Dual Server Configuration Options

[fRAiLtY-]

Hi all,

My company has a HP Proliant ML150 tower server thats going to be a secondary domain controller on a new network/domain. We intend on purchasing a new box to be the primary domain controller. In our day to day business applications we use SQL Server, Active Directory, DHCP and DNS.

Once this new server is in and set we will be rebuilding the Proliant to act as a backup. However what we'd like to do is have them mirrored so in the event of a system critical failure on the new box, the Proliant could take over in the quickest timeframe and keep the business running whilst the new box is repaired.

What would be the best hardware or software configuration to allow this and what are things to be aware of when doing so? My MD suggested one RAID array to service both machines, but I see this as a single point of failure and not a clever idea.

Any suggestions would be great! Both boxes will be running Windows Server 2008 Standard with 25 user CALS.

Cheers.

 

[Showboat]

Assume you want this for a resilient SQL server? Having 2 domain controllers is your AD resilience. (i assume AD / SQL will all be on the same box?)

If you were to use the same set of disks then you would want a standby / recovery server. I haven't seen one of these in about 10 years, but you used to have identical hardware for both servers, if one server failed the other would be sitting at the bios screen ready to boot up and take control of the disks. It would automatically take over in the event of a problem, but if your disks become corrupt you are screwed.

You could build a SQL cluster, but you would need windows server 2008 enterprise for clustering.

2 options, both with cost!

 

[fRAiLtY-]

Hi showboat,

Thanks for the quick reply. We only actually use the free version of SQL Server (Express) as that's all our MIS requires. Also, yes, AD and SQL are on the same box.

My thoughts were replication of the databases onto the 2nd domain controller so in the event of the 1st DC going down we could re-link the client machines to the 2nd DC and away we go. We don't mind a bit of manual intervention (unless there is a hands-off option) we just want to plan ahead just incase.

On the server configuration front, you'd have separate RAID arrays in each DC correct? So effectively they're completely separate entities just both DC's on the same domain.

Cheers

 

[jfish]

why not use DNS as a way for failover

so when secondary (backup) server is kicked into life, just change the DNS entry of the main serve to point to the second server - no other configuration required.

 

[fRAiLtY-]

Hi,

We will have DNS in failover yes, however that doesn't help the SQL situation?

Cheers.

 

[jfish]

Hi,

We will have DNS in failover yes, however that doesn't help the SQL situation?

Cheers.

If existing client use dns name for sql connectivity - then in your case - if server A dies and you bring server B up with the SQL database already replicated - you will just need to change DNS entry of server A to point to server B and on the client side - as the connection to the SQL server is going to Server A, which in turn would point to Server B - or am I misreading what your plan is.

 

[fRAiLtY-]

No that's already what I planned to do.

Have server replication on so A and B have the same data, then if server A goes down, point the clients to server B. I just wondered whether there was an automated solution to this?

Cheers.

 

[jfish]

No that's already what I planned to do.

Have server replication on so A and B have the same data, then if server A goes down, point the clients to server B. I just wondered whether there was an automated solution to this?

Cheers.

Windows clustering or other hardware based clustering/failover, think F5 do a appliance box that does instant fail over without any intervention - not cheap.

only other what I can think of, but may be a bit extreme - is to run some king of perl script to monitor the servers/ports and if it fails then perform the dns change automatically.

 

[soisix]

I would say go Virtual. Go with Windows Server 2008 R2 Enterprise as each license allows 1 physichal install and 4 virtuals.

So get a cheap cost effective iSCSI NAS like the QNAP 809U or smaller depending upon budget and data.

Then just setup 2 x Hyper-V Hosts in a Highly available cluster. Will work well and perform great with no intervention required at client side, and minimal work required on server side should any hardware fail as the VM's will move accross and keep on trucking.

D