Wow, the rhetoric from the product vendors really has you spun. It's not your fault tho - it's sometimes difficult to assess the facts and form an original opinion. I would be interested to know why you think RAID0 isn't actually RAID tho. LOL (Just because there's no actual redundancy? So we should call it "IAD0"
)
So let's break it down (again for like the billionth time). What benefit is RAID5 in a CONSUMER or SOHO environment? Remember I already said it was good for large system or data-center types. First we need to clarify that the only scenario that counts in a MacPro is single drive failure. If two drives fail on you in a MacPro environment you're a freak of nature and should apply to the Guinness book of world records. You also need RAID 6 to protect against a two drive failure - RAID5 can't do it!
So on to the breakdown:
RAID5 Needs above RAID0:
- Enterprise Class drives. (Many or most controllers will not allow desktop grade drives!)
- Two extra do nothing enterpri$e class drives. (one running in the RAID Group and one to replace whatever might break)
- A RAID Controller Card. (RAID5 is not natively supported in MacPro) - As a result your system heat and fan noise is increased too.
- Many controller cards are power hungry as well and about the equivalent of running an extra 75 to 100 watt bulb for every hour your machine is on. So this is about an extra $50 a month or $600 a year just to operate it. And if we look at the power per terabyte it's even worse. And on top of both those there's another 10 to 25 watts added for the extra do-nothing drive.
Well, this all looks very bad doesn't it? Golly, there must be something good about RAID5. If nothing else simply because so many people preach it's use - like you just did. So what are they?
Well sadly no, there are almost no advantages and the disadvantages far far outweigh any advantages that might exist - as I've just demonstrated above. The real advantages of RAID5 only come into play in data-center like environments. Those SE's have the right to hype RAID5. For them it saves them time - which is money, when they can maintain the data uptime and carry out the repair simply by replacing a hot-swapped drive while falling back only one
of several levels of redundancy.
Certainly that's the case then on MacPro too right? Nope, unfortunately not, without the multiple levels of redundancy it doesn't apply. And without one member of the singular RAID5 array, operation is too slow to actually continue working with it in most cases. You really need to insert that extra drive you had to purchase and allow it a few hours to rebuild. Now wait a minute, that's the SAME as RAID0_with_a_backup - can't really use the data till the array is restored. So gee-wizz, you were sacrificing 1/3 speed and spending
over twice as much for nearly no practical benefit at all? Well, the one other advantage that may exist is booting.
IF your controller card allows booting
and IF you installed your OS on the RAID for some reason (and not an SSD or SSHD)
then and only then you have the advantage of still being able to boot from the RAID5 array which wouldn't be possible with RAID0
if there was no RAID0 bootable backup. Wow, that single advantage is almost meaningless then? Indeed.
Yup, that's right. So here the RAID5 list sits with mostly disadvantages and almost no advantages at all. How about RAID0 compared to RAID5, How does that list out?
RAID0 advantages over RAID5?
- Is natively supported on MacPro (no need to shop for or purcha$e a RAID controller),
- Can use faster per $ Desktop grade drives,
- Can use larger Desktop grade drives,
- More speed per number of drives used - better benefit,
- Can configure 2-drive arrays (not possible in RAID5),
- Uses less power from the mains ($),
- Uses less power per terabyte (lower system heat and fan noise),
Wow that's great! But we've all read the scary rhetoric put out by vendors peddling RAID controllers... isn't there any truth to those? Well, no, not really. A simple Time-machine volume eliminates every single one of them. Well damn, then why do engineers say RAID5 is so great? They don't!!! Not for small systems like the MacPro and they haven't for the past 4 or 5 years - at lease not the ones who can add and subtract. What? What are you talking about, what's changed? Well, basically the very math which used to show some advantage to RAID5 has shown that there is none any longer - for small system implementation:
Sure, if you're running 3 or more individual arrays of 3 to 7 drives each then yes, RAID5 is a so-so good solution. RAID6 is much better however! But if you're running the 4 to 6 internal drives and maybe one other external array enclosure then RAID5 is really not for you. Both data integrity mathematically speaking, and as a matter of price|performance ratio RAID5 is inferior to RAID0.
EDIT:
On RAID1, this is really only useful if you are expecting a single drive to blow up. Maybe you have some ancient drive which you're replacing with an identical model. Set them up in a RAID1 array until the ancient one pops and then just throw it out (NOT! remaking the RAID1 array at all).
A backup like TimeMachine is superior in every way (when all things are considered) to any form of RAID redundancy. The only time RAID redundancy makes any sense at all on a MacPro like system is if you have repurposed it as a highly trafficked server system where the critical mission being sought is data availability. And then as mentioned, multiple levels of redundancy are what's needed. This is generally outside the interests of typical MacPro users/owners as they seem to profile here on MacRumors.
