Topic: HDD's and # of clients?

[Jfisher]

Hello everyone, and thank's Apache Lounge. I'm glad this site exist's.

I've ran Apache for a few years now on windows, just simple sites mostly with not alot of traffic. I've been looking into building a newer server machine for a while now and possibly getting more clients for a small side free-lance business.

My current system is 512 mb ram, w2k and 2 IDE HDD's.
Running Apache Php and MySQL. Im looking into making the DB server it's own box aswell as the http server.

I guess my biggest question is, is a raid scsi setup the way to go for me? It's a gray area trying to find info on how many clients each setup could handle and I would like to setup the new machines to be easy to backup, and I have never used a raid setup before. just looking for input on HDD setups and a good way to keep the data backed up and safe in-case of a HDD failure.

Thanks.

[Brian]

SCSI RAID is a great solution for those that have exceedingly high volumes of traffic and where your server will deal with, oh say 10 or more accesses per second sustained, just a number I pulled out of my mind.

My busiest server delivers over 120,000 pages each day and averages about 3.5GB of traffic, again each day. I do this with IDE drives, no raid.

I have RAID 0 on my workstation, using IDE drives, the RAID is hardware built into the MB, and even on IDE it's fast as hell. RAID 0 offers no fault tolerance though, if I lose one drive it's all over.

You have three common options, though many others exist, for RAID.

RAID 0 - striping without parity
RAID 1 - mirroring (both drives literally identical)
RAID 5 - striping with parity

RAID 0 requires at least two hard drives
RAID 1 requires at least two hard drives
RAID 5 requires at least three hard drives

There are solutions that allow you to install a PCI card into an existing MB without RAID that offer hardware RAID. You may want to stay away from RAID 3 and 4, they are excellent for a situation where you are reading large multimedia files (and the likes), but would provide a poor option for a web server.

Yet another option that I am strongly considering is RAID 0+1 which requires at least four drives. Its two striped pairs where the 2nd pair is a mirror of the first. You could lose one drive in one pair and then keep running with the 2nd pair.

Honestly, with the great performance and reliability of SATA, SATA I being 150MB theoretical transfer rate per second and SATA II being double that, you really don't need to consider SCSI, which is ultra expensive and in most instances is not going to help you out.

For a web server though, RAID 5 or RAID 0+1 (also look into RAID 10).

But if you don't see very much traffic, RAID is a nice thing to add, but likely will not help you at all in performance. If you are worred about a drive failing, keep a daily backup but also consider RAID 1 (mirroring).

Hope this helps.

[Jfisher]

Thanks Brian,

SATA RAID 1 sounds like something I would be interested in, I like the idea of having a full time backup running.

Thanks for your input, it cleared a few things up for me.

[Jorge]

[Brian]

One last point, most ISP's use RAID 5, it is faster than RAID 1 or no RAID because it uses striping across three or more drives. But it also offers fault tolerance (parity) so if one drive fails the Array can keep going. It will require you to add another "same" blank drive to replace the bad drive, but it will rebuild the array.

The manner of repairing the array is different for each hardware raid solution, so do your research. BTW, if you are interested I can look up a MB that I found on http://www.newegg.com that is pretty darn cheap and has hardware RAID 5 built in, very cool indeed.

But the really cool thing is if you buy a mb with hardware RAID 5 or if you by a PCI bus card that offers hardware RAID you can then use it with any OS, including non NOS OS's such as XP Pro or 2Kpro.

XP out of the box does not support software RAID 5, though if you do a little Google search you will find that you can hack XP to allow software support for RAID 5 through the Disk Management utility that XP Pro offers.

I don't recommend software RAID, not sure why, just doesn't seem like the best choice.

Finally, if fault tolerance is really important you can go with a version of RAID 5 that with at least four drives you can get the benefit of 3 active drives in the array, and a fourth drive that is running but not used which acts as a hot spare. This is cool because if you lose a drive in the array, it will automatically enable the hot spare, rebuild the array, and then you still could lose even one more drive.

Oh, to get really nuts, you can run a pair of RAID 5 arrays, I think that is RAID 10, just don't remember for sure at this point.

So RAID 1 for simple fault tolerance, and RAID 5 for better performance and fault tolerance.