I am preparing to setup two Linux servers, using them as Network Attached Storage. I need to have these two servers mirror each other, keeping all of their files updated in a realtime basis. Does anyone know of a good How-To on this subject or a software product that will enable this type of function???


Thanks

Are you trying to RAID them? try this link and see if that is what you're looking for:

http://linas.org/linux/raid.html

Hope this helps

Rye,
Thanks for the doc's, have reviewed them. They do contain useful information, but I don't think I will be able to use them. Currently the two servers I am working with will be running RAID level 5 at the hardware level. I am looking for something that will allow me to keep these two servers in sync in a real-time basis...... They will be located in two separate locations, connected via a dedicated line. So, I don't have to worry about performance of this dedicated link, as the servers will be the only traffic on this link. The dedicated link will be running on a separate NIC also. I don't care if I need to purchase a vendor package, i do need one that is stable.

On another note, if anyone knows of a package or way of load balancing between two servers, any info????

John

I am not sure that real time mirroring is possible with just two linux servers, especially if you want to add in load balancing. I think you could achieve close to real time mirroring with rsync and an agressive cron schedule but it would take quite a bit of processor power; possibly degrading the other services you are offering. To load balance, you would definately need to throw aonther box on the path.

Maybe there is another solution that is less agressive. Why do you need to have real time mirroring? DO you have any other computers at your disposal?

I know that redhat enterprise is well suited to your specific needs... might want to check out thier info.

Try this stuff out: http://lcic.org/load_balancing.html

As far as having the machines mirror each other, parhaps there is some way you could trick nfs into do it.

Ezra143,
Mirroring has been requested by the end user, so it's not really an option. I will check with Redhat, regarding the Enterprise Edition of their package. I was looking in that direction, so this shouldn't be an issue (I hope). As for using the Rsync function, based on the amount of time and the amount of data that would be involved, it is not an option. As I mentioned we are currently running RAID level 5 on both of these boxes. The client wants total fault tolerance, no outages will be tolerated.


John

jtshaw,
Thanks for the info, I will look into the different methods and products listed on that page. Either you or Ezra143 mentioned using additional systems to enable some of these services. At this time, I will begin this project by first getting the severs up and running and mirrored. Following that I will begin the pursuit of doing the load balancing. See I didn't mention it, but the clients currently use Windows machines and I was looking towards Samba for access. I have used Samba before with very good results. So as they say, "Staying with what has worked for me before." I know this site has me listed as a newbie, but I normally find my own resolutions to problems. Thanks again for the lead. If anyone has any additional ones please post them, as I am never closed to a new idea or way of doing something. Thanks

John

Sounds like quite a project, But I'm sure Redhat can manage it for you using LVS, Samba and so on.... best of luck. Keep us posted on which direction you go..Sorry I couldn't be of more help.

I might have some good news for you, John. I am using mandrake 9.2 and have a app called LinNeighborhood installed. It lets me log into my winxp via my local network (similar to network neighborhood, go figure). Anyway, when you connect to another computer, it creates a mount point in a folder of your choice. From there you could follow the RAID 5 how-to from the following link:

BTW If you try using LinNeighborhood, give it a second or two to connect to a Windows comp. Once it is connected, it will remain connected until you unmount it. Plus, it uses a Samba port (139)

http://www.tldp.org/HOWTO/Software-R...O-5.html#ss5.7

Hope this helps!

ezra143,
I have contacted Redhat, they recommend setting up Linux Clusters. (Kind of what I had in mind). Based on the white paper that I have reviewed, I would use the two severs that I have as Network Attached Storage. I would then, setup two servers, using cluster technology, to mirror each other. This isn't exactly what I had in mind, but it would work. I would then have the two Clustered servers mount the Network Attached Storage at whatever mount point I choose. If one of the Clustered servers does go down, the other would pick up the connection... I was hoping for a little different approach. I was looking for something more along the lines of a real-time file replication package. In years past there was a product, used on Novell servers that did something like this (tried to recall the name, went blank).

John