I hope You remember one of my previous projects — Kitchen PC. It was really great and useful invention, but it became unacceptable as we moved to new apartment. The kitchen here is much smaller and it is absolutely impossible to fit old kitchen PC there. So we lost access to all the movies and music, stored in kitchen PC, but we still want to enjoy them while we are in the kitchen.

So new idea came to my mind. As we do not have enough room to place a big PC in the kitchen, why not to place just a small PC in the kitchen with minimum hardware and deploy some bigger storage separately and provide access to it from the new small kitchen PC.

This is a story about that external storage. Actually this was pretty quick project — it took me one day to make it working and several evenings for light tuning and adding some features.

How Did It Begin

I hope you remember my previous project Silver Box Recorder. It also became useless as Dasha has laptop computer. So I decided to disassemble the Silver Box and use the parts for new project.

I took the motherboard (VIA EPIA M10000), hard drive, fan and some small stuff like buttons, indicators etc. form Silver Box. Actually this motherboard is much more suitable for small home server then for workstation.

I decided that the most suitable place for new storage PC (server) is in the corridor, because there is enough room there and the noise will not disturb us at night.

As in the case with Kitchen PC, I asked my dad to help me — to make a special custom case for HomeServer according to the drafts I prepared using AutoCAD, as usual.

Case Draft In AutoCAD

This time Resin-bonded chipboard (wood chipboard) was chosen as a basic construction material again. I tried to design the case more or less universal, so it can hold up to four hard drives and also has two drive bays for 5.25 inch devices such as full size CD/DVD. I also left some more space for a bigger motherboard, because one used in the project is quite rare in Russia, and in emergency I will be able to replace is with normal micro-ATX motherboard. The case is designed to be used with standard PC ATX power supply and it also no problem to replace it in emergency.

I installed two 80mm intake fans on the front panel. They are located right in front of the hard drives.

Front SIde View

As you can see fans are covered with [white] filtering material. I will tell about this some more below.

Top View

Usually hard drive are one of the hottest part of a PC. And hard drive lifetime is closely connected with its operation temperature. The lower temperature the better. When I was designing the case I aimed to provide the best cooling for the hard drives. Motherboard cooling is not such important for EPIA M10000, as it is designed to produce minimal amount of heat.

Dust Protection

Dust is the enemy of any PC. It covers internal parts, jam fans and cause overheating. Dust is evil! And it is especially important for HomeServer as it is designated to work 24 hours a day, 7 days a week. Here is a method to fight dust that I chose.

The main principals are:

• All intake air should go through filters.
• Total intake fans airflow should be more then total exhaust fans airflow.

Following to these rules gives us a case with higher clean air pressure inside. So dust will not be able to get into the case. I think this is the best strategy in dust fighting and I used the same method in my project.

Air Filter

As it is impossible to buy air filters for PC fans in St-Petersburg, I decided to make them myself. I placed metal net between fans and front panel and bought special filtering material that was originally designated to be used in vacuum cleaners. Then I fixed filter with external grid.

The HomeServer

In Use

This PC is designated to work without keyboard, mouse and display. I connected them only while initial operating system installation. I connected HomeServer with ethernet switching hub, so it can easily be accessed via our local network from other computers in our apartment.

The HomeServer

I also installed a UPS (Uninterruptible Power Supply) to protect the PC from unexpected shutdown because of power failure. This UPS can communicate with the PC and sent proper shutdown command when it is necessary.

Some Thoughts About Digital Data Storage

I installed four hard drives in this PC. This is the maximum number for the motherboard used. One hard drive stores operation system and three other are used to store movies.

I use these tree hard drives as tree separated data storages (they are represented in Windows Explorer as three different drives). The advantage of this type of storage is that all total space of the hard drives is available for data. But this is the only advantage. There are much more disadvantages:

• Not easy to find a file looking through several drives.
• Need to monitor free disk space on several drives.
• Different drives deterioration. Some drives may be used more often then other.
• Non fault-tolerant storage. If hard drive fails — all you have is backup (if you have one).
• Need to have backup.

But everything is not hopeless. There is a technology designated to eliminate all inconveniences listed above. RAID — Redundant Array of Inexpensive Disks (the only lie here is "inexpensive" — hard drives are not so inexpensive, the rest is true). In general, this is a technology of making arrays (groups) of disks to get some benefits of their work in array. There are several RAID levels, representing different types of disk grouping.

For us the most interesting is RAID 5. This technology allows to make an array of tree (or more) drives and gives the following benefits:

• All three disks are represented as a single drive for other programs.
• Failure of one of the disks does not affect the data in the array!
• Equal drives deterioration.

So RAID 5 is fault-tolerant. But how high is the price for this feature?

• All three disks should be of the same size. Or they will become equal to the size of the smallest disk in the array.
• Total space available for data in RAID 5 array of tree disks is not equal to total disk space of all three drives. It is only 2/3 of total space.
• Slightly increased CPU usage during disk operations (but it is possible to buy hardware RAID 5 controller that eliminates this insignificant disadvantage).
• Without hardware RAID controller RAID 5 array is not bootable. So you will need to have one more drive to store operation system.
• Standard features of Windows XP (and below) do not allow you to create RAID 5 array (hardware RAID controller required).

After reading this you may ask: "There are more disadvantages then advantages. Does it worth it?". My answer is Yes.

First: do not forget we are talking about special-purpose PC (though RAID 5 is acceptable for workstation as well). Second: I did not say these are disadvantages. These are features. Lets take a close look at them, starting from top.

All three disks should be of the same size. Yes. It is better to have three equal disks. But if you make RAID 5 of tree disks of different sizes by means of operation system (without hardware RAID controller), you are still able to use the disks space left after RAID 5 array.

Total space available for data in RAID 5 array of tree disks only 2/3 of total space. This is the price for fault-tolerance. But you do not have to worry about your data. If one of the drives fail you will not even notice that. Your data will remain consistent, and you still will be able to read/write data to array. Disk failure is absolutely invisible for user. So it is better to check the state of the disks of the array — to make sure all of them are OK. If one disk fails, you just lose fault-tolerance, but not your data. Fault-tolerance can be easily restored by replacing of the failed disk.

Slightly increased CPU Usage. It is not a problem for a PC, designated to store data, because the CPU in such PC doing almost nothing (I mean file-server). I would call that "putting some useful load to CPU". Not a problem.

Without hardware RAID controller RAID 5 array is not bootable. RAID 5 array is designated to store valuable data, and it is a good idea to separate it from the operation system and programs. It increases overall system performance and data reliability. This is just a proper way.

Standard features of Windows XP (and below) do not allow you to create RAID 5 array. But we are making a server! And it deserves a server operation system (Windows 2000 server, Windows Server 2003, UNIX etc). But if you are a big fan of XP — use hardware RAID 5 controller. No problem.

The HomeServer

So RAID 5 is definitely good method to store your data. Unfortunately the hard drives in my HomeServer project have different sizes and not big enough for creating RAID 5 array. But I dream to make RAID 5 array with new drives some time.

Two Months Later...

After a couple of months I decided to check the air filters. The result you can see at the picture below.

Filters: After and Before

All that dust could be inside the PC. Imagine what would the PC look like inside after a year of operation without filters!

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