Are there any RAID system to avoid at all cost?

[Armornone]

Are there any RAID system which should be avoided or do they all pretty much do the same thing if you want to keep your data in a relatively safe raid 5 configuration?

Thanks.

 

[thiggins]

RAID is not a substitute for backup. Be sure you have a backup of any data that you don't want to lose and make sure you put your NAS on a UPS.

 

[Armornone]

RAID is not a substitute for backup. Be sure you have a backup of any data that you don't want to lose and make sure you put your NAS on a UPS.

I realize nothing is 100% safe but I was wondering if there was 1 system that you would recommend stay away from.

Maybe because of noise issues, vibration,sloppy configuration, limitations or if they all pretty much all meet a basic acceptable level of operation.

Thanks

 

[claykin]

Well, a hardware RAID controller will generally be more reliable and perform better than a software type controller (such as the Intel chipset controller, Silicon Image, etc..)

Thats not to say that the software controllers are unreliable, but the reality is anything you can do in hardware will generally work more reliably than a software solution.

Examples of hardware RAID controllers are the Dell Perc series, LSI MegaRAID, etc..

Unless you absolutely need a larger volume that RAID 5 can provide, I recommend a RAID 1 solution over RAID 5. You stand a better chance with RAID 1 from a recovery standpoint if it ever came down to it.

And as Tim advised, RAID is not backup. RAID is designed to improve system uptime not to circumvent backup. Don't be fooled.

 

[Armornone]

Are all raid devices software raid in a sense? Just dedicated equipment vs shared equipment?

In other words, I understand that some RAID is done with hard drives just plugged into a motherboard and running software on your computer.

Is hardware raid basically software running on a dedicated card device instead of running on the general operating system ?

With those cards, do you basically just need the drivers for the computer and that is it or do you nee something like freenas ?

Thanks for your help.

 

[memilanuk]

That's an interesting question...

I remember a number of years ago when I was just starting to fool around with Linux, and there were some lower-end consumer IDE RAID cards around (by Promise, if memory serves) that disappointed a lot of people because they bought them thinking that since they were a separate, dedicated card that it must really be hardware RAID. For whatever reason, it wasn't - they were still some sort of software RAID. I don't remember if they had drivers in the OS, or what, but they weren't the same as the dedicated, high dollar hardware RAID cards. The same thing seems to be the case today - even on motherboards that have 'onboard' RAID built into the BIOS... from what I've heard, to operating systems like Linux or the various flavors of BSD, the drives still appear as regular individual hard drives, not as an array.

Why exactly that is, that the OS sees something despite what the motherboard and BIOS in between the CPU and the drives must be trying to tell it... is way beyond my level of understanding at this point. Where does it go from being 'soft' RAID on a chip to 'hardware' RAID... on a chip?

Any takers?

Monte

 

[HDClown]

Why exactly that is, that the OS sees something despite what the motherboard and BIOS in between the CPU and the drives must be trying to tell it... is way beyond my level of understanding at this point. Where does it go from being 'soft' RAID on a chip to 'hardware' RAID... on a chip?

Any takers?

Monte

When the RAID controller has it's own processor. Onboard RAID and those cheap RAID cards do not have a processor. They have a BIOS and SATA/SAS controller to manage the array, but all RAID calculations are handled by your systems processor.

Software RAID is done purely at the OS level, there is no RAID controller BIOS to manage the array. There really is no CPU impact to "manage" the array, it's all in the actual calculations going on in the array, so there isn't any performance benefit to having one of those cheap RAID controller cards, or using onboard RAID, vs. purely in software. There are other trade-offs however, but that's another discussion.

 

[Armornone]

Raid Card recovery

If you use a RAID card like LSI megaraid, 3ware, etc.. and your operating system( lets say Windows XP) get corrupted or fails.

Are you able to just reinstall the operating system and drivers and gain access to your data via the raid ?

Or does an operating system error compromise the safety of the data on the Array ?

Does it matter if you have software RAID or hardware RAID ?

Thanks.

 

[HDClown]

When you use a true hardware RAID card, the entire RAID subsystem (controller and drives) is self-contained to those drives and controller.

If the OS is not on the RAID subsystem, or on a dedicated partition on the RAID subsystem, and the OS corrupts to the point that you need to reload, or the OS drive fails, you can just reload the OS and access your RAID array like nothing happened.

If the OS is on the RAID array, and sharing the same partition as your other data, and the OS corrupts to the point that it needs to be reloaded, you would need to put the drives and card in another computer and boot it up so that you could access your data.

I'm not overly familiar with software RAID in failure of OS scenarios, but it's a lot trickier of a situation to deal with because the OS itself is managing the RAID entirely.