RAID Backup

Working perfectly!

Usually, a person needs a backup when their disk drive fails. All disk drives fail sometime - there is no escape from that truth. But there are other reasons for keeping good backups:

• Total disaster, such as a fire or flood that destroys the whole computer and all nearby backups.
• Deliberate mischief, such as a virus that deletes important files.
• Accidental deletion or modification of one or more files.

I'm sure there are more reasons, but if we cover these we'll probably have the rest covered.

Drive Failure:

Disk drive failure can mostly be avoided by using two mirrored drives in a configuration known as RAID 1. RAID means Redundant Array of Independent Drives, and has several well-defined levels. RAID 1 is a simple comfiguration with two drives which always contain exactly the same information, hence the term "mirrored." If either drive fails, the other simply becomes the system's sole drive and takes over without a hitch. Since the probability of two drives failing at once is very small, RAID 1 pretty well covers that problem. The new computer here employs RAID 1.

Total Disaster:

If the building burns down or floods, the only solution is to have a separate backup stored offsite. This can be on the internet, another building some distance away, or perhaps in a fire- and water-proof safe. At this office a flood is highly unlikely, so we store encrypted DVD backups of most user files in a fire-resistant safe in the basement, and we occasionally put a DVD in a safe deposit box at the bank. I have just set up an upload account and I may stop putting DVDs in the safe deposit box. We'll see.

Deliberate Mischief, or Accidental Deletion or Modification:

RAID disks don't help here, because the RAID disk controller keeps the two mirrored disks identical even when the files themselves are deleted or corrupted. This is where Windows System Restore can be very handy indeed. I have several times seen a serious problem solved by restoring a system to a previous date and time. System Restore works, though it has the disadvantage that the whole drive reverts to a selected time in the past, even if you only need to recover one file.

But if System Restore isn't the solution, then backups are the answer. DVD and internet backups can be used to restore user data, but what about all of the rest of the system? I started a full backup once, but quit when the backup wizard pointed out that I would need 19 DVDs. Enter "RAID Backup" with a third identical disk drive. At some reasonable interval (every day, every week, every month) I can disconnect the power to one of the two mirrored disks and connect the third disk. The disconnected disk is instantly a complete backup of everything, and the newly-connected disk will soon be overwritten and re-mirrored to the remaining good disk in the RAID 1 pair. Voila - complete backup in about five minutes for a one-time cost of about $80. It does actually take about 2 hours and 15 minutes to re-mirror, but the system is usable, if slower, while that takes place. And the third disk, with no power, is safe from any mischief.

It Works!:

I wasn't entirely sure that the Intel software would be totally cool with what I wanted to do, but I tried it last night and today. The system has three identical 320 Mb Western Digital hard disk. Steps in the experiment:

• Disk Drives A and B were mirrored, drive C was powered up as a spare but had never been used.
• I shut down the computer, disconnected power on B, rebooted the computer. The Bios complained that the RAID 1 pair was "degraded" and gave me a chance to deal with it in the Bios, but I declined and let the bootup proceed.
• The computer booted normally, and the Intel monitor software presented a pop-up balloon that said the RAID 1 disk was degraded but could be repaired.
• I clicked on the balloon and followed the instructions to restore disk C to mirror the good disk in the RAID pair, disk A. Two and a quarter hours later, A & C were a mirrored RAID pair and B was a complete backup. Job done.
• As an experiment, however, I shut down again and disconnected all EXCEPT disk B, then rebooted. Again the Bios complained and the on-line software did too, but the system functioned normally on just the "backup" disk. As far as I could tell, all files were accessible. The RAID software, apparently confused, also created a second RAID array at this point, consisting of Disk B and a "missing" disk. Duh.
• I rebooted with only A & C connected, and everything worked once again, no complaints.
• Then I connected B as well, rebooted, and got some complaints about a degraded pair in the second RAID array (disk B), but the system ran normally and all files on all disks seemed to be accessible, including the files on disk B.
• Finally, I disconnected disk C, leaving A & B connected, and rebooted once again. The Bios and the Intel application software both complained about degraded RAID arrays. But it allowed me to delete the second RAID array, consisting of only disk B. That done, it allowed me to re-mirror B to the good disk in the original RAID pair, disk A, even though disk B contained lots of valid data. I was concerned that it might not let me destroy data, and I think there were at least four warnings that data would be destroyed on disk B if I proceeded, but it finally let me do it. Now disk C is again the full backup and the system is back to a RAID array of disks A & B.

From now on the procedure will be much simpler: Shut down, disconnect B or C (whichever was connected), reconnect the disk that was disconnected, reboot, and tell the Intel application to restore the RAID array. The biggest hassle is moving the computer to a position where I can open the side panel and disconnect / reconnect drives. I can handle it.

Windows Experience Index:

Before these little experiments, the system's Windows Experience Index was 5.4, limited by the disk subscore of 5.4. I ran the tests several times. Since the experiments, the Windows Experience Index is 5.5, limited by both the processor and gaming graphics, with the disk subscore improving to 5.7. Why did the disk subscore go up from 5.4 to 5.7, using exactly the same disks? Only Microsoft knows.

The Computer Is Built!

And I'm pleased with it.

Performance:

The overall Windows Experience Index is 5.4, which I believe is pretty good. The limiting subscore (5.4) is the disks, actually, and they are very high-speed SATA II 7200-RPM drives, though you can get 10,000 RPM drives which should be faster yet. The highest subscore is the Windows Aero graphics, 5.9. Everything else falls between, so the system is reasonably well balanced.

Quietness:

When there is nothing else going on in the room, TV and the old computer turned off, sitting at my desk, I can hear a faint, low-pitched roar similar to the sound you hear by holding a large seashell up to your ear, but certainly not that loud. It has a resonance to it, despite my efforts to dampen sounds inside the box. I think that the rear fan is the origin of most of the noise. It's not objectionable, because it's faint, but I will probably try to do more to limit the sound, such as:

• Add more sound-deadening material inside the box; there is room on the side cover for more;
• Play with fan speeds. The computer reports its own temperatures at several places including the CPU, graphics card, and motherboard, and those are quite comfortably within spec right now, so I could choose a lower speed for the rear fan;
• Cover the strange hole pattern on the back of the case, for which there seems no purpose; and
• Replace or rewire the rear fan. The motherboard came with a fan-control connection for that fan, but oddly, that fan did not come with a connector for the fan control. It may be easier for me to order a fan with the right connector rather than a conversion cable.

Bottom Line:

It's a good computer. Luckily there were no DOA (dead-on-arrival) parts, and it came right up and ran. The only problems were software ones, after Vista was installed and not to be discussed here (though I may yet post a rant about Vista. It is SO awkward and obtuse). I think that once a person has the proper parts on hand, one could put a computer like this together in an hour or two, including the initial Vista installation.

Below is a pictorial of the build process, in reverse order. Click on the Materials List on the side panel to see what went into the computer.


After powering up the disks, this screen in the BIOS allowed the association of drives A and B as a single fault-tolerant 320 Gb RAID disk before anything was ever written to the disks.


When first powering up the system, I had disconnected all of the disk drives and some other stuff to see if the CPU and motherboard would POST (power-on self test). THEY DID! This screen proves that a lot of stuff was working:

• Power supply;
• Motherboard;
• CPU;
• Graphics card, at least sufficient to display to the generic screen; and
• USB ports and keyboard-handling firmware on the motherboard;
• Fans (I could see them turn).

The box is fully wired and ready to test.


The motherboard is installed and screwed in place.


The three 320 Gb hard drives are in place and wired up. Two drives are for the fault-tolerant RAID disk, and a third will be used as a backup.


It's still hard for me to reconcile this palm-sized, silent, extremely fast 320 Gb drive with the washing-machine-sized sub-Gb drives I cut my computer teeth on years ago. And in just a few years, even these will be replaced with much faster flash drives having no moving parts at all.


Sound-deadening material stuck to the back side of the hard-drive cage. A similar piece is attached to the side door covering the drives on this side, and on the bottom and top of the cage. I attached this material on all interior surfaces wherever it could be attached without getting in the way or interfering with the passage of cooling air.


Sound-deadeing felt. Found in the local Menards hardware store, not for the purpose of deadening sound, but I think it should work. I liked the black better, but the store didn't have much so I bought some of both.


Front fan installed inside of the hard drive cage, to pull air across the drives and blow it toward the graphics card and CPU. See earlier posts for other views of the entire case.

RAID

RAID is a computer acronym meaning "Redundant Array of Independent Disks." Wikipedia. In this case we're talking about "mirrored" disks, one of the simplest RAID configurations, where two identical disks contain identical data so that one can continue operating if the other fails. Since they contain the same data the second disk doesn't add any disk capacity, but it does add reliability. Pros:

• The hard disk is MUCH less apt to crash. Only people who have experienced a crash can fully appreciate this.
• Perhaps I can get away with less backup, e.g. only back up the most sensitive data.
• Or, I can buy a THIRD drive and hot-swap it, so the swapped-out drive is the backup.
• I'd enjoy the experience of setting it up and using it.

Cons:

• It's more expensive: I need two drives, not one, and the motherboard (which manages the drives) costs a little more.
• The drives will make twice as much noise. Hmmm.
• It doesn't solve ALL backup problems: If I accidentally permanently delete a file, it will be gone on BOTH drives; if lightning hits the computer it could easily take out both drives.

I'm leaning toward RAID, as you may have guessed. But haven't decided yet for sure. Seems like overkill for a simple office computer. But then again there's the experience of it ...

Here are some other features of the computer that's starting to come together:

• Sonata III 500 case, with 500 W power supply. This is the outer box for the whole thing, and this box is quiet with plenty of power available.
• Intel E6750 dual-core processor, 2.66 GHz, 1333 front-side bus, with Intel motherboard to match. This is two very fast processors in one. By the time I get going on this, the E6850 may come down in price, even faster.
• 2 Gb of 2-channel DDR2 memory, 800 MHz. Expandable to 8 Gb they say, but the chips for that don't exist yet; 4 Gb is the max.
• Seagate 320 Gb SATA-300 drive(s). Big enough for me.
• Sony AWG170S-B2 18x DVD read/write.

But everything is still in pencil. Absolutely everything. Meantime, though, I did a little pricing of the materials lists for WITH RAID and withOUT RAID. Here are very preliminary materials lists:

• With RAID.
• Without RAID.

I'm totally new at this, a complete novice. If there is anyone out there reading this blog with an idea or a word of caution, I'd love to hear from you.