, and won't effect performance.

Well, actually, that isn't completely true either. The best recommendation for stripe size is to use whatever the controller defaults to, because that's the value the manufacturer has optimized performance for based on the usage they expect someone using that product to mimic.

This thread serves no purpose when anyone can freely post inaccurate information. Linking to credible sources around the internet provides a far greater service to the readers here than a "if you think you know something, post it here thread."
 
Pariah, im pretty sure i have ready many times and on a few different forums/sites that a larger stripe size is needed for larger files (such as video editing Raid 0 for scratch disks)...

now im confused.
 
Again, from a textbook perspective, the more large files you are dealing with the smaller the stripe size you want. This isn't opinion based, it's simple math. For a 2 drive RAID 0 array in the real world, it doesn't matter. If you are reading a drive full of MP3 files, whether you have an 8KB stripe size, or a 128KB stripe, the performance by a stop watch will be exactly the same. So there is no point in worrying about it. Leave the stripe size at the default size for the controller.
 
I'd like to see a clear description of each true RAID setup, including RAID 0 even tho it's not actually RAID. The majority of posts i've seen lately are about "would RAID be good for this" and questions like that. A description of each AND some pros and cons would help clear up redundant posts i believe.
Click to expand...

as a relative newb to this Forum, i'd have to agree with Blain...this quote is a prime example of ignorance due to lack of motivation to do your own research...word!

what system builders need to do are two things, 1) Google for your answer and 2) RTFM...maybe a little common sense thrown in wouldn't hurt either...
 
Originally posted by: Pariah
For info on stripe size, I would include--pretty much word for word--what RichUK posted (and of course give him credit for his contribution)...
Click to expand...

And this is a perfect example of why ***official*** threads are a dumb idea. Because anyone can post anything without everyone knowing whether this person has any idea what they are talking about or not. Someone comes in and types a whole lot of words in a post and most people automatically assume this person is some sort of expert on the topic.

RichUK is wrong about stripe size, and he uses incorrect terminologies as well. Sectors are 512 bit units of storage on a hard drive, and are not tunable by the user. What RichUK refers to as sectors, are really clusters, which are the basic unit of storage in a file system and can be resized by the user.

His stripe size recommendation is the exact opposite of what it should be. The more small files you have, the larger the stripe size you want and vice versa. This is because a larger stripe size improves positional performance while a smaller stripe size improves streaming (throughput) performance. Simplified example, if you have a four drive RAID 0 array with four 100KB files and a stripe size of 32KB, each file gets split up into 4 parts across the drives. That means, every time you want to read those 4 files, each drive has to search for that 32KB block of each file, for a total of 16 searches, 4 by each drive. If you use a 128KB stripe size, each file is stored on one drive, hopefully a different one for each. If they are optimally stored in, then each drive can search for the one file it has while not worrying about what the other drives are doing. Which do you think is going to be faster? 4 concurrent searches, or 4 serial groups of searches?

For larger files, you want a smaller stripe size because the file will then be split among more drives, meaning the workload is more spread out when long reads/writes are necessary. If you don't keep your drives defragged, this point is moot, because fragmentation will introduce a large amount of random seeking, which nullifies the ability of the array to rapidly stream the data without frequent access time penalties.

The comment about reading extra data into the buffer penalty makes no sense, nor does there appear to be any reason to have made up something like that in the first place.

Most of this information is basically worthless though, because for a 2 drive RAID 0 array which is the RAID setup the vast majority of people here would be using, the stripe size simply doesn't matter, and won't effect performance.

Well, actually, that isn't completely true either. The best recommendation for stripe size is to use whatever the controller defaults to, because that's the value the manufacturer has optimized performance for based on the usage they expect someone using that product to mimic.

This thread serves no purpose when anyone can freely post inaccurate information. Linking to credible sources around the internet provides a far greater service to the readers here than a "if you think you know something, post it here thread."
Click to expand...

On the contrary. This is why things work. It's a matter of being a collection of information from a group contributions. It's when no one contributes that nothing is learned.

Thanks for the bump, despite a good attemopt of thread crapping... That is the reason people don't do posts like that. Because people just have to be a$$hats, instead of just saying "no, that's isn't correct. Read this:".
 
Originally posted by: Fullmetal Chocobo
Originally posted by: Seekermeister
Whether using a combination of a controller card, along with an onboard raid controller effects performance or options, in an array of 4 or more drives.
Click to expand...

I'm not quite clear on what you mean... If the use of a RAID controller card slows down performance of the motherboard RAID? Or vice versa? Could you clarify a bit?
Click to expand...
I guess it doesn't matter too much, because I'm learning the answer by trial and error. It wasn't whether the controller card would slow down a motherboard, but whether there is any differential in performance between a raid controller card vs an onboard raid chip. It's too early for me to make any declaration, but with my cheap controller, it appears to be slightly slower than my onboard raid. That's probably just due to the quality of the controller.

The controller is supposed to be able to do 0 + 1, but all that it has that isn't greyed out in the menus is simply 0 or 1, but that may be to a lack of HDs. But, if the onboard raid is either 0 or 1, and the controller card is able to do 0 +1, can I assume that the controller card would be able to utilize both arrays together?
 
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