RAID 1 Questions

[RITE1]

I plan to use a RAID 1 setup on a computer and have a few questions.

First, how picky are raid cards? For example, I believe I have an ATA 133 drive (new Dell Dimension 4600), would a SATA raid card be backwards compatible? Can I use one drive that’s ATA 100 and one that’s 133?

http://www.newegg.com/app/ViewProdu...=11&manufactory=1119&DEPA=1&sortby=14&order=1

Promise FastTrak S150 TX4 PCI Serial ATA Raid Controller Card - RETAIL - $90
vs.
Promise FastTrak TX4000 PCI ATA/133 Raid Controller Card - OEM - $105

The SATA version of the same card $15 cheaper??

Frankly, I don't know which of these cards to get and what the particular differences are. What accounts for the doubling of price from the cheapest promise raid card (around $50) to the $100 card? The specs look very similar, not that I know what many of them mean. I just need a simple, reliable RAID 1 card.

Any advice? Thanks

Rick

 

[fatmander]

It is best to use identical drives, Raid, Cheap and quick fix are 3 things that do not work together very well.
It is best if the drives all run at same speeds

A SATA hard drive uses a SATA cable(SATA new standard for older IDE Devices), some of the SATA raid cards support both SATA and IDE Devices. This one doesn't

Both these Cards support a PCI-X(66MHz) slot, which is twice as fast as a normal PCI(33MHz) slot (has a extra inch long slot at back of the card)
PCI-x is backwards compatible ith PCI, but..
If your PC doesn't support PCI-X, you can end up creating a bottleneck in the south bridge(not that there isn't one already there), RAID, 1GB LAN, firewire and USB2 could 'in theory' try and push 2146MB/sec down a 133MHz bus.

Latest Intel boards have removed the gigabit Lan off the southbridge altoghether, so it is worth considering this if you are looking at building a busy server.
hth

 

[RITE1]

So;

I have two 80 gig ATA133 hard drives and I want to set them up in a raid 1 configuration.

From the link above I would need a PROMISE FASTTRAK TX2000?

Also, if I wanted to do a raid 5 setup, would I need three 80 gig drives or two 80 and one 160?

Thanks for any help!!

 

[olderthandirt]

RAID-1 is a set of mirrored drives. Usually and most suitably matched drives. RAID-5 is and array where redundancy is by exclusive or "x-or". This allows each drive in the array to contain data which is stripped and has parity,i.e. faster and redundant data storage.

RAID-1 requires 50% overhead, in short two drives each containing the data. RAID-5's overhead is based on the number of drives. Three is the minimum requirement.

3 drives 33.3% overhead
4 drives 25% overhead
5 drives 20% overhead

and so on. Easy way to remember - all drives should be equal in capacity. you lose one drive per RAID-5 array.

if 3 drives of 80 GB your storage capacity is 160 GB.
if 4 drives of 80 GB your storage capacity is 240 GB.
if 5 drives of 80 GB your storage capacity is 320 GB.

If you are doing this in a server running Windows 2000 or 2003 you can use the software to setup the raid. This is slower than hardware but it works. Hardware setups you need to check with the factories.

Promise, Ashton Peripherals and 3-ware are all good IDE vendors. For SCSI's Adaptec, and others work.

I suggest you read this article.

http://www.uni-mainz.de/~neuffer/scsi/what_is_raid.html

 

[RITE1]

Good read.

I’m still confused - If I have two 80 gig drives in a raid 5 that are striping for a total of 160 gigs, with only 80 gigs left, where does a mirror exist?

 

[reneleb]

With two drives you can only use RAID 0 or RAID 1. You'll need at least three drives to use RAID 5.

 

[Matheny]

]pc3]

Raid is somewhat confusing. This site,

http://www.robustdigitalsolutions.com/html/raid-5.html,

has Raid-5 illustrated so that one can see where the "mirror" resides. The mirror resides in segments across all drives, with enough redundancy to reconstruct all data in the event one of the drives fails. That's why at least three drives are required for Raid-5, and accounts for the loss of storage.

 

[RITE1]

I was bsin with one of my friends and had it explained to me - I apreciate your reponces though!