Raid or two machines for reliability?

duke · 08-13-2004, 03:36 PM

Our company's venturing into dedicated servers for the first time. We want to run our sites and email from it.

Email has gone down twice in the last two weeks with our current shared host so the emphasis is on doing what's needed to keep it going. The sites are important, but not like email.

Looking over the options, we see Raid 1 and two connected servers offered by most places. Can I get some guidance on how to consider these? We'll need to get educated no matter which way we go. Or maybe neither's the answer?

cltwebs · 08-20-2004, 11:15 PM

When you are connecting two servers together you are performing what is called a cluster. A cluster is either two or more servers that are identical in data and configuration. One is primary and other is 2ndary. If one goes down the other takes its place.

RAID 1 is just mirrored drives same data on two drives if one goes down the ther other drive becomes the primary and takes over until replace.

Clusting is more expensive for configureation. Any server IMO should be runing at some sort of raid level.

You are are saying that email went down how did the email go down the app/hardware/network ?

Designing redundancy in server applications such as email is very detailed. But to provide redundance in hardware is much easier. RAID provides Harddisk redunancy and Cluster provides system redunancy.

If your mail app failed neither solution may not even prevented that. could be how the email server was configured or network.

I know does not really answer your question but figuring out how and why went down would be good start and preventing it from doing it again would be first priority if I was maintining that server.

Good Luck

Fusion · 09-20-2004, 05:29 AM

Is that the primary domain controller and bdc?

I, Brian · 09-20-2004, 06:10 AM

Unless you're looking at very heavy server loads, then my inexpert understanding is that RAID 1 with dual SCSI drives will do you great.

Fusion · 10-06-2004, 08:12 PM

Why not SATA, they're cheaper?

littleFella · 10-23-2004, 11:47 PM

SATA disk use main CPU to process data transfer, so they slow down the PC. With heavy disk access the slowdown may be signifficant. Besides, top speed for SATA drive is 10000RPM (only one model in varoius capacities), while top SCSI speed is 15000RPMS with random access in sub 3ms. (sub 5ms for fastest SATA). Especially with software basd (and some cheaper hardware controlled) RAID 5 configurations SATA can be painfuly slow.

SCSI drives on have also their own own processor, so data transfer doesn't slow down the main procesor.

As for the redundancy, for the last 5 years I've been quite happy with RAID 1 on my two home servers. RAID 5 is a little more economical and can be faster, but the speed issue depends on the actual applicaion. it is not always rue that RAID 5 is faster than RAID 1. For instance for database applications RAID 1 may be a tad faster if majority of operations are writes rather than reads.

As far as speed goes, of course RAID 0 is the fastest, but using RAID 0 is ony for those who are not very sentimental about the data they store on their drives. One glitch on either drive means and you kiss your data good bye.

Fusion · 10-25-2004, 05:35 PM

RAID 5 minimum 3 disks

mavwebnet · 06-14-2005, 08:08 PM

Most of our clients just get 2 Hard drives in their dedicated server and configure Mirroring in Windows 2003 Server for redundancy.

Like others posted... this solution would not have helped with your email solution failing. Make sure when you go dedicated you get a stable mail app.