Raid 5 Data Recovery

[bryante]

I am planning a high-end home file server in which I will implement a Raid-5 Array. I am trying to figure out which is the most reliable option:

1. Motherboard Raid-5 capability
2. Controller Card
3. Software

Much of the information I could locate on data recovery and Raid-5 involves the anticipated failure of a disk drive (this I understand). What I am concerned about, however, is the case of a controller card or motherboard failure in options 1 or 2. How easy is it to recover the data from a Raid-5 array in the case of a motherboard failure and/or controller card failure?

 

[TrojanWarBlade]

IMHO, software raid is the most reliable since you can find that hardware raid can loose driver support and stop you being able to upgrade your OS easily. It's not the fastest solution but with modern processors and motherboards, the speed difference is not really noticable.



Trojan.

 

[dbData]

RAID based on a controller card is the best. If you're concerned about the controll card failing, buy 2.


Rick

http://www.data-recovery-hub.com

 

[comtec17]

TrojanWarBlade, dude what have you been smoking?

Software based RAID is not only unreliable, it carries a ton of overhead via the OS taking up memory and CPU cycles.

Hardware based RAID is always the best choice due to the mear fact that if you lose your OS, your data is still in tact.

 

[TrojanWarBlade]

comtec17, have you actually ever used raid?
I have, and I've lost data as a direct consequence of a hardware controller no longer being supported. So don't tell me that you know better cos I've been there.
Have you actually performance tested hardware vs software? I doubt that very much by your comments.
Unreliable? I've used software raid for many years with no problems at all.
I think it's not me that's been smoking something.

In an ideal world, everyone would choose hardware raid but if you do, you just have to be careful that it's gonna be continually supported. If there is any doubt about that at any time, you need to get the data off the drives asap.

Trojan.

 

[comtec17]

I have directly managed very, very large amounts of disk for a bank as well as have been directly consulting with Storage for 6+ years now and know what I am speaking of.

If you are using a piece of hardware that loses support or end of lifes that soon then you are definetly purchasing the wrong hardware.

I have done thousands of performance tests on arrays larger than you could only dream of and of RAID sets that will make you drool.

Hardware based RAID is always the way to go unless you just cannot afford it due to you being a very small business with a very small budget.

 

[TrojanWarBlade]

Comtec, you know nothing about me and it appears you have had it easy.
Nobody CHOOSES to buy hardware that looses support but life can be a bitch like that sometimes. You are entitled to your opinion just as much as I am entitled to mine.
I take it you've never had software raid fail you?
No? Thought not.
I, on the other hand, HAVE had hardware raid fail me and cost me big time. There in lies the warning. If you're too arrogant to consider anyone else's opinions or experience worth listening to then you're gonna have some interesting problems to deal with in your life.
I wish you luck cos you're gonna need it.


Trojan.

 

[comtec17]

Sorry about getting off topic Bryante. Here is a whitepaper that will hopefully help you make your opinion.

http://graphics.adaptec.com/pdfs/raid_soft_v_hard.pdf

 

[wjlight]

Blessed be the pessimists for they hath made backups."

Don't rely on RAID alone. Regularly backup your data to tape or some other non-volatile medium you can physically store away from the computer.

 

[Rufusman]

Agree fully with wjlight. RAID is only good for hardware failures. It lulls people into a false sense of security where they think they are covered, then you get a software corruption.

Backup,backup and backup.

http://www.pcbsearch.com.au

 

[Tghare]

The discussion is pretty hot and additional information and comments may not help that but here goes.

SAS, SAN, NAS, whatever... I have been using internal and external RAID, with controllers in the server/external RAID arrays and software RAID, even tried SCSI bus arbitration in 1989, long before software RAID was even a thought. here are some facts and observations.

Drives will fail_._

Software RAID is inexpensive at time of purchase.
Hardware RAID has been and can be expensive but is now available inexpensivly as well.
Mirroring controllers are not as fast as true RAID, but they recover much easier for the new tech.

Hardware RAID is my personal favorite, ...expensive external array's with redundant controllers, hot sparing, alarms, fiber connections built in battery backup and large ammounts of RAM. My Elanor... But that is not a home system.

Software RAID is inexpensive if you have lots of CPU cycles to spin. Everything is a balancing act of anticipated performance needs/wants vs. cost - no matter what everyone else tells you, only buy what meets your needs. It is better to plan on replacing the device every few years since technology changes all the time.

As far as reliability;
Software RAID has failed without recovery on several of my customers systems - could be the software or could be my customers.

Hardware RAID has failed without recovery on several of my customers systems - with notable differences; an entire lot of drives failed within a few days, three failed before a tech made it onsite, they lost data; a manufacturer defect on a several RAID chassis.

If you have the need and can afford a SCSI or fiber channel RAID with a battery backed caching controller, go for it... the drives perform continious duty much longer than ATA (a device that has the controller on the drive), and they will likley be supported much longer than other spinning media formats since it is a commercial device.

Whatever you do, buy drives from different production lots to keep the manufacturing defects at bay.

Remember to always back up what you can't restore, the rest is faster to reload anyway.

Hope this helps.