So I took a couple of weeks to go over the problem of my RAID disks being offline or half online or ready but no logical discs ect.
My Failure In Understandings:
I thought that all 6 drives were the same size, but there were three 9 Gb drives and three 25 Gb drives so I will not be able to have more than three discs in my logical drive
I thought that I should be able to configure these RAID arrays from the BIOS or from inside Server 2003 which would be software RAID instead of Hardware RAID
My Confusion In Research: I had three items that came up during boot time and I didn't know which one I needed to learn about to fix my problem.
CH B, SCSI ID: 6 COMPAQ SDT-10000 this was a SCSI zip drive. Irrelevant!
Adaptec AIC-7896 this is the card that the hot swap drives plug into. Still not helpful
IBM ServeRaid 3h this is the huge almst 20 inches long card that actually controlled all the SCSI items. I needed a live cd from IBM to set this up and now I finally found the component that fixed my problem.
I can't stress enough that Google is your best friend, or as my friend Fred commonly mis-quotes me "Everyone likes Google".
My next problem is I am commonly getting a server management controller error. I'm not that worried though because this is the server that gave the school so many fits to start with, it was free to me and I know that it can probably be fixed given enough research.
Finally, the moment I've been waiting for, I have my first server.
As many of you who have followed me over the past year know, I inherited five servers from a school who just closed and have been storing them at my friend Fred's house ( see Holy Man Or Hallucinating Ham for the incredible story of Fred laying on of hands ). So I finally picked up the first of those servers to set up at my house and promptly ran into problems.
We started out with a three disc RAID5 logical disc with 17.8 usable GB. I installed sever 2003 and got all the updates. When I got home I did some investigating and found another logical disc with 69.3 GB offline that was available so I promptly brought it online. Finally I decided to try to merge the two logical discs for one combined 6 disc raid array which would probably have given me roughly a 92 GB logical drive.
Now the first 17 GB logical drive is offline and one of the other disc's read critical and I am having to re-install Server 2003. Now it dawns on me that this might be the same server that kept giving the school all the problems in the first place.
So in addition to finishing up preparations for the studio I am having to learn all about this RAID controller to try to repair it.
CALLING ALL GEEKS AND HACKERS:If anyone knows anything about a Adaptec AIC-7896 RAID controller, send me a comment or use the contact us page at the top. I will be researching this on my own until someone helps me, I find the answer or I get tired and move on to a different server.
So I'm getting ready for the day that painting the basement family room, spare bedroom, and underground lair will be completed. One of the things that I will be doing next is running network cable and creating patch cables to connect my servers, work bench, wireless network and network printer together.
Keystone Outlets: On my main floor I want to have an outlet with two RJ45 jacks for my wireless access point and for my network printer (which is actually a normal printer that I'm using a usb to cat5 converter on both ends and will have it plugged into my print server) This video shows how to punch down a keystone jack and install it in your wall plate.
Patch Panels: This next video shows how to punch down to a patch panel. Why use a patch panel? To keep everything organized and easily rewired for a multiple LAN environment. In my case... why not, it was in the pile of junk.
Patch Cabels: This final video shows how to create patch cabels. Some people use patch cabels for end to end instalation. For most U.S. home and business installations you will use the 568B wiring standard. I have seen that 568A is a European standard and on other sites I've read that 568A is a U.S. government standard. The fact of the matter is that as long as you use the same wiring pattern on both ends of your cable it doesn't matter, but as a general practice I always use the 568B wiring standard.
Ever since I started working in I.T. I've always longed to have my own cool server rack with lots of blinking lights and cables going everywhere. The only problem is that I never had a reason to have a server rack since I didn't have any hardware to put in one.
Well all that's changed now so bar the door and hide the women folk because I have just inherited five servers from a school that just closed. Now that good times are on the way I started shopping for 19 inch metal server racks. With the consumption of steel by China and the U.S. going through the roof, so has the cost of anything made of steel. I will not be dropping $700 - $2000 for a quality steel server rack so I started looking for alternatives. Since Steel doesn't grow on trees I am resorting to the one thing that does... wood.
My inspiration comes from Jeremiah Duke at the missiondukewebsite. You can see his video below.
Now I'm not knocking his design by any means because it fits the bill for him. My design is different in that it's flush on the sides and incorporates plywood shelves for the bottom two levels which is due to the extremely heavy beasts that I'm housing there. The last thing I want to do is get a hernia because the edge of a server got caught on the lip of a 2x4. See my illustration below.
Hope to have pictures of the actual build and the final setup soon.
Now that the Doctor has his own server hardware to use, one of the first things in the installation of either Server 2003 or Ubuntu 10.04 LTS was the use of RAID array drives. For those of you that have never built a RAID array or have heard of them in reference to an existing server but are not sure what they are, let me take some time to explain.
RAID is an acronym that stands for "redundant array of independent disks" or "redundant array of inexpensive disks". Even when the disks are not redundant they may be considered RAID if they work in conjunction to each other in an array.
I will illustrate the most common RAID array and give a brief explanation of each.
This provides improved performance and additional storage but no redundancy or fault tolerance. Any disk failure destroys the array, and the likelihood of failure increases with more disks in the array. A single disk failure destroys the entire array because when data is written to a RAID 0 volume, the data is broken into fragments called blocks. The number of blocks is dictated by the stripe size, which is a configuration parameter of the array. The blocks are written to their respective disks simultaneously on the same sector. This allows smaller sections of the entire chunk of data to be read off the drive in parallel, increasing bandwidth. RAID 0 does not implement error checking, so any error is uncorrectable. Additional disks in the array means higher bandwidth, but greater risk of data loss. Remember with Raid 0, "if you loose a disk you get zero data back"
RAID 1: Mirroring Without Parity Or Striping
Data is written identically to multiple disks (a "mirrored set"). Although many implementations create sets of 2 disks, sets may contain 3 or more disks. Array provides fault tolerance from disk errors or failures and continues to operate as long as at least one drive in the mirrored set is functioning. Increased read performance occurs when using a multi-threadedoperating system that supports split seeks, as well as a very small performance reduction when writing. Using RAID 1 with a separate controller for each disk is sometimes called duplexing. Remember with RAID 1, "One always sees himself in the mirror"
RAID 2: Bit-Level Striping With Dedicated Hamming-Code Parity
All disk spindle rotation is synchronized, and data is striped such that each sequential bit is on a different disk. Hamming-codeparity is calculated across corresponding bits on disks and stored on one or more parity disks. Extremely high data transfer rates are possible.
RAID 3: Byte Level Striping With Dedicated Parity
All disk spindle rotation is synchronized, and data is striped such that each sequential byte is on a different disk. Parity is calculated across corresponding bytes on disks and stored on a dedicated parity disk. Very high data transfer rates are possible.
RAID 4: Block Level Striping With Dedicated Parity
Identical to RAID 5, but confines all parity data to a single disk, which can create a performance bottleneck. In this setup, files can be distributed between multiple disks. Each disk operates independently which allows I/O requests to be performed in parallel, though data transfer speeds can suffer due to the type of parity. The error detection is achieved through dedicated parity and is stored in a separate, single disk unit.
RAID 5: Block Level Striping With Distributed Parity
Distributed parity requires all drives but one to be present to operate. Drive failure requires replacement, but the array is not destroyed by a single drive failure. Upon drive failure, any subsequent reads can be calculated from the distributed parity such that the drive failure is masked from the end user. The array will have data loss in the event of a second drive failure and is as vulnerable as a RAID 0 array until the data that was on the failed drive is rebuilt onto a replacement drive. A single drive failure in the set will result in reduced performance of the entire set until the failed drive has been replaced and rebuilt.
RAID 6: Block Level Striping With Double Distributed Parity
Provides fault tolerance from two drive failures. The array will continue to operate with up to two failed drives. This makes larger RAID groups more practical, especially for high-availability systems. This becomes increasingly important as large-capacity drives lengthen the time needed to recover from the failure of a single drive. Single-parity RAID levels are as vulnerable to data loss as a RAID 0 array until the failed drive is replaced and its data rebuilt; the larger the drive, the longer the rebuild will take. Double parity gives time to rebuild the array without the data being at risk if a single additional drive fails before the rebuild is complete.
In the era of netbooks being used for regular PC's I have come across a support problem of how to install a CD when there is no CD ROM present.
Last year I was working on a computer lab that had multiple PC's that had failed CD ROM's and the solution was exactly the same...
Step1. Share the CD ROM from the host PC. Step 2. Find the host PC's full computer name. Step 3. On the target PC, navigate to the host PC in explorer and double click on the shared CD ROM drive. Step 4. Now treat this directory just like you would a CD drive that is mounted to the target PC.
This is a tool to practice converting
between decimal
and binary representations.
After you have practiced for a while and feel that you know how to do
the conversions, take the quiz.
Image by Jemimus via FlickrBy The Computer Doctor
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