We're getting ready to build a new platform for our current system. Currently we install sql server express locally to all our clients and all their data is stored there. While the process works pretty good, it's still a pain to add columns/tables etc. We also want to have our data available outside of the local install. So we're moving to a central web based sql database and creating a web based application. Our new application will be a Silverlight 5, wcf ria services, mvvm, entity framework application
We've decided that either a web hosted sql server database or sql azure database are the way to go. However, I have no idea why I would choose one over the other. The limitations of azure don't seem to apply to us, but our application will be run on our current shared web host. Is it better to host the application on the same server as the database? Do we even know with shared web hosting that the server is on the same location as the app? There's also the marketing advantage of being 'in the cloud' which our clients love when we drop that word (they have no idea about anything technical, it's just a buzzword for them). I'm not too worried about the cost as I think both will ultimately be about the equivalent of each other.
I feel like I may be completely overthinking this and either will work, however I'd like to try and get the best solution for us and don't want to choose without getting some feedback.
In case it helps, our application is mostly dashboard/informational data. Mostly financial and trending data. It's almost entirely read only. Sometimes the data can get fairly large and we would be sending upwards of 50,000 rows of data to the application.
Thanks for any help/insight you can provide for me!
The main concerns I would have with using a SQL Azure DB from an application on your current shared web host would be
The effect of network latency: Depending on location, every time you do a DB round trip from your application to the SQL Azure DB you will incur a 50-100ms delay. If your application does lots of round trips, this will mount up. Often, if an application has been designed to work with a DB on the LAN (you use of local client DBs suggests this) the they tend to get "chatty" since network delays are very small on the LAN. You may find your application slows down significantly.
Security: You will have to open up the SQL Azure firewall to the IP address(es) that your application presents when querying. Depending on your host, it may be that this IP address is shared between several tenants. This would be a vulnerability.
If neither of these is a problem, then SQL Azure will provide a much lower management overhead (e.g. no need to patch etc.) and will give you very high reliability, especially in terms of the risk of data loss.
I am developing a Visual Basic .NET application to be used by the staff of a small training centre nearby. The front-end (UI, menus, etc.) will all be in VB .NET, and there will be a back-end database for storing all of the required data, such as student records and meeting information.
What I would like to know is if it's possible to use a Microsoft Access database for this purpose, and have it accessible by all the staff in the centre (on the same network) at the same time. For example, would I be able to put the database in a shared network folder, and have a copy of the VB application on each PC that would all be able to read/edit/add to the database?
Advice would be appreciated as to how I should proceed. (Note: I would really prefer a method of doing this with MS Access as opposed to suggestions to switch to SQL, as Access was the requested platform)
Thanks in advance.
Yes it can be done and from a programming stand point it is any (much) different then using SQL Server. I think the biggest considerations you have to think about are:
How many simultaneous users do you expect to have using the application?
How secure does the application need to be? Is Access security enough?
How big do I expect the database to become in the next 1 to 5 years?
I think those are you biggest considerations when using Access as a data store and if your answers fall within the specs of Access capabilities then go for it. You can always migrate to SQL Server at a later time if you run into the limits of Access.
You did not mention the version of Access that you are using but a quick Google/Bing search should return specs for every version available.
Yes, but probably not advisable. Despite the disclaimer in your post, you should try to convince the powers to be to look at SQL Server Express instead-- it's free.
But, if Access is the database, all you need to do is have the database reside on a shared directory with full read-write capabilities for all the users. Hopefully when you say "staff of a small training centre", you mean it.
Install the VB.Net program on the client computers and setup the connection string with the path to the database.
Someone else with more recent Microsoft Access experience can probably give better hints on how to reduce the corruption factor. My own experience was to stay away from queries in Access-- have the Access database only for tables and do all of your queries with SQL statements in your client code. My corrupted databases reduced dramatically when I did that, but that was 10-15 years ago.
Back up the database religiously.
Yes, just make sure you chane the extension of your back end access db to your_database_name.be_accdb and it will start logging once the user start writing to it. But I recommend SQL sever
Typically I use a database such as MySQL or PostGreSQL on the same machine as the application using it, which makes access easy and secure. I'm just now building the first site that will have a separate physical database server (later this year it will). I'm wondering 3 things:
(security) What things should I look into for starters pertaining to security of accessing a separate machine's database?
(scalability) Are their scalability issues that I should think about pertaining to this (technology agnostic)?
(more ServerFaultish but related) If starting the DB out on the same physical server (using a separate VMWare VM) and later moving to a different physical server, are there implicit problems that I'll have to deal with? Isn't another VM still accessed via localhost?
If these questions are completely ludicrous, I apologize to you DB experts.
Easy, I'll grant you. Secure.. well, security has very little to do with the physical location of the database server.
To get to your three questions though:
First, look at how you can limit access to database tables using the database servers security model. Namely, if your application does not need to drop tables, make sure the user it uses to connect does not have that ability. Second, look into how to encrypt the connection between the database server and your application. In windows this is pretty transparent through kerberos and can even be enforced by group policy settings, not sure about other platforms. Third, look into what features the database has for encrypting the data "at rest". Meaning, does it natively support encryption of the actual data files themselves?
The point here is that your application is only one possible entry point to the database server itself. Ask yourself, what would happen if someone can connect directly without going through your application using your apps credentials. Next ask, what can happen if they find a SQL Injection issue.. Also, ask yourself, what information can be gleaned if someone is able to monitor the IP traffic going between your app and the server. Can they discern any data? Finally, ask yourself, what if they get a copy of the database itself?
The lengths you go for #1 is going to be dependent on several factors such as How valuable is the data (eg: what would happen to you, your company, or your clients if it was lost); and, How much time do you have to come up with an ideal solution?
scalability: This is purely a function of load. Unfortunately, the only way to scale most database applications is to scale up. Meaning that you acquire a larger database server as the need arises. Stack Overflow went through this not too long ago. Some database types (nosql, mongodb, etc) support a concept known as shredding or sharding. MySql, PostGreSql, etc don't. Instead you'll have to specifically design the app to handle it. Which means not using things like auto incrementing keys, etc. This can be a royal PITA... which is why scaling up is a much easier prospect depending on your application.
Another VM is not accessible via "localhost". localhost defines access to your current server. Whether that server is a VM or not is immaterial. You'll have to reference your database server by name. Now, transitioning the database VM to another physical server should have zero impact as your are referencing it by name. Beyond that there aren't any other considerations.
In addition to Chris's valid response,
Security
Use a security mechanism on the network in addition to whatever security features the database or app framework provides. Perhaps this is a simple as firewalling the network, running IPSEC, or over an ssl tunnel. The point is that you shouldn't assume the DB authors are network security experts, or that the DB authentication mechanism has even addressed network security at all.
Scalability
One scalability issue comes to mind when moving from local to remote dbs. Remote TCP/IP communication is much slower than local pipe communication. Your app may have hidden scalability issues due to frequent round-trips to the DB. Between each query, your app waits for each DB response in succession. On a local system, the latency is so small you may not have noticed it.
Listening to Scott Hanselman's interview with the Stack Overflow team (part 1 and 2), he was adamant that the SQL server and application server should be on separate machines. Is this just to make sure that if one server is compromised, both systems aren't accessible? Do the security concerns outweigh the complexity of two servers (extra cost, dedicated network connection between the two, more maintenance, etc.), especially for a small application, where neither piece is using too much CPU or memory? Even with two servers, with one server compromised, an attacker could still do serious damage, either by deleting the database, or messing with the application code.
Why would this be such a big deal if performance isn't an issue?
Security. Your web server lives in a DMZ, accessible to the public internet and taking untrusted input from anonymous users. If your web server gets compromised, and you've followed least privilege rules in connecting to your DB, the maximum exposure is what your app can do through the database API. If you have a business tier in between, you have one more step between your attacker and your data. If, on the other hand, your database is on the same server, the attacker now has root access to your data and server.
Scalability. Keeping your web server stateless allows you to scale your web servers horizontally pretty much effortlessly. It is very difficult to horizontally scale a database server.
Performance. 2 boxes = 2 times the CPU, 2 times the RAM, and 2 times the spindles for disk access.
All that being said, I can certainly see reasonable cases that none of those points really matter.
It doesn't really matter (you can quite happily run your site with web/database on the same machine), it's just the easiest step in scaling..
It's exactly what StackOverflow did - starting with single machine running IIS/SQL Server, then when it started getting heavily loaded, a second server was bought and the SQL server was moved onto that.
If performance is not an issue, do not waste money buying/maintaining two servers.
On the other hand, referring to a different blogging Scott (Watermasyck, of Telligent) - they found that most users could speed up the websites (using Telligent's Community Server), by putting the database on the same machine as the web site. However, in their customer's case, usually the db & web server are the only applications on that machine, and the website isn't straining the machine that much. Then, the efficiency of not having to send data across the network more that made up for the increased strain.
Tom is correct on this. Some other reasons are that it isn't cost effective and that there are additional security risks.
Webservers have different hardware requirements than database servers. Database servers fare better with a lot of memory and a really fast disk array while web servers only require enough memory to cache files and frequent DB requests (depending on your setup). Regarding cost effectiveness, the two servers won't necessarily be less expensive, however performance/cost ratio should be higher since you don't have to different applications competing for resources. For this reason, you're probably going to have to spend a lot more for one server which caters to both and offers equivalent performance to 2 specialized ones.
The security concern is that if the single machine is compromised, both webserver and database are vulnerable. With two servers, you have some breathing room as the 2nd server will still be secure (for a while at least).
Also, there are some scalability benefits since you may only have to maintain a few database servers that are used by a bunch of different web applications. This way you have less work to do applying upgrades or patches and doing performance tuning. I believe that there are server management tools for making these tasks easier though (in the single machine case).
I would think the big factor would be performance. Both the web server/app code and SQL Server would cache commonly requested data in memory and you're killing your cache performance by running them in the same memory space.
Security is a major concern. Ideally your database server should be sitting behind a firewall with only the ports required to perform data access opened. Your web application should be connecting to the database server with a SQL account that has just enough rights for the application to function and no more. For example you should remove rights that permit dropping of objects and most certainly you shouldn't be connecting using accounts such as 'sa'.
In the event that you lose the web server to a hijack (i.e. a full blown privilege escalation to administrator rights), the worst case scenario is that your application's database may be compromised but not the whole database server (as would be the case if the database server and web server were the same machine). If you've encrypted your database connection strings and the hacker isn't savvy enough to decrypt them then all you've lost is the web server.
One factor that hasn't been mentioned yet is load balancing. If you start off thinking of the web server and the database as separate machines, you optimize for fewer network round trips and also it gets easier to add a second web server or a second database engine as needs increase.
I agree with Daniel Earwicker - the security question is pretty much flawed.
If you have a single box setup with a webserver and only the database for that webserver on it, if that webserver is compromised you lose both the webserver and only the database for that specific application.
This is exactly the same as what happens if you lose the webserver on a 2-server setup. You lose the web server, and just the database for that specific application.
The argument that 'the rest of the DB server's integrity is maintained' where you have a 2-server setup is irrelevant, because in the first scenario, every other database server relating to every other application (if there are any) remain unaffected as well - being, as they are, hosted elsewhere.
Similarly, to the question posed by Kev 'what about all the other databases residing on the DB server? All you've lost is one database.'
if you were hosting an application and database on one server, you would only host databases on that server which related to that application. Therefore, you would not lose any additional databases in a single server setup when compared to a multiple server setup.
By contrast, in a 2 server setup, where the attacker had access to the Web Server, and by proxy, limited rights (in the best case scenario) to the database server, they could put the databases of every other application at risk by carrying out slow, memory intensive queries or maximising the available storage space on the database server. By separating the applications out into their own concerns, very much like virtualisation, you also isolate them for security purposes in a positive way.
I can speak from first hand experience that it is often a good idea to place the web server and database on different machines. If you have an application that is resource intensive, it can easily cause the CPU cycles on the machine to peak, essentially bringing the machine to a halt. However, if your application has limited use of the database, it would probably be no big deal to have them share a server.
Wow, No one brings up the fact that if you actually buy SQL server at 5k bucks, you might want to use it for more than your web application. If your using express, maybe you don't care. I see SQL servers run Databases for 20 to 30 applicaitions, so putting it on the webserver would not be smart.
Secondly, depends on whom the server is for. I do work for financial companies and the govt. So we use a crazy pain in the arse approach of using only sprocs and limiting ports from webserver to SQL. So if the web app gets hacked. The only thing the hacker can do is call sprocs as the user account on the webserver is locked down to only see/call sprocs on the DB. So now the hacker has to figure out how to get into the DB. If its on the web server well its kind of easy to get to.
It depends on the application and the purpose. When high availability and performance is not critical, it's not bad to not to separate the DB and web server. Especially considering the performance gains - if the appliation makes a large amount of database queries, a considerable amount of network load can be removed by keeping it all on the same system, keeping the response times low.
I listened to that podcast, and it was amusing, but the security argument made no sense to me. If you've compromised server A, and that server can access data on server B, then you instantly have access to the data on server B.
I think its because the two machines usually would need to be optimized in different ways. Other than that I have no idea, we run all our applications with the server-database on the same machine - granted we're not public facing - but we've had no problems.
I can't imagine that too many people care about one machine being compromised over both since the web application will usually have nearly unrestricted access to at the very least the data if not the schema inside the database.
Interested in what others might say.
Database licences are not cheep and are often charged per CPU, therefore by separating out your web-servers you can reduce the cost of your database licences.
E.g if you have 1 server doing both web and database that contains 8 CPUs you will have to pay for an 8 cpu licence. However if you have two servers each with 4 CPUs and runs the database on one server you will only have to pay for a 4 cpu licences
An additional concern is that databases like to take up all the available memory and hold it in reserve for when it wants to use it. You can force it to limit the memory but this can considerably slow data access.
Something not mentioned here, and the reason I am facing, is 0 downtime deployments. Currently I have DB/webserver on same machine and that makes updates a pain. If you they are on a seprate machine, you can perform A/B releases.
I.e.:
The DNS currently points to WebServerA
Apply sofware updates to WebServerB
Change DNS to point to WebServerB
Work on WebServerA at leisure for the next round of updates.
This works before the state is stored in the DB, on a separate server.
Arguing that there is a real performance gain to be had by running a database server on a web server is a flawed argument.
Since Database servers take query strings and return result sets, the data actually flowing from data server to web server is relatively small, but the horsepower required to process the query and generate the result set is relatively large. Optimizing performance around the data transfer time therefore is optimizing around the wrong thing.
Regarding security, there are advantages to having the data server on a different box than the web server. Having such a setup is not the be all and end all of security, but it is a step in the right direction.
Regarding scalability, it is easy and relatively cheap to add web servers and put them into cluster to handle increased traffic. It is not so easy and cheap to add data servers and cluster them. Also, web servers and data servers have different hardware needs, so multiple boxes help out with scalability.
If you are starting small and have only one box, then a good way would go would be to use virtual machines. Running the web server and data server in different VMs on one host gives you all the gains of separate boxes at the cost of one large box price.
Operating system is another consideration. While your database may require larger memory spaces and therefore UNIX, your web server - or more specifically your app server since you mention only two tiers - may be a .Net-based, and therefore require Windows.
Ok! Here is the thing, it is more Secure to have your DB Server installed on another Machine and your Application on the Web Server. You then connect your application to the DB with a Web Link. Thanks it.
In a web application architecture with 1 app server (IIS) and 1 database server (MSSQL), if you had to pick one server to virtualize in a VM, which would it be: web or db?
Generally speaking of course.
Web of course.
Databases require too much IO bandwidth + It's easier to add instances or databases to a single instance, whereas isolated web servers benefit more.
Similar question... "Run Sharepoint 2003 on VMWare?". Sharepoint is just an asp.net application with a SQL Server back end.
The shortcoming of most virtual environments is I/O, especially disk. SQL is very I/O intensive. I am using a shared virtual host and the slow I/O is killing me.
That said, Microsoft is pushing SQL on Hyper-V. It's a hypervisor, which means its a thinner layer between the VM and the hardware, and the drivers are quasi-native. Here's their whitepaper: http://download.microsoft.com/download/d/9/4/d948f981-926e-40fa-a026-5bfcf076d9b9/SQL2008inHyperV2008.docx
Looks like for SQL, you will lose ~10% performance overall. The upside is that you can move the whole instance to another box quickly, bump up the RAM, etc.
Another thing to consider is Intel's enterprise SSD drives (X25-E). I imagine that would help a lot in a virtual environment. Pricey, of course.
I would probably decide depending on the amount of computation required by the app server, versus the amount of computation/io done by the database.
With that said I would think most of the time the DB should NOT be virtualized. Virtualization isn't too hot for db's that have to ensure that data remains nice and safe on a disk, and adding another abstraction layer can't help with that.
If you have two physical servers there is no need to virtualise - use one server for IIS and one for the database.
If you have one physical server there is also no need to virtualise.
If I had to choose, it would be the web server. The database would benefit in terms of performance by running on a physical server. If the web server is virtualised, it makes it quick and easy to clone it to create a cluster of web servers.
With today's hypervisors and best practices you can virtualise both infrastructures. When you virtualise your DB infrastructure it is best to ensure that the DB is installed onto a SAN based system so that IO performance is not a bottleneck.
As with everything there are the right and wrong way of doing things but following vendor best practices and testing will enable you to squeeze the best performance out of your VM instances.
There are plenty of whitepapers and performance testing from the various vendors should you want to virtualise your entire infrastructure.
Even though virtualisation again is an industry hot topic with various vendors now giving away hypervisors for free, this does not mean that using virtualisation is the way forward. Server consolidation yes, performance enhancing maybe - YMMV