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What to store on a RAID 0 array?

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Anonymous
January 13, 2011 4:24:27 PM

Hi guys, I want to use a RAID 0 array with 2 500gb drives to improve performance when using production apps eg video editing and all round general perofrmance.

I was wondering, if something went wrong which caused the array to fail and I had installed my OS on the array, would I have to reinstall the OS and would I lose absolutely everything? If so what is the best way to use a RAID 0 array eg only install applications on it.. any suggestions would be great, thanks!!

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January 13, 2011 4:43:38 PM

You would only want to install/ store data that you do not care about on a RAID 0. If you care about it use a RAID1, you will "lose" 500GB, and the write time will be a little slower, but the read time will be as quick as a RAID 0. In an RAID 1, if a drive dies replace the drive, rebuild the RAID, and you are back up and running.

In production environment, I would go with a RAID 1 hands down... You will get better speeds, and redundancy which you need!
Anonymous
January 13, 2011 7:05:22 PM

Would it be possible for me to run both a RAID 0 and a RAID 1 array on my system. I have ordered a msi-p67-gd65 mobo which has RAID support (I don't intend on buying a RAID add-in card.)

Also would the samsung spinpoint f3's be ok to use in a RAID array or could you suggest any other alternatives?

Thanks for sharing your knowledge tkrl26, you have cleared alot of things up.
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a b G Storage
January 13, 2011 7:37:57 PM

tkrl26 said:
If you care about it use a RAID1, you will "lose" 500GB, and the write time will be a little slower, but the read time will be as quick as a RAID 0.




Correction, the read speed of two drives in a RAID 1 will be nowhere near the speed of those same two drives in a RAID 0. The RAID 0 will be much faster, reads and writes.
a b G Storage
January 13, 2011 7:44:49 PM

You can also create a RAID 10 which combines the performance of RAID 0 with the reliability of RAID 1 but you will need 4 drives. Or you could do a RAID 5 which isnt as fast but gives you more space.
Anonymous
January 13, 2011 7:48:48 PM

mavroxur said:
Correction, the read speed of two drives in a RAID 1 will be nowhere near the speed of those same two drives in a RAID 0. The RAID 0 will be much faster, reads and writes.

I have researched RAID on multiple sites in the past hour and there generally seems to be alot of differing information on the subject floating around, however I have found that most people seem to think that RAID1's read speeds are more or less similar to RAID0 but the write speeds definitely take a hit. But as I say the information out there isn't the most reliable so there's no saying you aren't correct, it's all pretty confusing.
a c 154 G Storage
January 13, 2011 7:52:56 PM

For any dataa that you care about, you need external backup.

Raid-0 is a application performance boost only in limited cases. The OS is not one of those cases.

Read this article, it is a bit old, but still relevant:
http://www.storagereview.com/php/cms/cms.php?loc=news_c...
the relevant conclusion:
"If you haven't gotten the hint by now, we'll spell it out for you: there is no place, and no need for a RAID-0 array on a desktop computer."

I would get a SSD for the OS. If it is not possible to put enough data on the SSD, then
See if you can't arrange to put your source files on one hard drive, and the results on the other. That will reduce access arm contention for sequential operations.
Anonymous
January 13, 2011 8:27:36 PM

geofelt said:
For any dataa that you care about, you need external backup.

Raid-0 is a application performance boost only in limited cases. The OS is not one of those cases.

Read this article, it is a bit old, but still relevant:
http://www.storagereview.com/php/cms/cms.php?loc=news_c...
the relevant conclusion:
"If you haven't gotten the hint by now, we'll spell it out for you: there is no place, and no need for a RAID-0 array on a desktop computer."

I would get a SSD for the OS. If it is not possible to put enough data on the SSD, then
See if you can't arrange to put your source files on one hard drive, and the results on the other. That will reduce access arm contention for sequential operations.

This has confused me even more! However I did manage to find an article that was written in reply to the one you linked http://tweakers.net/reviews/515/raid-0-hype-or-blessing... They show through benchmarks that there is in fact a significant performance increase in raid0 over a non raid set up.

Also, surely the RAID controllers and technology as a whole have improved since the publications of both articles back in '04?
a b G Storage
January 13, 2011 9:00:10 PM

Ok, i'm recommending everyone here go take a class on RAID levels. A RAID-0 will outrun a RAID 1 any day, any time, anywhere, given that they're both built using the same make/model of drives. Data is striped across both drives in a 2 drive RAID 0. A 4 drive RAID 0 would be even better. It doesn't scale 1:1 with drives and performance, because you do have controller overhead, but any two drives in a raid 0 will ALWAYS out the drives if they were run separately. It's not rocket science.
a c 154 G Storage
January 13, 2011 9:40:10 PM

Data transfer benchmarks measure what the benchmark does; large sequential data transfers. They will show impressive statistics. That usually bears little resemblance to what YOUR access pattern really is. A typical desktop user does 90% small(4k-8k) reads and writes,(mostly reads), a task that SSD's are very good at. Raid-0 benefits when a large amount of data is read sequentially. Then there is the possibility that the two I/O operations can happen concurrently.

As an aside, be suspicious of SSD data transfer statistics as a measure of SSD performance. For the typical user, the maximum small random read/write I/o per second is a better indicator. Currently, the best are >50k.

The only valid benchmark would be if you measured your application performance with various storage configurations.
As a small anecdotal experience, I had two Intel X250M 80gb drives in raid-0. Synthetic data transfer rates were impressive. I later changed to a single X25-M 160gb drive and noticed NO difference in what I did, which was mostly internet and typical desktop operations.

Raid fares better if you use a discrete raid card(vs. the chipset raid) that has it's own processor and a fair amount of cache. A good one is expensive, so you need to know that it will do YOUR workload some good.
a c 145 G Storage
January 13, 2011 10:00:30 PM

(R)aid0, there is no redundancy. so AID0(Array of Inexpensive Disks) Is best used where you need top read/write speeds.

Video editing with HD or uncompressed video will see a benefit since the data rates are higher. It is also faster to look through frames in an editor on a (R)aid0 system.

Games that are not heavily compressed also benefit from (R)aid0.

If a game uses heavy compression then the cpu limits the speed at witch data can be loaded and a faster hard drive does not help.

Games with little compression will load faster off a (R)aid0 setup.

Windows generally runs a bit faster and smoother on a (R)aid0 setup.

What does (R)aid0 not help?
Random small read/writes(the they are smaller then the stripe size, they only write to a single drive so there is no speed boost) and situations where an application needs to work with or decompress the data and is limited by the speed of the cpu.

If you use (R)aid0 on windows and one drive fails then yes ALL data is gone, but 90% of the time you will get smart errors reported before it gets this bad. This gives time to get your data off the drive.

I personally use (R)aid0 with 3 x 640 gig WDC blacks for windows and all apps/games. I store files on 2 additional drives(Files and Videos) since they do not need speed and I have a external backup as well for all my files.

One day one of my 640 gig drives started to die, but i was warned in advanced by Intels software(and before loaded the OS) and I was able to get all my needed files from the array. Raid1 while slower would have had no need to backup(see note below), just replace the drive and rebuild.

Since SSD's are not asked in the OP, i will not go into that.

Note: By no need to backup I mean files will not be lost. Important stuff should ALWAYS be backed up in case of on foreseen(i want to say unforeseen consequences, but will not:)  ) deletion from mistake or virus attack.
January 13, 2011 11:02:56 PM

Anonymous said:
I have researched RAID on multiple sites in the past hour and there generally seems to be alot of differing information on the subject floating around, however I have found that most people seem to think that RAID1's read speeds are more or less similar to RAID0 but the write speeds definitely take a hit. But as I say the information out there isn't the most reliable so there's no saying you aren't correct, it's all pretty confusing.


What you are seeing in these reports is the difference in RAID implementation within the RAID controller. Most motherboard and consumer level RAID controllers are fairly simple implementations of RAID whereas server level controllers (read as expensive controllers) have an onboard processor and a much more sophisticated implementation to take into account that there are multiple copies of the data available to read. This approach helps RAID1 setups approach RAID0 setups in sequential read and help them out perform RAID0 in random reads. As you mention they still suffer the slowdown in writes as they need to confirm both writes have completed before signaling success.

The choice of whether or not to use RAID and which levels depends on the applications that you are using (plus the size of your wallet) and how it uses files. I've found that some very good video processing software (as in quality of the video output) which only allows you to use a single volume e.g. the c: or d: drive to store the input, working files and output files. This type software can't make efficient use of any RAID level.

Anonymous
January 14, 2011 7:09:51 PM

I want to thank everyone for doing a super job at clearing RAID up for me, the last 3 posts especially proved really insightful. I apologise for my lack of knowledge causing me to question some replies but I have now bypassed all that. I will certainly use this thread as a reference should I ever get confused again. Cheers!
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