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First Home Build - 3 drives RAID?

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July 11, 2009 12:08:59 AM

I just received all of my hardware today for my first custom system (27, so been a long time coming).


Pre question specs:

1x - Seagate Barracuda 1TB Sata 3G drive
2x - Seagate Barracuda 500GB Sata 3G drive

MB - Biostar Tforce TP45D2-A7

Question: How should I setup the 3 drives raid wise for best performance and organization, or just ignore RAID setup completely? Do I need to purchase a hardware controller separately for this home system?

Further info: I'm not sure if/how I should go about considering using RAID for my system. This box is our main system in the home aside from 2 laptops and the xbox 360. I DO NOT currently have a backup solution in place so keep this in mind if preservation of data is something to consider.

Thank you in advance for any suggestions

More about : home build drives raid

a c 361 G Storage
July 13, 2009 7:04:18 PM

RAID is of little value to most home users. (watches over shoulder for incoming flames)

RAID0 can increase data transfer speeds to and from the hard drive system, but only a little bit, and mostly for a long sequential data file, read or write. Because it splits the data over two drives and alternates between them it can reduce the time "lost" in disk head seek operations. However, most hard drives sold now are quite fast and the gain from RAID0 is small. On the other hand, again because your data is split over two drives, you cannot tolerate any drive failure. In a RAID0 array, a total failure of one drive means you have lost ALL of your data and it cannot be recovered. So the risk of total loss of data is twice as bad as the risk for one drive, although current drives are pretty reliable. In such a system, frequent reliable backups are even more necessary than for other systems! RAID0 makes all of your disk space available - 2 x 500 GB drives in a RAID0 array gives you one 1000 GB drive.

RAID1, on the other hand, constantly keeps a mirror image of all your data on a hidden second disk. (Well, actually, it uses both disks behind the scenes, but you only are aware that there is one disk.) The downside is that you have to buy and install two disks to get the use of one. For example, putting both your 500 GB Barracudas into a RIAD1 array will give you one 500 GB drive. In the event of a total disk failure the RAID system will detect the problem, revert to using only the good drive, alert you to the problem, then assist in repairing or replacing the faulty drive to restore the whole array. This all seems so secure it can produce a false sense of calm. The problem is that any operation that looks "normal", like deleting the wrong file, or some virus attack on your data, will be done instantly on BOTH copies of the data - this system provides no protection against that type of trouble. So again, a RAID1 needs a good backup system in use, but some people forget that. RAID1 may speed up disk read operations very slightly, but hard to notice in real life.

With a minimum of 3 drives you can create a RAID5 array which has some protection against data corruption and loss, although not the same as RAID1. I saw a 5-disk RAID5 array fail so completely (with simultaneous problems on two of its 5 drives) that it had to be restored from backups after the disk problems were fixed. This was in a professional setting where duplicate really good backups were maintained, so the restoration process was possible, even though time-consuming.

Most built-in RAID systems are software-based, so you are using processor time to run them. Thus, they slow down your system slightly, offsetting some or all of the advantages of reduced head seek time delays.

RAID1, RAID5, and higher levels are used in professional server situations where central file servers require complete reliability and the ability to recover from disk failure while still in full operation. A home user almost never needs that. RAID0 may offer some small but real speed advantage but it carries higher risk of complete data loss than just about any other disk system, so it is a favorite of gamers and speed junkies who are willing to deal with that loss. Again, not usually suited for the home user.

I'd suggest you consider three possibilities. One is to forget RAID altogether and set up your system with three individual drives. The second is to use the two 500 GB units in a RAID1 array that you boot from and use as the C: drive with mirrored backup. Then you install the 1TB drive and partition it to a data drive of about 400 GB and a backup data drive of about 600 GB. Then you FAITHFULLY do backups of both your RAID1 array and your data partition to the second partition. This still is not really good - your'e backing up some of your data to the same drive, just a different partition, and it's all in the same machine. The third option, for extra speed but with more risk, is to set up the two smaller drives on a RAID0 array of 1 TB, then use the other larger drive as a 1TB backup system. Again, not totally ideal since you're all in one machine.

My own main machine has two 320 GB drives in it. Then I have a 500 GB drive mounted in an external case which usually is turned off and not connected. From time to time (not as often as I should) I clone my C: drive to the external in one partition, then clone the D: drive to a second Partition on that external, then shut it down and disconnect. Completely separate drive not normally connected (so isolated from power surges). Flaws: don't do backups frequently enough, and do not take the backup drive off site.

In the retail sore my wife operates, the Point of Sale computer really only runs the POS software and has no connection to the internet. I have its two drives in a RAID1 array for mirroring. I bought WinZip Pro and set it up to make a .zip file backup of all the POS software's data files each evening at 11:50 p.m., saving it to the same RAID1 array. Now, that's not really good - if a drive fails, the backups are on the same drive! But since it's mirroring, we could recover from most single-drive failures. And since I have a daily backup, if a file gets corrupted today on both halves of the array, I have a valid backup up to the end of yesterday. At each month end I copy the last days' complete backup off onto a USB drive and then copy it to my main home machine, so I have monthly off-site backups. Certainly not enough for a major enterprise server system, but should be good enough for this application.

A general rule for backups: TEST THEM! Too may people make backups and never verify that they can restore from them completely. A failure at that stage when you've already lost "everything" can really make a lousy day so much worse. I saw one of those incidents once many years ago, and they were lucky. A bright young system programmer reasoned out many possible reasons why the backup tapes could not be read (assuming they simply had data written to them in an unanticipated format) and the first remedy he tried worked! The residual shock came in recognizing that, with many professional computer sites using this operating system and its backup tools, none had ever reported that the backups were un-readable!
a c 415 G Storage
July 13, 2009 7:22:03 PM

the_folder said:
I just received all of my hardware today for my first custom system (27, so been a long time coming).


Pre question specs:

1x - Seagate Barracuda 1TB Sata 3G drive
2x - Seagate Barracuda 500GB Sata 3G drive

MB - Biostar Tforce TP45D2-A7

Question: How should I setup the 3 drives raid wise for best performance and organization, or just ignore RAID setup completely? Do I need to purchase a hardware controller separately for this home system?

Further info: I'm not sure if/how I should go about considering using RAID for my system. This box is our main system in the home aside from 2 laptops and the xbox 360. I DO NOT currently have a backup solution in place so keep this in mind if preservation of data is something to consider.

Thank you in advance for any suggestions

You have to understand what your priorities are:
- performance
- reliability
- capacity

Use RAID 0 if you DON'T need reliability and you want best performance or capacity
Use RAID 1 if you need reliability and somewhat better performance
Use RAID 5 if you DON'T need performance and want reliability and capacity

If I had your configuration I'd use RAID-1 on the two 500GB drives and put the OS on them, then use the 1TB drive for data. That's because I value reliability foremost.

You should see some performance improvement in boot and load times with RAID. Despite what Paperdoc said, the CPU time needed to handle RAID is negligible compared to the time the CPU spends waiting for the disk. During booting, logging on and starting up your programs the system accesses a LOT of individual small files, and being able to issue I/O operations to more than one disk in parallel will speed things up.

Once everything's loaded, any performance increase depends entirely upon what you're doing. If you have a disk-intensive program then you could see a performance improvement. But (once they've been loaded) the programs most typical users run would probably benefit more from additional RAM than from a faster disk.
July 13, 2009 8:20:24 PM

Thank you very much on both replies, it answer all my small questions and even the main focus of this system. I know I will go with the 2 500GB drives being in raid as the OS/program volume now and use the 1TB drive as my data.

as cheap as these are I think my best plan should be to buy another drive and keep it external for backups only somewhat like your setup with only connecting it for backups (which will take personal reminders and time to keep track of doing it).

Again much appreciated and informative.
!