Help with RAID 1 and wdidle3

[DennisMenace]

I'm about to setup a new RAID 1 array (I hope) with two old WD greens (WD15EADS-22P8B0), but I need some help/advice as I'm new to RAID. I'm not booting from the drives/array, I intend to just use them for important backups.

Firstly, should I use firmware or software RAID?
I'm going for security not performance (hence RAID 1 ), but I assume they are both "secure" in the sense that if 1 disk fails/corrupts then I can still rescue ALL my data from the remaining drive. If that's the case, what are the differences in speed, reliability and system overheads?
Firmware - Mobo is a Z68-UD3H which supports RAID 0/1/5 - but AHCI or RAID? (See next question...)
Software - Should I use Intel RST or Win7 (Disk Manager)?

Secondly, as I boot from an SSD, SATA Mode is set to AHCI, not RAID. Do I need to change this to run the RAID array? Will this impact SSD speeds?

Finally, should I be worried about load/unload cycles?
One drive is at ~100k, the other nearer 200k, neither has wdidle3 "installed" to lengthen the spindown time (although I'm not 100% certain of this, one drive might have been "wdidle3-ed"). Does this matter? Will it affect RAID performance? (I assume this has to be set before I build the array).

Thanks in advance for your help.

 

[wonko]

I suppose someone has to say "raid is not a backup" first

RAID1 should protect against a single drive failure, but that's about it. If you inadvertently overwrite files, or the file system gets corrupted, or you get a virus/trojan, or you have a lightning strike or PSU fault (etc.) then RAID won't help. So I wouldn't bother unless you've already got a backup strategy which reflects the importance of the data.

Re the green drives, I don't bother with WDIDLE3 unless the LCC is ramping up at an alarming rate, which is really a function of how frequently the drive is accessed and I can't see why RAID would affect this. You might have difficulty reading the SMART data from the drives once they are RAIDed though. Also, you might want to bear in mind that the green drives aren't really designed for RAID (TLER) so may tend to drop out of the array.

Hope this helps with some of the questions

 

[DennisMenace]

I suppose someone has to say "raid is not a backup" first

RAID1 should protect against a single drive failure, but that's about it.

Understood, but it's better than losing a drive that's not in RAID1. I'll also be backing-up to external (USB) HDDs.

Also, you might want to bear in mind that the green drives aren't really designed for RAID (TLER) so may tend to drop out of the array.

That was my main concern, hence the worries about wdidle3 (not for the longevity of the drives, but for stability of the array). Sadly these are the only suitable paired drives I own.


My main concern is firmware vs software RAID, and how that could impact the SSD (currently set to AHCI). I'm guessing firmware is better as it uses the Z68 chipset, where the SATA controllers are - can anyone shed more light on this?