RAID 1 reliability question

[piano632]

I'm thinking about getting an inexpensive RAID enclosure such as this one:

http://www.mwave.com/mwave/skusearch.hmx?SCriteria=AA74430&CartID=done&nextloc=

While RAID 1 seems nice and easy, my only concern with RAID 1 is if the original disc gets corrupted in some way, wouldn't it copy this corruption to the mirror drive? Would it be safer to have 2 independent drives and use a software program to verify that the 2 drives have identical data (though more time-consuming, of course)?

I'm just looking for input from people who've used RAID 1 on it's long-term reliability and whether or not you've had any corruptions, since I can't really afford to lose any data I put on there.

[jagabo]

While RAID 1 seems nice and easy, my only concern with RAID 1 is if the original disc gets corrupted in some way, wouldn't it copy this corruption to the mirror drive?

It depends on where the problem occurs. If one drive develops bad blocks or fails the second drive has all your information intact. But if the O/S decides to splatter junk all over the drive both will be corrupted. And if you accidentally delete files they will be deleted from both drives. RAID 1 is not a replacement for backups.

[Nelson37]

Yes, corruptions occur. Yes, they are often copied to both drives.

But what really, really bites the big one is that IF that controller fails, you got a big lump of NOTHING. And you can rejoice in the fact that you spent extra money for the worthless pile of unusable data.

The idea behind RAID 1 is to bring downtime to a minimum. When it works, it can be a good thing to have. BUT, when that controller goes, God help you.

In my professional ipinion, RAID is more trouble than it is worth.

Seperate, STANDARD drives on STANDARD controllers gives you redundancy and reliability. Drive fails, the other is OK. Controller fails, it can be easily replaced.

I like Synchback for maintainig backups, very fast after the initial copy.

[jagabo]

The idea behind RAID 1 is to bring downtime to a minimum. When it works, it can be a good thing to have. BUT, when that controller goes, God help you.

For those who don't know, the theory is that you can pull a bad drive and replace it without shutting down the system. The remaining drive gets copied to the new drive in the background while the system is still live.

In my professional ipinion, RAID is more trouble than it is worth.

Seperate, STANDARD drives on STANDARD controllers gives you redundancy and reliability. Drive fails, the other is OK. Controller fails, it can be easily replaced.

I agree. I often use a simple

xcopy /e /d /y /c source destination

[piano632]

Exactly what I was afraid of. I think I might still buy the dual bay enclosure mentioned above but use it in "normal" mode (2 separate drive letters). Now I have another question I'm unclear about:

I am using a eSATA PCI controller card (the Rosewill RC-210 which has a SiI 3512 chipset, to be exact). The enclosure docs say that accessing 2 drives through a single eSATA port requires a controller with "port multiplier" capability. I am correct in understanding that any card with a Silicon Image chipset has port multiplier ability?

[redwudz]

That's a SATA 150 two channel card. That's all that's available, and one's internal. You need a different card if you want more than the two channels. I use several of the PROMISE SATA300 TX4 PCI SATA II 4-Port Adapters: http://www.newegg.com/Product/Product.aspx?Item=N82E16816102065 I use a PCI slot adapter for the external sockets.

I don't think that card, or most others I am aware of, have 'port multiplier' capability.

[piano632]

I don't need any more ports. What I'm trying to do is be able to access 2 hard drives in a single enclosure through 1 eSATA cable connection (the enclosure only has 1 eSATA port but has 2 drives). The enclosure docs say you need "port multiplier" on your SATA controller or you will only "see" 1 drive in the enclosure.

What's confusing me is this at cooldrives which says controllers with Silicon Image chipset have "port multiplier":

http://www.cooldrives.com/saiipomu55hd.html

[redwudz]

AFAIK, a port multiplier is a hardware device. http://www.cooldrives.com/cosapomubrso.html I don't think a SATA adapter like you list would have it. If so, it would have a lot more connectors. But if someone has more information, it would be welcome.

[piano632]

I would imagine that the external enclosure has the actual hardware port multiplier built in, but the controller card needs to be compatible with it. Listen to the video near the end where the guy says most Silicon Image cards are port multiplier compatible (at least the RAID ones are).

http://www.cooldrives.com/saiipomu55hd.html

[INFRATOM]

Raid for mirroring is protection against if one hard drive crashes has no other use. if one hard drive crash you connect another one and do the setup. if controller fails you can connect one of the hard drives as a single IDE drive. The danger is with Raid 0 which combines 2 HD as a single which if fails you're left with your backup if you have any. You can combine mirroring too. If safety together with down time is your problem you have to go with Raid 5, that uses 3 or more drive and one drive is not counted towards the capacity it just keeps the parity info. Most motherboards come with Raid controller, setting up Raid is a bit tricky because it needs drivers that windows may not have. In that case streamline a windows disc with your Raid drivers.