Citrix XP data store

[wilsona]

Here's a question that has vexed us:

How can we ensure that the 'Data Store' (required by server farms using Citrix XP) does not introduce a single point of failure into the system?

This seems to be a major blunder by the developers. Any solutions or comments?

 

[CitrixEngineer]

I would tend to agree with you.

CTX625384 sums it up quite nicely - but note the section on indirect and direct connections to the datastore. In an indirect scenario it would appear there are two points of failure; if the one server with a direct connection goes down, the other servers cannot contact the Data Store either.

I note also that "If a member server is unable to contact the data store for 48 hours, licensing stops functioning on the member server. "

Ouch!

I don't think it's a design error, however. "The indirect servers can be reconfigured to point to another direct server by using dsmaint failover."

This looks a reasonable solution, if you're using SQL or Oracle - but a bit messy if you're stuck with Access.

I'm using SQL server 2000, and so far, touch wood, have had no need of a failover - but have configured a test server to double up just in case...

CitrixEngineer@yahoo.co.uk

 

[wilsona]

My point really is why should I have to licence a separate product in order to use this one? What benefits do I get? The old system worked OK. There is now a single point of failure in the system, which was not there before. Unconscionable!

BTW: Replication in SQL Server and Oracle are not ideal or particularly easy and certainly not cheap.

 

[CitrixEngineer]

We're fortunate in that we already use both SQL Server and Oracle for different appplications, so it was just a matter of ensuring we had enough licenses.

I understand what you're saying - a small business can run Access, but it does mean having an extra license for the server. As you say, SQL and Oracle client licenses are not cheap.

For our business, the additional cost is justified by the extra stability, reliability and hence uptime that this setup gives us. Because we're international, this has been the benefit over the old ICA browser model - which could be extremely flaky with high volumes of servers, especially across WAN links. Having said that, I had few problems with ICA browsing in smaller implementations.

I guess Citrix are the best people to ask this question to! CitrixEngineer@yahoo.co.uk

 

[wilsona]

You describe it as stable and reliable - only if you wish to spend a lot more than for the base product (which does not mention the extra cost in any sales blurb...). I would be very interested to hear how you manage the Oracle licenses, because they are over £500 a go, named user only, unless you go for Porcessor Licensing at £28K per processor! (plus a server, plus more for Oracle replication...) If you go the SQL server route you need to buy two extra servers and the Microsoft Clustering stuff to get it going! The words 'rip' and 'off' spring to mind. Are there a lot of Microsoft people influencing (or infiltrating) the direction of Citrix, perhaps? I still see no benefits. We do not have ICA Browser problems, and we have over 40 WAN sites.

 

[Strongone]

Yes I agree it's got very messy recently especially with the changes to licensing by both MS and Oracle.

According to a friend Access makes for a very good data store and is easy to failover and can take large farms- and it's obvious when it's fallen over- you do have 48 hours to make the change which with the correct RM alerts should be easy enough.

We on the other hand use a SQL2000 cluster serving 4000 users worldwide- and yes the cluster is expensive to maintain and build but it is rock solid- however building enterprise database systems for what is a small database is a bit stupid really!

 

[wilsona]

On the Access side - could it be set up as a network share and clustered on NAS boxes? This is the only way I can think of that it will work cheaply and reliably for a small (<3000 user ) farm.

48 hours - What if it fails on a Friday night with no weekend monitoring of systems? Do you come in on Monday morning to a full relicense scenario, and therefore even more downtime?

:-( This is all getting to be too high a price to pay just to give Citrix a nice warm secure feeling. :-(

 

[Jallamann]

I think the alternatives have been covered pretty good here, so just to summarize:
MS SQL/Oracle/DB2: the best choice if you allready have one of these DBMS' in use, considering performance and availability, especially when using some sort of clustering.
Access: Simple to work with, easy to failover, good performance up to 50-60 servers. NB! ALLWAYS back up to an network share with DSMAINT /BACKUP. To answer your question regarding clustering it on NAS-servers: It won't help, since you can't cluster the ODBC DSN on the Data Store server, and therefore have to do a DSMAINT /failover anyway. And if your company do not have any weekend monitoring, your systems obviously aren't so critical that you can't do a failover with the backed up Data Store on Monday morning. And no, there will be no relicensing, because the backed up Data Store has all the license info, which will be cahed on the other servers when they connect to the Data Store again Best Regards
Morten Stårvik
morten.starvik@egroup.no
Egroup Online

 

[steendp]

FYI if you wasn't aware of it.

Since FR2 the 48 hour limit has been changed to 96 hours.
Seems that Citrix now believe we should have some freetime
in the weekends

Regards
Steen

 

[wilsona]

Can anyone tell me how SQL Server licensing will work for this? i.e. do you need a SQL Server CAL for each user on the farm, or for each server that accesses the data store? As I understand it a user is is authenticated by the application server accessing the data store, not the user directly, so all that is needed is a CAL for each application server to the data store, not one for each user.

If the data store is clustered on a NAS box, how does that work licensing wise?

 

[CitrixEngineer]

As I understand it, the Data Collector is the only client of the Data Store, so only one CAL. Gets a bit messier if you have a Summary Database DC set up on a different server to your IMA DC. I always assume one license...

If the Data Store is clustered, I guess the answer must be that you have >1 Database, so the DB license must be >1, even though there's only 1 client.

As far as that Access DS goes, around 3000 users looks quite a lot. My scalabiliy tests showed a measurable performance drop at around 10-12 servers using Access. At c.80 users per server, you're doing very well with c.38 servers...
CitrixEngineer@yahoo.co.uk