Hello,

I am working on a linux server mirroring project. The end result would be to have a set of production servers on location A and a second set in location B.

I was originally planning on having the date replicated from A to B nightly. But the company president wants it mirror instantly.

So I have a few options and would like your opinions.

1. Backend SAN's box and switch. The data is sent from the app server to the SAN's switch then to the SAN's box at location A and location B.

2. DFS (Distributed filesystems) - such as OpenAFS.

3. Network raid level 1. - setup a VPN between the machines and then network raid level 1

Please let me know if you have any better suggestions or comments.

Michael

"instant mirroring"? That's going to to be very tricky.

You can set up some WAN based RAID file system. But what will the performance be like?

What is the data you're mirroring. E.g. if it is a database, you may be better off at looking into database replication.

Seriously, you may want to explain the issues to your president. It is a difficulty and complex task (do you have a ton of free time on your hands, or do you have other priorities). Cost is going to be a factor. What are the performance implications.

Make sure that "instant mirroring" is the right solution for your company.

I understand, I do not think that we need instant mirroring, our setup after torromow (because I am making some changes) will be:

--Internet --> load balancing ---> application servers (3x) ---> backend high throughput DB (Oracle 9i).

I am looking into DB replication because it is only the DB that needs to be mirror.

Now I am trying to convincing the Pres.. to buy a SAN's device, for stability and performance, then if we want to we can mirror that device with another SAN's in location B.

But he wants the data to be "instant" for marketing and so location A can handle the east coast and location B can handle the west cost.

I was thinking about ISCSI and mirroring the two DB servers.

I guess we will see - I agree that it will be very expensive because of the cost ($ per GB transfered) to ISCSI the data across a network.

Can you use ISCSI over VPN, since it is IP based ? I would assume yes.

Have you ever considered DRBD for realtime writing to multiple devices in realtime? I was tasked with an HA config for two MySQL servers that require realtime failover capability. I found that using DRBD along with heartbeat was the right solution for me.

Jim