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Old 12-31-08, 07:49 AM   #1
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On a Raid 0 array - How many disks would be Overkill?

Having 2 disks on Raid 0 is fast, real fast. You really notice it when you are dealing with big files, like when you are making a compilation from various family home videos (from the children, nothing frisky). And with 80gb hard disks @ $35 bucks, we can now start thinking about triple or quadruple Raid 0 arrays. But when do I reach the limit? When it becomes so fast that adding an additional disk won't make much of a difference? How do I calculate what's overkill?
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Old 12-31-08, 08:04 AM   #2
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There is no too fast in IT. It's always too slow.
For RAID0 the only limit for disk addition is how much the controller can handle and if the bus is saturated.
But running important data on RAID0 is... uhmmm.. dumb.
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Old 12-31-08, 08:24 AM   #3
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There is no too fast in IT. It's always too slow.
For RAID0 the only limit for disk addition is how much the controller can handle and if the bus is saturated.
But running important data on RAID0 is... uhmmm.. dumb.
Yup, data loss is not funny. But I've a NAS where I backup everything that's important or can't be replaced. Family photos and videos are safe, backed up to a Raid5NAS weekly. On the new rig, I want speed. When I turn on that rid, the case is gonna flex from the sheer torque of the HDs starting to spin.

But I don't know how many disks will it take to saturate the bus bandwidth to the point where an additional disk would be pointless.
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Old 12-31-08, 09:02 AM   #4
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I seriously doubt a single user is even capable of flooding the PCI-E bus.

It would take simultaneous requests from multiple users, such as a server, not an individual machine. That said...RAID 0 is still a bad idea. Look into a RAID 5, or at a minimum RAID 0+1.
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Old 12-31-08, 09:54 AM   #5
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I seriously doubt a single user is even capable of flooding the PCI-E bus.

It would take simultaneous requests from multiple users, such as a server, not an individual machine. That said...RAID 0 is still a bad idea. Look into a RAID 5, or at a minimum RAID 0+1.
I don't know what's the PCI-E bus limit but, is that a bet?

*gets ready to re-encode 1.5Tb of HD Footage*
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Old 12-31-08, 09:58 AM   #6
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+1 on Raid 5. Not that 0 is bad, just 5 is better. And there is no such thing as overkill, or too much, or too fast, etc... with computers.
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Old 12-31-08, 10:07 AM   #7
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So, raid 5 also makes the rig go fast? I thought Raid 5 was more about data security in case of a drive failure, while raid 0 was about speed at the expense/risk of data loss in the event of HD crash.
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Old 12-31-08, 10:07 AM   #8
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Depends on the usage. Also depends on the quality of the hard drives. If you're buying lots of cheap 80 GB drives, are you really going to be better off than buying one Velociraptor? For some uses, yes, but for most cases of an individual user, a single Velociraptor (or two) would make better sense.

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I don't know what's the PCI-E bus limit but, is that a bet?

*gets ready to re-encode 1.5Tb of HD Footage*
Well, a v2.0 16-lane connector can theoretically transfer 8 GB/s. A high end drive can sustain perhaps 120 MB/s. You do the math.
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Old 12-31-08, 10:13 AM   #9
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So, raid 5 also makes the rig go fast? I thought Raid 5 was more about data security in case of a drive failure, while raid 0 was about speed at the expense/risk of data loss in the event of HD crash.
Whether you go RAID 0 or RAID 5 depends on your intended usage. If just using for scratch space for Photoshop, video editing, and what not, just stick with RAID 0 since data security doesn't matter. If using for sustained read/write (as with video editing), RAID 0 with a REALLY good file backup system may make better sense, though you'd better make sure your backups are really good, especially as the number of drives goes up.
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Old 12-31-08, 10:17 AM   #10
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Well, a v2.0 16-lane connector can theoretically transfer 8 GB/s. A high end drive can sustain perhaps 120 MB/s. You do the math.
So theoretically, it would take about 68 high end HD to reach the bus limit... good
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Old 12-31-08, 10:22 AM   #11
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Raid 5 is the best fastest configuration. Suck it up and do a nice Raid 5....it data loss is no big deal and Striped config is best because it is fastest...
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Old 12-31-08, 10:24 AM   #12
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So theoretically, it would take about 68 high end HD to reach the bus limit... good
If you are using a 16-lane slot that's electronically wired for 16 lanes (and not just physically 16 lanes but with fewer lanes wired) and a 16-lane card.
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Old 12-31-08, 10:37 AM   #13
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From another forum I use... this guy has 8 solid state drives on a raid 0... now this is what I'm talking about...woohoo..



Oh, and those who believe Raid 5 is faster than Raid 0... you are wrong but it's a free country, believe it if you want.
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Old 12-31-08, 10:44 AM   #14
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Raid 5 is the best fastest configuration. Suck it up and do a nice Raid 5....it data loss is no big deal and Striped config is best because it is fastest...
Wikipedia: Raid arrays

There are tradeoffs on which raid method to use.

To stream a large file, raid 0 or 5 is fast. Raid 1+0 would be fast and protect from a disk crash, too.

For multiple users reading many different "normal" sized files, Raid 1 is faster on reads than raid 5, since each of the two disks can seek to a different location. This is what the servers at work use, with 100 users and many different applications running at the same time. Most of the reads are accessed from a couple GB of recently read blocks of disk cache in memory, anyway.
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Old 12-31-08, 10:59 AM   #15
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If I had any level of raid it would be for backup, not speed

you'll know what I mean when your drive dies. and it will die someday.
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Old 12-31-08, 11:35 AM   #16
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RAID is overkill for almost all home users. However, you can noticeably improve performance by making sure that disk intensive operations take place on different disks. I hate to state the obvious, but you can also improve performance by using faster disks. A lot of these huge disks are pretty slow.

Even with good backups, I would not use RAID 0. Restoring an entire OS and everything else is a PITA even if your data is safe. If money is not an issue, at least go RAID 1 + 0 or consider SSD for the OS with data files stored on fast disks if they don't fit on SSD.
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Old 12-31-08, 11:38 AM   #17
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RAID is overkill for almost all home users. However, you can noticeably improve performance by making sure that disk intensive operations take place on different disks. I hate to state the obvious, but you can also improve performance by using faster disks. A lot of these huge disks are pretty slow.

Even with good backups, I would not use RAID 0. Restoring an entire OS and everything else is a PITA even if your data is safe. If money is not an issue, at least go RAID 1 + 0 or consider SSD for the OS with data files stored on fast disks if they don't fit on SSD.
The word overkill in a biking forum where 80% of the people own a 5G or more bike. That is a funny word!!!!
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Old 12-31-08, 11:57 AM   #18
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Oh, and those who believe Raid 5 is faster than Raid 0... you are wrong but it's a free country, believe it if you want.
I don't think anyone claimed that RAID 5 is faster...just more secure. RAID O doesn't seem so fast when you're reformatting everything after a drive crashes.
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Old 12-31-08, 01:00 PM   #19
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RAID is overkill for almost all home users. However, you can noticeably improve performance by making sure that disk intensive operations take place on different disks. I hate to state the obvious, but you can also improve performance by using faster disks. A lot of these huge disks are pretty slow.

Even with good backups, I would not use RAID 0. Restoring an entire OS and everything else is a PITA even if your data is safe. If money is not an issue, at least go RAID 1 + 0 or consider SSD for the OS with data files stored on fast disks if they don't fit on SSD.
Not really. Most home users have more demanding usages for their computers than 90% of business machines. Try crunching 100gb of video files. What about copying 1000gb of video files to back up? As for speed, there's absolutely zero chance a single disk can match 700-800MB/s transfer rates of a high-end RAID array.

In the OP's case, I'd go with 4 drives in raid1+0. Drives are dirt cheap nowadays. Your time and labour are not.

BTW - raid-5 sucks for speed, just look up ANY benchmark using same controller and drives.
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Old 12-31-08, 01:07 PM   #20
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Home users' demands are growing, but RAID is still overkill for most users. Backups? Huge amounts of data, but can be run without the user present. Video files? Most users are using DV quality video, which even the slowest hard drives can handle multiple streams of. Final rendering can be done without the user present. I love RAID arrays as much as anyone else, but most people are well served by a single fast drive.
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Old 12-31-08, 01:37 PM   #21
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I know I know... I don't NEED really fast transfers but, is like getting a sport car when the fastest speed limit is the interstate at 65mph... think manly, thing muscle cars, power tools, etc..

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... If you're buying lots of cheap 80 GB drives, are you really going to be better off than buying one Velociraptor? ....
I think so. This 74Gb velociraptor for example, @ 109.99... google around you will find some stats from HD Tune for the drive:



For less than the raptor's price, I could get 3 cheapo SATAs. I don't have anything at hand to make my own test and compare, but I do have an old Raid 0 array (4 years old) on my wife's PC. It was made with a pair of 200Gb barracudas using the old SATA/150 interface:



These 2 old drives already beat the raptor on average transfer rate and max transfer rate. I do believe that a group of 3 new satas could easy beat the raptor on everything. After all, that what RAID is all about, redundant array of inexpensive disks.
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Old 12-31-08, 01:43 PM   #22
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Not really. Most home users have more demanding usages for their computers than 90% of business machines. Try crunching 100gb of video files. What about copying 1000gb of video files to back up? As for speed, there's absolutely zero chance a single disk can match 700-800MB/s transfer rates of a high-end RAID array.
It's true that home use is often more demanding than business use. However, copying large files inevitably involves transferring them across a network or to another device that is WAY slower than that. Also, processing such huge video files are not exactly typical home use.
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Old 12-31-08, 02:25 PM   #23
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Your bunch of cheap drives may have faster sustained performance, but access time suffers when you have a RAID array. Is it worth it? Depends on what you intend to use it for, but unless you have a specific application in mind, probably not since in day to day usage (lots of small files), access time matters just as much, if not more.
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Old 12-31-08, 03:08 PM   #24
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Your bunch of cheap drives may have faster sustained performance, but access time suffers when you have a RAID array. Is it worth it? Depends on what you intend to use it for, but unless you have a specific application in mind, probably not since in day to day usage (lots of small files), access time matters just as much, if not more.
Are you sure? I'm not expert, I'm not being sarcastic or anything, I just have been doing some research for my new rig build and all I've read points to the contrary. On this page for example (scroll down to testing), it shows that the access time actually improved after setting up the raid 0.

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Old 12-31-08, 04:02 PM   #25
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It's true that home use is often more demanding than business use. However, copying large files inevitably involves transferring them across a network or to another device that is WAY slower than that. Also, processing such huge video files are not exactly typical home use.
That's why I have an HP EVA5000 in my closet.
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