Darkstar (.local.DigitalMapping.sk.ca)

This computer was last updated in September 2003. I found a new dual PIII 500. The difference from the last system was faster processors and more memory. The last system was limited to 512MB or RAM. The link to the old system is at the bottom of this page.

This system works as a domain controller (DC) in Active Directory for a private network. It is the only DC so it is the root of the tree. It also supplies DHCP, DNS and WINS services to my small network. It's a mail server, printer server and file server. While I use the builtin SMTP server for email, the POP3 server is my own - check it out here. I also run one SETI client. Granted, the demands of half a dozen workstations certainly doesn't tax the system, but the latter  process keep the processors at 50% all the time.

I ended up rebuilding the the o/s. At first I just stuck in the new board and Windows 2000 just found all the new devices and installed the drivers. The Active Directory (AD) didn't like it however, and just shut down. So I took the opportunity to rebuild the o/s. It probably needs that once in a while anyhow.

Multiple Processors (MPS)

I liked the multiple processors so that was a prerequisite for a new system. The multiple processors don't speed up the system, but probably can handle more small processes like web pages hits and email connections. In addition, if you're buying old technology, (PIII 500's are probably four or five years old) you can get it for cheap. This system, board, processors and 1GB ECC RAM was less than $300.

RAID

RAID = Redundant Array of Inexpensive Drives. Redundant is the key word. If one drive fails, your data is still intact as the RAID will tolerate a failed drive and keep working. Inexpensive is also important, but there are other benefits as noted below.

The RAID works great. On the last system I pulled one of the drives and stuck in a different one to see what happened. The system rebuilt the mirrors with 15 or twenty minutes. It wasn't automatic, but still it worked just fine. I quit using my tape system for backup and just backup my workstation to the server nightly.

On the first system, the RAID was a haphazard arrangement. At first, I just used what drives I had around, then realizing it would work, I bought a couple 20GB drives. I kept the 20GB drives for this system, but borrowed a couple of 40GB drives from my Linux system. I partitioned the 40GB drives so that I had 4x20GB in RAID5 and used the remaining two 20GB partitions for a mirrored system drive. Windows will boot from a software RAID1 (mirrored) drive, but not a software RAID5.

I goofed on the calculations so I ended up with two left over 461MB partitions of the 20GB hard drives. I had to partition the two 20GB for the system mirror first, but that left the remaining partitions smaller that the 20GB drives. Good grief eh. I already had the system built when I found this out, so to use up all the space, I just striped all the remaining space on the drives and called the volume speedy. I don't use it for anything right now.

The other addition, were Promise ATA100 TX2 IDE controller cards. The idea is to keep it cheap eh. The board has SCSI on it, but SCSI drives are twice the cost of IDE drives. I also used Windows 2000 Server software RAID. You can get ATA RAID cards, but they only offer RAID0 (stripping) and RAID1 (mirroring) or 0+1 (sometimes called RAID10). 

Another benefit of RAID is data striping. The data is spread across several drives. The transfer happens in parallel so that means the data is read/written faster then it would be to/from a normal drive. Mirroring is the least efficient redundancy. For every drive you have a mirror drive. RAID5 is the best combination of the two. The data is stripped across several drives and redundancy is achieved with the formula n-1. It only takes one drive for the redundancy so with three drives, 2/3 is used for data and 1/3 is for redundancy. The numbers get better as you add drives.

My drives are ATA133, but the onboard IDE is ATA33. I found the last Promise ATA100 cards for $11 each on eBay. The other thing with RAID is that you want each drive to have a separate channel (no slaves) and preferably separate controller cards. I used just two cards for the four drives. Each is on a separate channel and the Promise cards treats each channel separate so the throughput is 200MB/sec although I think the PCI bus limits it to 133MB/sec. The real downfall would be if one of the cards failed, two drives would be down and the RAID can only tolerate losing one drive.

One note here. In order to rebuilt the RAID system, I ended up destroying any data that was on the drives. I also rebuilt my Linux system (I borrowed two drives from it) but I was able to rebuild it without losing any data.

Overall Observations and Comments

This was just a redo of the previous system so I didn't gain much. Faster processors, more RAM and bigger RAID drives. No new technology. I did learn a think or two. I lost all the accounts from AD which on my small network isn't a big deal. However, had I done that to a real network, I would have been canned.

The proper method (MS recommended), is to add a second DC, demote the system to a member server then change the hardware. Demoting a DC will pass any functions and account information on to the other DC's.

Check out the old Darkstar here. You may also want to look at Wysenburg to see how I replaced the drives without losing the data.