to cluster or not to cluster ????

[David Hodgson]

......that is the question!

I'm putting in a Windows 2003 file/printer server, offline files will
be configured on some of the folders. I need this to be available 24/7.
I can afford downtime but only about 30 minutes max. I'm not that
fussed about peformance.

Now I was going to put in an HP ML350 with redundant Power Supply, Dual
XEON, 1GB RAM, RAID 5 SCSI on an HP 641 Smart Array with about 270GB (3
x 146GB) storage.
Spares = because I have 3 of these servers I can afford to buy 1 CPU, 1
motherboard and 1 Smart Array, these can be used if any of my ML350
servers fail.
Upgradability = can buy another 3 SCSI drives taking capacity upto
730GB.
Cost = £1800 for 270GB, £2550 for 730GB
reason for this server = good reliability, performance and good value
for money.
Partitioning = OS part 1, files part 2
Backup = livestate to restore OS in 20 minutes, veritas to restore
100GB of files in about 6 hours
DFS = could put this in but only the folders without offline files
would work.

Now I'm thinking about a cluster, 2 x (HP DC7600, Single P4, 1GB RAM,
RAID 5 SATA Adaptec card with about 900GB (4 x 300GB) storage.
Spares = none needed
Upgradability = Can change hard drives but these would last 3 years at
current storage usage, I'd rather change the servers after 3 years
before I upgraded the HD's.
Cost = £1700 for 900GB
reason for this server = it's cheap, not bad performance, can hold 4
HD's internally using off the shelf HD's.
Partitioning = OS part 1, files part 2
Backup = livestate to restore OS in 20 minutes, veritas to restore
100GB of files in about 6 hours, although files would still be
available if one server died.
DFS = N/A

Now I have some questions I hope some kind people out there with more
experience than me can help me with...

In your experience is a cluster a good option over a single more
reliably server?
Is there a huge administrative overhead when clustering?
What is disaster recovery like in a cluster, easy, hard?
Would this even work?
Would I need to cluster, what about NLB?
Can I run applications on one server and not the other?
What would you do?
If one server died would the other one still be able to serve users?

I know this is a big request but I really think I can gain more
knowledge from you guys, and it's always a good thing to get the
opinion of other IT professionals.

thanks for reading this far
Dave

 

[Guest]

Clustering is more for Application servers than file servers. They share disk
space so if anything happend to the file structure it would be down no matter
which server tried to access it. Clusters are more intended for stuff like
Exchange or SQL, where if a server fails the second server takes over and
runs the application instead. Since they share the drives the second server
can pull all current config settigns and current data from the array and pick
up exactly where the failed server left off within seconds. I'm not sure if
you can even set up a file server as a cluster, since when you set up a
cluster you also set up what applications to monitor for failover. File
serving is not an app like Exchange or SQL that you can tell to fail over.

As far as other app, yes clustered servers can run additional apps and do
not have to be set to fail over to eachother for all applications. You can
pick and choose. You can set up an exchange cluster and have one machine be a
web server and the other be an SQL server. Wouldn't reccomend it but you
could.

If data access is that critical use 2 servers and DFS. You users will
connect to an AD share and pull files from either server and if one fails
they will all pull from the other.

 

[David Hodgson]

Hi Michael,

thanks for your response, I've thought about the DFS route but I've
heard that if 2 users edit the same file (1 from 1 server and 1 from
the other server) then only one will be kept and the other overwritten.
If I could use this how could I ensure this doesn't happen? also I
cannot use offline folders with DFS so would have to create another
share for offline folders only.

I do like the idea of DFS though.

cheers
Dave

 

[Guest]

Hi David,
There are some safeguards to DFS shuch as a warning if users try to
overwrite each others changes. But you should look into the exact details
before going into production. Also your users will need some training on how
to handle those warnign messages.

As far as offline folders, pointless if you have DFS since they are always
available. On the other hand Offline folders are generally set up on users
machines for files they need access to when not on the network. That you can
still do.

 

[David Hodgson]

Hi Michael,

I like the sound of that but my network is complicated, I have things
like version control software that reside on servers that may not like
DFS, I'll have to test it I think.

On the offline folder side it's more for my sales guys who are rarely
in the office, I've redirected their "My Documents" to point to a
server share, this in turn is offline so when they come into the
boffice their laptops sychronize with the server and their data is then
backed up. Maybe I should think of another way to do this?

What about printer shares? If I had 2 servers would I be able to use
both servers with printers, one maybe a fall back, can Active Directory
do this maybe?

cheers
Dave

 

[m0rk]

Hi Michael,

I like the sound of that but my network is complicated, I have things
like version control software that reside on servers that may not like
DFS, I'll have to test it I think.

On the offline folder side it's more for my sales guys who are rarely
in the office, I've redirected their "My Documents" to point to a
server share, this in turn is offline so when they come into the
boffice their laptops sychronize with the server and their data is then
backed up. Maybe I should think of another way to do this?

What about printer shares? If I had 2 servers would I be able to use
both servers with printers, one maybe a fall back, can Active Directory
do this maybe?

cheers
Dave

I used to do this with the laptops and offline files ... main problem
was we have multiple offices linked via wan and whenever the laptops
connected to the network and could see their server versions although
waaaay across the slow wan link the machines would slow to a crawl on
use.

We now leave the my documents folder as it is in the local profile and
use a file replication software to sync to the server when they choose
to ... they can say no which lets the machine run full speed.

 

[David Hodgson]

Hi M0rk,

can you recomend any replication software I should look at?

Dave

 

[m0rk]

Hi M0rk,

can you recomend any replication software I should look at?

Dave

dont ask ... we're looking at all sorts at the moment ...

allwaysync
viceversa
microsoft dfs and dpm
storagex
rbackup
availl server

im sure ive missed some ...