jmc1987

[Log in to get rid of this advertisement]

Hi everyone!

I have been trying to figure out the best setup to run a vps host. Now my question is does 2 HDD raid 10 have the same I/O as 4 HDD in raid 10?

bertl

RAID10 usually means 'striped set of RAID1 pairs'. RAID10 over 2 disks implies 1 stripe of 1 RAID1 pair, e.g. no different from a RAID1 pair.

So short answer: a 4 disk RAID10 will mostly perform better than a 2 disk RAID1, yes.

Longer answer: RAID1 is a mirrored set of 2 disks, presenting itself as one virtual RAID volume. RAID0 is a striped or concatenated set of disks. RAID10 or RAID1+0 is the combination of this: a striped set of RAID1 redundant pairs. The more members in a striped sets, the better performance.

See numerous web pages about this, e.g. http://www.pantherproducts.co.uk/Art...age/RAID.shtml

-Bert

jmc1987

Thanks for the reply.

Okay now for my last questions raid1 mirroring each other for example if you have 2 250GB HD space total 500 GB together does that mean you really have upto 250GB of space and the second disk just mirrors the first disk for a backup if the disk fails?

That is my understanding

bertl

Correct. Two disks of 250G in RAID1 will give you the same net space available as one 250G disk by itself. Four disks in RAID10 will give you 500G.

RAID5 (over at least three drives) gives you more available capacity (2 disks of space out of 3 in the set, 3 out of 4, etc). RAID5 is less straight forward to deal with if there is a corruption problem though, and slower in recovery.

jmc1987

Great just making sure I have a good understanding. I've ran a webhost company before but didnt' use a raid configuration. Which isn't really needed as much. But since I am working on launching a vps company I need disk redundancy because I don't want customers complaining about slow performance.

Sorry one more questions.

If I am using a raid 10 4 disk and 1 disk fails I should be able to throw in a Formatted driver and it should start working with out doing anything correct.

bertl

Then RAID1 and RAID10 will be decent choices. Having redundancy also saves a lot if time when a disk breaks - instead of doing reinstalls and backup restores, you just replace the drive and tell the kernel about it. Often just as important as performance

Electro

For a VPS or virtual machine setup, a multi-disk setup is better than one big disk. Use a disk for the OS and other for storing the virtual machines. This will provide better performance.

RAID-10 is just striping and mirroring. RAID-5 or RAID-6 is striping and parity. Really it is that simple than saying something long that bertl have said. High throughput does not mean high performance. Latency rules performance while high throughput just rules how much data can be copied or written. Using this basis, it is best to use a solid state disk, but I do not recommend NAND Flash memory. DRAM type solid state disk is better.

The difference between the two configurations is the processing power that is needed for each setup. RAID-5 and RAID-6 needs double processing power for the same performance that RAID-10 provides. I suggest use a hardware RAID controller to take up the processing power requirements because this will not penalize the computer.

I would say to use a combination of RAID-5 or RAID-6 and RAID-1. This will give you multiple reads and writes. RAID-5 and RAID-6 can handle multiple writes while RAID-1 can handle multiple reads.

A virtual machine setup requires a lot of RAM and an optimized kernel. The processor does matter if it is capable of handing virtual machine data efficiently. At this time AMD still holds well in the virtual machine department.


Yes, if one drive fails in a RAID-10, you are alright. Two drives could fail if they are adjacent to each other.