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4 hard drives, just a bit of help please

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  • Hard Drives
  • NAS / RAID
  • Storage
Last response: in Storage
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August 18, 2006 4:32:34 PM

I just purchased a new computer and my question is this(yes i have read and searched, but im not understanding the information).

Is it possible for me to use 3 wd 250gb hds in a raid 0 with the 4th doing automatic mirring of the data?

edit: Should i just put all of them into a raid 5 configuration? While i do not understand some of the terms here, for reliability reasons more than one of the 4 would have to fail. But does this cause a hit in performance(not failing drive, raid 5 overall).

From what i can tell i would need a 5th hard drive to make it raid 0+1.

From a reliability standpoint im not awfully concerned as i can burn everything to several dvd's, but would like the 4th drive grabbing the data from the other three and making an auto backup.

Thanks.

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August 18, 2006 6:37:25 PM

4 x 250GB drives gives you the following choices:

RAID 0: No redundancy -- lose 1 drive, you lose all data. Very fast reads and writes. 1000 GB total drive space.

RAID 0+1: Fully redundant, protects against any single drive failure. Very fast reads & writes, though not quite as fast as the 4-drive RAID 0, but you may not notice any difference if the RAID 0 speed is limited by other factors, like the PCI bus speed or south bridge speed. 500 GB total drive space.

RAID 5: Fully redundant, protects against any single drive failure. Fast reads, possibly close to the RAID 0 in speed, depending on what controller you're using. Reasonably fast writes, but writes will be slower than reads. 750 GB total drive space.

RAID 5 is probably your best option with 4 drives. Cost may vary -- depends on if your motherboard can do RAID 5 by itself or if you will need to purchase a controller card. Different controller cards perform differently, of course. Check Tom's for recent reviews of RAID 5 controllers.

Standard RAID disclaimer: RAID 0 offers no redundancy at all -- lose one drive, you lose all data. All other RAID levels are redundant and protect from a single drive failure, but only a hardware failure of a drive. RAID does not protect against OS corruption, file system corruption, viruses, spyware, accidental deletion of files or partitions, or formatting. RAID is not a substitute for a backup of critical data.
August 18, 2006 7:07:13 PM

SomeJoe has got it nailed. You could also consider a Raid 0+1 or a 1+0, but Raid 5 is probably a better option, depending on what your looking for...
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August 18, 2006 7:10:37 PM

i agree, but for raid 5 unless it's 100% hardware i would use either raid 1 or 0+1 since software raid 5 is crappy.
August 18, 2006 7:56:29 PM

I think SomeJoe's post should become a sticky topic.

software RAID 5 ain't as bad as it used to be. It's actually starting to approach some HW RAID5 implementations. Not that I'd recommend using it still.
August 18, 2006 8:05:35 PM

there's no replacement for a hardware chip that can process XOR parity calculation.
August 18, 2006 8:10:08 PM

Yeah I would go with Raid 5. You'll probably want a raid controller though, seeing as software raid is crap, and most onboard raid controllers aren't very good at raid 5. Another thing you could do if you wanted all 1000gb of storage, is set up a JBOD array. You get all your space on one theoretical drive like raid 0, but it's only as fast as one drive. On the other hand, if you lose one drive, you don't lose everything, unline RAID 0.
August 18, 2006 8:32:21 PM

I would go with the RAID 5 if you can. I personally have a 0+1 array consisting of 4x250 in my server because I don't have the proper hardware. I don't really need that much speed though; it's just hosting a bunch of software images for installation purposes, as well as personal web site development and development databases.

Still, I dream of buying an Areca controller and about 8 750GB hard drives. :wink:
August 18, 2006 9:03:45 PM

Edit: Ok i see now, wasnt grasping very well. raid 5 750gb total storage= 3 drives in raid 0, 1 doing mirroring.

Thanks for your help. I left my post below to see if you had any other inputs on the setup.

The hardware I purchased is listed below. The mother board supports 0/0+1/5/jbod.

If you use raid 5, can i use 3 of the drives in the 0 configuration with the 4th in mirroring? I want to make sure i have this nailed down before they get here.

1 ASUS A8N32-SLI Deluxe Socket 939 NVIDIA nForce SPP 100 ATX AMD Motherboard
PATA 2 x ATA100 up to 4 Devices
SATA 3Gb/s 4
SATA RAID NV RAID 0/1/0+1/5 JBOD
Additional RAID Controller Sil 3132

1 ASUS EN7950GX2/2PHT/1G Geforce 7950GX2 1GB GDDR3 PCI Express x16 Dual GPU Video Card
1 FSP Group (Fortron Source) FX700-GLN ATX12V/ EPS12V 700W
1 AMD Athlon 64 X2 4800+ Toledo 2000MHz HT Socket 939 Dual Core Processor Model ADA4800CDBOX
2 OCZ 2GB (2 x 1GB) 184-Pin DDR SDRAM DDR 400 (PC 3200) Unbuffered Dual Channel Kit System Memory Model OCZP4002GK
4 Western Digital Caviar SE16 WD2500KS 250GB 7200 RPM SATA 3.0Gb/s Hard Drive
1 ViewSonic VA1912wb Black 19" 8ms Widescreen LCD Monitor -
1 Pioneer 16X DVD±R DVD Burner With 5X DVD-RAM Read Black
1 Creative Sound Blaster X-Fi XtremeMusic 7.1 Channels PCI
1 Microsoft Windows XP Professional With SP2B 1 Pack - OEM
4 EVERCOOL EC-MC-OR Aluminium Golden Memory Heatsink -
August 18, 2006 9:55:01 PM

Quote:
Edit: Ok i see now, wasnt grasping very well. raid 5 750gb total storage= 3 drives in raid 0, 1 doing mirroring.

...

If you use raid 5, can i use 3 of the drives in the 0 configuration with the 4th in mirroring? I want to make sure i have this nailed down before they get here.


Well, that's the concept, but that's not what it's really doing. It's not a combination of RAID 0 striping and RAID 1 mirroring -- don't think of it that way.

The real techy details of the way RAID 5 works is not necessary to understand, but think of it like this:

Your data is striped across all 4 drives, kinda like a RAID 0, but for every 3 blocks of your data, the controller writes a 4th block of extra info. That's why your capacity is 3/4 of the raw space on the drives (raw space = 1000 GB, available space = 3/4 of that, 750 GB). The 4th, extra blocks, are distributed across all the drives in a pattern.

The extra info is such that if any one drive fails, the controller can reconstruct what was on that drive by using the data and the extra info that is on the other 3 good drives.
August 19, 2006 12:52:59 PM

I think ill go with raid 5 as you all suggest. For the most part the system is used for gaming, some work and storage of photos of the family.


Next question i have, has anyone ever had a drive go bad in a raid 5 configuration? How did your control tell you something was wrong? and how did you and how long did you take to repair it.
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