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Redundancy and clustering

By buschman_007 ·
I came into this company and have pretty much overhauled their entire network. Going from an NT environment I have upgraded all their major systems to 2K3 AD as well as Exch 2K3. So the core network itself is running well. But now my thinking is switching over to disaster recovery mode. Pondering about the "what if's". Right now my network relies on tape backup. But I want more safety and less downtime. We have a remote office in NJ(we are loctaed in MD) with a full up T1 connecting us. I'm thinking about server redundancy, but am new to this.

Could anyone suggest the right path to ensuring 0 downtime for servers such as File Servers, Exchange Servers, and DB Servers? What systems would I need to institute to ensure that my users and the outside world never notice a blip on the radar screen?

Thanks for your time and advice.


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by Opiate In reply to Redundancy and clustering

Have you looked into file replication over multiple NAS servers? I am still reseaching because I am in the process of planning the same. But this is one of the solutions I have seen. A few NAS servers that run Hot Swap RAID arrays.

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NAS Servers

by buschman_007 In reply to

No I have not. What is a NAS server and how can it help? Thanks for the heads up.


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Go with Double Take Software

by sarina In reply to NAS Servers

If you go with NAS replication, use Double Take Replication software. it is the best. Definitely don't go with CA or you'll be sorry.

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For realtime file replication -- Double Take

by TomSal In reply to

There is a product from a company called NSI Software, Inc. ( called "Double Take". Its not cheap -- pricing varies on the amount of servers and the OS you are using, but an example of an average Windows server is a retail cost of about $2,000 per server.

However, its made from the ground up for maximimizing server uptime. Its perfect for using with a co-location facility, for total DR security.

What it does (and its fully configurable of course according to how often/how much you want to replicate, etc.) is in REAL TIME it will replicate all changed files to a replication server - this means an EXACT copy of data on replication server as on the production server.

When the production server "dies" double-take, takes over and will switch the appropriate replication server to now be the production server. Downtime is minimal -- definitely less than 10 minutes.

FYI, there is no such as true "ZERO delay" downtime --- UNLESS you have bottomless pockets of course. Most companies do not have that luxury of "money is no object" budgets.

Check it out.

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NAS Servers - What are they?

by gary In reply to Redundancy and clustering

Benefits and Features of the NAS 200m/160GB
Perfectly sized for your small business or workgroup environment, the Iomega NAS 200m/160GB storage server delivers 160GB of RAID-redundant network storage and outstanding performance while easily integrating into your existing network infrastructures - and it's priced affordably too!

Your network can have:

160GB of storage you already know how to use with a Microsoft? Windows? Powered OS
easy installation with plug-and-play connectivity
the best data protection and data storage for your dollar

How Can I...
Add affordable storage to my workgroup?
Your workgroups, remote sites and intense graphics users all need affordable, accessible storage for file sharing and storage. Iomega NAS servers allow you and your diverse workgroups (Windows?, Mac?, Unix, and more) to do just that. High-end graphics, CAD/CAM operators and others can store valuable images on redundant Iomega NAS servers or simply use it as a scratch disk. And, user management rights can quickly be established so data stays safe and protected.

Use my NAS server as an interim backup for tape?
Backing up to a tape drive can often extend beyond the window of time available each night, causing you delays ? and since only one server can back up to a tape device at a time, those delays can be considerable. But there is a better way! Use your Iomega NAS server as an interim or near-line solution to save you valuable time. With NAS, multiple servers can write to a dedicated NAS device simultaneously (and many times quicker than writing to tape), so it doesn?t matter if the tape drive takes all night to backup from the NAS server. Plus, this solution adds another point of failure/protection to your network, and restoration of files from a NAS device is extremely easy and efficient.

Technical Information

Microsoft Windows Powered OS
Microsoft Services for Unix
Microsoft Services for Novell
File Services for Macintosh
Native support of Active Directory Services and DFS aggregation
Computer Associates? eTrust? Antivirus 7.0
Iomega NAS 200m/160GB
Intel P4 Celeron Processor, 1.7GHz
RAID 0, 1
Single 10/100 Ethernet
2 x 80GB Hard Drives, 7200rpm
1U Form Factor
2 USB 2.0 Connections
Service & Support: Limited three year parts and labor, 24x7 telephone support and E-mail with 4 hour response time.

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NAS the cheap way!

by gary In reply to NAS Servers - What are th ...

I currently run a second server beside the critical systems based on a cheap clone which has all the capabilities of a server but is a small portion of the cost. Hourly the systems are syncronised (this can be more frequent if required) and all files co-exist on both systems. AD and DFS are good for this. It's completely automatic. I run Undelete Server on the primary system from where I can recover most inadvertantly deleted files with little effort. This holds multiple recovery versions of the same file so if it has changed 3 or 4 times in a day you can recover them. Deleted is the important point. MDB's for example are never deleted, they are just over written or updated so therefore cannot be undeleted in general terms.
There is some very good software around for making live copies for future recovery and SecondCopy has proved it's worth on many occasions. I am sure there others just as good.

Lots of luck with the thinking.

Gary Stevens

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NAS, SAN and Replication

by ymiheisi In reply to NAS the cheap way!

My understanding is that NAS is suitable for file servers but not databases. We implemented a SAN/NAS solution where we used the SAN for the databases and NAS for files. We are using NSI Double-Take (fantastic software) to replicate locally (for High Availability) and to a remote site (for Disaster Recovery). The software provides automatic failover on the local subnet, but we need to do a few minutes work (changing server names and IP addresses) to failover to the Disaster Recvovey site.

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Other alternative than tape backup

by Joe90Fluke In reply to NAS the cheap way!

Try the Novanet backup made by Novastor.
You can backup to removable hard drives located in an other computer on the netowrk. They provide also an Open File Manager:
I personally backup my Lotus Notes data at the rate of 23 Gygabytes in an hour and a half.
I suggest to always work with at least 2 sets of
I did let go the tapes system a long time ago,
this software I use is a little bit special to configure but it worths the involvment.


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Two sets ? Ahemmm....

by jens In reply to Other alternative than ta ...

Two sets are definitely not enough. Most professionals have one daily, one weekly, one monthly and one set per year to fall back to - often with more sets stored off-site. Also - are they stored in different locations ? What is the cost/gig compared to a very good tape unit ?

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Clustering you said it, Linux will do it !

by mikatrob In reply to Redundancy and clustering

Cluster servers are the only real way to get the 99.9% uptime your asking for, Nas are nice and I personally don't have problems with them except limitations they create. If you can afford NAS units then use real servers and run BSD or Linux on the servers, put your money in mulitple NIC's and Server Hardware with SCSI RAID CONROLLERS, not a IDE raid controller. These systems are inexpensive, then use the DFS since you have MS Win Servers to show the file shares. (Please note: you will have to learn linux to utilize these systems if you do not already use it.) If you use multiple NIC's you can have a dedicated pipe between servers and use replication 24x7 for this and any other data for servers only, then route normal traffice through other NIC in server, also make sure you use switches and not standard hubs. Hubs may be 100Mbit but you must devide the amount of ports into 100 to find the true data rate, switches are inexpensive as well and you will have the redundancy you are looking for.

Linux can function BDC style without problems in the AD setup. If MS systems get hit by virus network stay's up while you take down the AD Server in MS world of AD there is no more PDC/BDC all systems are PDC's again Linux can perform flawless and clustering will out perform the MS systems we already use this set up and save money creating a balance and then the set-up saved us more than once.
Anyone Else?

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