Web Hosting Talk : Web Hosting Main Forums : Dedicated Server : Raid or not

[barking]

Hello all

I am about to order an additional dedicated server.

The server will be used to put on a large ammount of very small web sites using Cpanel and WHM
It will have a second hard drive for backup.

Could someone give me any info on:


Why i should pay an additional cost for Raid, (my current server runs well without it)

and the difference between Raid 1 and Raid 2


Thanks
Ivaserver

[KDAWebServices]

I am an davocate of RAID, it's saved us many times when disks have gone pop (IBM anyone?). I can tell you the difference between RAID1 and 2 - RAID 1 you will find, RAID 2 you will not find available anywhere, because AFAIK there is no implementation of RAID 2 on any controllers I have looked at because RAID 2 has a prohibitive cost associated with it: http://www.acnc.com/04_01_02.html

[barking]

Thank you Karl for your reply

I made a mistake with raid, it should have been the difference between Raid 0 and Raid 1

Thanks
Ivaserver

[KDAWebServices]

That link I posted has all the RAID levels explained much better than I can do justice too, so I'd certainly recommend you take a read of it.

[sailor]

I agree with kda - linux can even run you a software raid at 0 or 1 level with 2 disks only without hving to invest in expensive raid controller. we recommend it to all our clients. the ones hottest to do it - have just finished losing their data and think it is an incredibly small price to pay for haing peace of mind and their data in tact. funny how that works - it is expensive to do it till you lose your stuff and then all of a sudden it becomes the cheapest thing you could have done. hmmmm......sounds like vegas a bit.

[mgphoto]

I wouldn't run any computer without a raid system, let alone a hosting company. I've seen drives run 4 years with no problems and I've seen two be bad right out of the box. You just never know. If your a professional host you should be running RAID and back-ups.

Does it cost more? Not really. You have 1-3 clients leave because they lost every thing, you have lost the cost of the added hardware. Also add in the fact that you have already damaged the trust relationship with the other clients. Any little problem, your fault or not, and they too will start looking to move.

Michael
http://www.sitesouth.com
http://www.ReSellersISP.com (coming soon)

[panopticon]

Could someone explain the process needed to rebuild a raid 5 array in case of a disk failure? I notice the link above says "Difficult to rebuild in the event of a disk failure (as compared to RAID level 1)"

[panopticon]

I also don't understand this - under advantages for Raid 5 that site says "Highest Read data transaction rate / Medium Write data transaction rate" but then under disadvantages it says "Individual block data transfer rate same as single disk". What does that mean in terms of performance gains in the real world? Is RAID 5 noticably slower than RAID 0?

[ntwaddel]

I would not run any server without a raid. Its just asking for trouble.

[panopticon]

And final question, if I went with a RAID 5 array, what would be the optimal number of disks? I see on pricewatch I can get a Quantum Atlas 10K III 18 GB drive for $91 now. Would it be faster to go with 5 (or more) 18 GB 10K II drives or 3 slightly faster 36 GB 10K IV drives?

[KDAWebServices]

If you go with RAID5 then I would use 4+ drives, RAID5 needs 3 drives to run fault tollerant, so if you loose one drive, you can't afford to loose another.

To rebuild an RADI5 array you need to read in the parity data from the other drives, and construct the file blocks from this parity data and write it back to the new disk.

Write speed on RAID5 isn't all that great most of the time, due to the overhead of calculating parity and having to write the file and the parity data to multiple drives.

Thank you,

[timesroman]

How does write speed of a Raid 5 array compare to write speed to a non-Raid disk?