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How to specify the Hardware for a BIM Server
Summary
The BIM server, being scalable, adapts to the hardware it runs on. With the proper hardware the BIM Server response time for any number of active projects can be comfortable for 3, 50, 100, or more users. To achieve the desired performance the following topics, as summarized below, are addressed in more detail in the rest of the document:
Server
Standalone Server - Recommended.
Same physical machine as client - Good for testing, 1 or 2 users with small projects
Operating System
64 bit - Recommended
32 bit - for small projects with less than 5 users
Memory
Acive project size is used to calculate physical memory required
Number of cores
Active number of users is used to calculate the number of cores required.
Data transfer rate between permanent storage and memory
Keep the bandwidth high. Look for solutions tuned to multiuser environments like RAID 10
See also ArchiCAD System Requirements
Standalone server
The BIM Server can run on the same physical computer as ArchiCAD. Though, it is more prudent to run the BIM Server on a standalone server. A standalone server is a machine dedicated to serving data to other machines. It mainly runs processes that do not need a user response, runs a special operating system (but does not necessarily have to), and has hardware better equipped for multiple user network traffic.
For these reasons and others a standalone server is:
- less susceptible to crashes or freezes
- infrequently restarted
- centrally manageable
- able to have faster transfer rates between its network connections and its disks
- almost always online
In addition, a standalone server is more economical. Adding new hardware to the server is essentially amortized over all of the users that connect to it. For instance, if 4GB is added to a client machine it only helps one user, adding the same memory to a server helps all the users that need the server.
The operating system
It is recommended that the operating system be 64 bit, running either Mac OS X or Windows operating systems.
32 bit operating systems have limited memory addressing capability which makes them inherently problematic for the BIM Server. The 32 bit version of the BIM Server is useful when testing or demoing on single machine setups or when a few users will be accessing small projects.
Other operating systems like Linux are not supported.
Memory requirement guidelines (RAM)
Running the bare amount of memory on the BIM Server is unwise. 4 GB of memory is the least that should be considered for a small office and 8 GB is the minimum that should be considered for an average office.
- A safe rule of thumb
- Each shared project with at least one teammate joined will require between 1.5 and 5 times more physical memory (RAM) on the server than the original pln/plp took on the hard disk. How much memory used is file-specific. A 200MB project (pln/plp format) could use anywhere between 0.3GB and 1GB of memory on the server. This memory requirement for practical purposes is not dependent on the number of users accessing the BIM Server.
- Additional considerations
- A server will swap out data from physical memory when the data is not in active use.
Memory requirement calculation
Example 1
- 4 active projects on the server each was shared from its respective 200MB plp
- 10 users access only 1 project over an hour period
- What is the physical memory requirement for the hour period?
- To err on the safe side we use a factor of 5. Each project needs about 5 * 200 MB = 1GB. There are 4 projects so the server will subscribe 4GB of memory for these four projects. 3 of the projects though are dormant from the server's standpoint. The data in physical memory for them will be swapped out to the hard drive. Only 1 GB of physical memory will be needed
Example 2
- 20 active projects on the server, each was shared from 50MB pln files
- 30 users access 10 of the projects regularly within an hour
- What is the physical memory requirement for the hour period?
- 5 * 50MB * 20 active projects = 5 GB. The server will subscribe 5 GB of memory for the 20 projects, but only 10 will be accessed regularly, so the needs of the other 10 will be swapped to disk and only 2.5 GB will be needed.
In both cases a conservative factor and a „normal use” were used to calculate memory usage requirements. The average memory use will probably be less than the above calculations due to the conservative factor used. Optimizations the server employs will also reduce physical memory usage. On the other hand, at some point in the day, for instance, before a planned meeting, a deadline, lunch, or at the end of the day, the intensity of sends and receives and opening other projects may exceed „normal use.” At these special times when there is not enough physical memory, the server will use its disks to store the information. The users will note degradation in performance when this happens.
In example 2, if all the users were to send and receive all of their projects just before lunch the physical memory usage would be 5GB. If the server was fitted with 4GB instead of 8GB, then most of users would witness a slow down.
Fortunately memory is an easy item to upgrade, if your server is frequently using most of its physical memory or performance occasionally suffers, add more memory to the server. It is one of the more important and least expensive elements of the hardware profile.
Number of CPUs
The BIM Server is a multi-threaded application that from the start takes advantage of every core. Commonly a single core will be singled out for the bulk of one user’s ArchiCAD operations. Another user will end up being processed by a different core. The server will balance use across the physical cores. The more physical cores there are the better. A small office should use at least a dual core machine for its BIM Server. Although with the costs of quad cores so reasonable it is hard to justify not starting with a better machine.
From a BIM Server performance standpoint a 2 processor machine runs just as well as a single processor duo core machine.
Virtual cores technology is not yet a proven technology. User experiences in this area are welcome.
Data transfer rate between permanent storage and memory
It is helpful to think of your data being transferred between various holds or caches. There is data kept in:
- Cache memory resting on the processor
- Physical memory attached to the mother board
- Disk storage
- Backup media like CD, DVD or tape.
Cache memory is fastest while backup media the slowest. Per byte cache memory is the most expensive and limited in size, while backup media is cheap and unlimited in size. A computer will run the most efficiently if the processor never has to wait for data. That is, the disk data and the backup media can always keep the physical memory and cache memory full with what the processor needs at any given point. When the processor has to wait for the disks it effectively is doing nothing productive. Unfortunately keeping the processor fed with data is not always possible since it requires the disks know what the processor wants.
There are several subtleties in this area. Disk speed is influential on write and read speed which is also related to the bandwidth of the connection or bus between the drive and the memory. Just as in normal plumbing the size of the pipe influences how much water can flow down it. An external backup drive using USB 2 technology will transfer at best 480 Mbits/s whereas common SATA drives will have a 3000 Mbits/s rating – more than a 5 fold improvement. It comes as no surprise that external USB backup drives cannot be expected to be the best choice for fast data transfer.
Similarly how the data is stripped on the disks, will determine how well the system will work in a multiuser environment. A disk that might appear fast for a single user bulk transfer write becomes wholly incapable of quickly supplying the needs of multiple small data transfers (writing and reading) to many users in a database environment.
There is an art to tuning a server. Often system administrators just settle with common successful solutions. For instance, RAID 10 is an accepted solution for server applications.
FAQ
On a scale of 1 to 10 (1 is least and 10 is most), if the basic filesever (the one most people use to store and retrieve files) works at 5, how hard does the BIMserver have to work. (1 to 10)?
I have a Mac OS X server.
I copied 440 MB of files in a folder on a different machine to the Mac OS X server (file server action)
- Time of transfer: 5 seconds
- CPU usage: 5% max, but average 1-2% cpu usage
I shared a 324 MB pln from the same remote machine’s source folder to the Mac OS X server (BIM Server action)
- Time of transfer: 3 minutes
- CPU usage: 20-40 % CPU usage, average about 25% CPU usage over the length of the transfer
In the example the BIM Server is using about 8-10 times more of the CPU and taking about 30-36 times longer to transfer the data. The BIM Server is not _just_ transferring the data, it is processing it so that clients can access portions of it later. So you pay for the quality of the data processing in CPU cycles and time.
Do you have any real world examples?
From one of our users:
We are looking at purchasing a new dedicated computer to run the BIM Server software (it currently sits on our file server). As part of the process, I've been monitoring our server statistics. The current server is a Mac Pro - 2.66GHz Quad core intel xeon (early 2009 model) with 8GB of ram, and running OSX Server 10.5.8. Observations as follows:
- With our network services, the Wibu server, and the BIM Server running, our CPU usage rarely exceed 20% of capacity
- With all of the above running, most of the time we are using between 7.6GB and 8GB of ram. About 3GB of this is our network services (this was the typical usage before we transferred the BIM Server onto this computer), so that means the BS is typically using 4.5 - 5GB.
- We have 7 projects on the server. The total hard drive space of these and the BS Libraries is about 100GB.
Based on the above, we have decided that the best computer for a dedicated BIM server is one that is loaded up with RAM (I would suggest that a minimum of 8GB is required). The hard drive should probably be about 1TB, and the processor speed can be quite low. For Mac users, the most economical computer that fulfils these criteria is an iMac - 21.5inch / 3.06GHz intel core 2 Duo / 1 TB HD / 8GB ram
Will the BIM Server run on Windows Server 2003?
The BIM Server has been tested in-house on a Windows 2003 server and on Windows 2008 Server. There probably is nothing that will prevent the BIM Server software from running on the Small Business Server operating system, but there are reasons why you might not wish to try.
I noticed on http://en.wikipedia.org/wiki/Windows_Server_2003 that the Small Business Server is limited to 4GB. This memory limitation is definitely a problem. Additionally, the BIM Server is CPU intensive unlike most file servers. So in practice somebody with a Small Business Server 2003 system, would probably be running the BIM Server alongside other resource consuming systems like file sharing, databases, Internet services and the like. In such a scenario the BIM Server would be underpowered.