![[H]ard|Forum](/styles/hardforum/xenforo/logo_dark.png){kind=logo}
Fake onboard raid or W7 Raid!?
- Thread starter Tazman2
- Start date
drescherjm
[H]F Junkie
- Joined
- Nov 19, 2008
- Messages
- 14,933
The Intel P67 raid is better than the W7 raid.
I wouldn't call the onboard RAID "fake" RAID. That's not entirely true. It's RAID without XOR processing yes, but it does have hardware acceleration. It's not a total software RAID solution. I prefer having all my RAID settings configured in the BIOS as opposed to Windows but that's just me.
- Joined
- Dec 29, 2000
- Messages
- 2,498
It's been a while since I've dealt with Intel's chipset RAID. Which pieces are hardware accelerated?
drescherjm
[H]F Junkie
- Joined
- Nov 19, 2008
- Messages
- 14,933
I believe raid1 is accelerated. But basically its fakeraid for raid5 since it has no hw xor engine and no dedicated battery backed cache.
- Joined
- May 7, 2007
- Messages
- 13,443
Actually this is exactly what FakeRAID is. All it is is a HDD controller with firmware that makes the OS see the drives as a single container and is controlled through drivers.
It is still CPU-based just like software RAID is, only the controller manages the disks rather than the OS.
Both have advantages and disadvantages, but both are of similar performance depending on the OS used.
FakeRAID is not hardware RAID though and does not have any hardware acceleration as it is purely processed through the CPU rather than the controller.
drescherjm, you might be right about this, though I'm not sure it is hardware acceleration.
software RAID1 yields no benefits of read/write speeds. FakeRAID RAID1 yields increased read speeds though as it will allow both disks to be read separately. I don't think this is a hardware acceleration function as much as it is the way the drives can operate independently when used on the controller.
Last edited:
Actually, I dislike the term fake RAID. It's bullshit. RAID is being implemented correctly, but it uses firmware and some features via that firmware and manages the disks in an option ROM just like a real controller. The processing involved in various RAID levels is done via software via the OS and the controllers drivers, but it isn't fake so much as it is a hybrid hard/soft solution. The overhead of RAID isn't mitigated by a XOR processor, but it's not a pure software RAID either. But none of them qualify as "fake" if you think about it.
Using the OS's RAID features will give you the ability to move the array to another PC if your PC fails or becomes inoperable. It's less of an issue with RAID1 because you can usually break the mirror and still use one of the drives by itself as a normal drive. However, in other RAID levels, the layout and metadata can be proprietary to the controller. If the controller (or motherboard) dies then you need that same model (or chipset) to access your data again..
Riley
Riley
- Joined
- May 7, 2007
- Messages
- 13,443
haha, I don't blame you for not liking the name, but afaik, it is the true technical term for it since the controller "tricks" the OS into seeing the drives as a single container. From the OS's standpoint, it sees a single drive, hence the FakeRAID name. From the user's standpoint, there are multiple drives in a real RAID configuration, so I definitely see where the dislike of the name comes from.
You are right, it really is a software/hardware hybrid. "SardwareRAID"
You can do that with the chipset controllers in many cases as well. Intel's RAID will import RAID arrays from other controller types much of the time. Most boards also have some kind of Marvell controller for their secondary RAID controllers. Now you can not go from the AMD chipset RAID to other controllers in my experience. Your right about RAID 1 though. If the Intel and Marvell controllers weren't so popular I'd be more inclined to agree. I prefer the simplicity of having the firmware manage the disks rather than doing it all through Windows or another OS. I've had more trouble with the latter than the former.
haha, I don't blame you for not liking the name, but afaik, it is the true technical term for it since the controller "tricks" the OS into seeing the drives as a single container. From the OS's standpoint, it sees a single drive, hence the FakeRAID name. From the user's standpoint, there are multiple drives in a real RAID configuration, so I definitely see where the dislike of the name comes from.
You are right, it really is a software/hardware hybrid. "SardwareRAID"
Hardware acceleration isn't really the right term either in thinking back on it. "Hybrid" is more accurate or "hardware managed" is too. Though I have to say I rather like "SardwareRAID."
- Joined
- May 7, 2007
- Messages
- 13,443
This is one of the advantages to software RAID that I really like and have used quite a few times.
Dan's post is spot on with FakeRAID. As long as the same/similar controller is used, the drives can be transferred fairly easily.
Old Hippie
Supreme [H]ardness
- Joined
- Oct 31, 2005
- Messages
- 6,013
I'm just wanting to bookmark this discussion.
The software/fake RAID differences have always been fuzzy in my mind.
HW and SW RAID was always easily differentiated by a seperate processor doing all the RAID computations but it's gotten a little confusing after that.
I appreciate the expertise being shown in this discussion.
The software/fake RAID differences have always been fuzzy in my mind.
HW and SW RAID was always easily differentiated by a seperate processor doing all the RAID computations but it's gotten a little confusing after that.
I appreciate the expertise being shown in this discussion.
- Joined
- May 7, 2007
- Messages
- 13,443
Yeah, it's definitely good to know that you have options when it comes to RAID!
- Joined
- Sep 27, 2005
- Messages
- 3,126
Aside from the IOP/dedicated memory/hardware aspect, I generally separate them out by how the linux kernel sees them. Your options are basically:
Kernel RAID: OS sees multiple drives and the logical drive is managed by mdadm or a similar tool
Fake RAID: OS sees multiple drives and the dmraid may be capable of assembling the logical drive
Hardware RAID: OS sees a logical drive with a proper driver
With Windows, fakeraid all a bunch of smoke and mirrors driver trickery, IMO.
Kernel RAID: OS sees multiple drives and the logical drive is managed by mdadm or a similar tool
Fake RAID: OS sees multiple drives and the dmraid may be capable of assembling the logical drive
Hardware RAID: OS sees a logical drive with a proper driver
With Windows, fakeraid all a bunch of smoke and mirrors driver trickery, IMO.
How is that smoke and mirrors? The chipset controller / firmware is doing the same thing as hardware RAID controllers do. It's doing the same thing you'd have to do with whatever software you'd have to use to manage the disks? How is that smoke and mirrors or any less proper than letting the software manage it?
It isn't as if they aren't getting the features they are paying for. People are generally well aware that the onboard audio isn't a true hardware solution in most cases, so why should we treat the drive controller any differently? In this world, buyer beware. It's their fault if they don't know what it is they are buying.
- Joined
- May 7, 2007
- Messages
- 13,443
your "kernel RAID" is in fact software RAID, use the official term.
FakeRAID is not smoke and mirrors, it is advertised as onboard RAID (it never says hardware RAID) and is a huge advantage to using Windows and RAID1.
There is nothing wrong with FakeRAID aside from the name.
btw, your last sentence just screams Linux fanboi.
- Joined
- Sep 27, 2005
- Messages
- 3,126
My reasoning is that the controller exports the physical drives to the OS and then it is the responsibility of a software layer inside the OS to assemble the array. Hardware controllers export the logical volumes (arrays themselves) to the OS and it is the responsibility of the OS to simply have the proper driver to "see" the arrays. This is why unix-ish operating systems see all the physical devices rather than the actual logical volume without the added assistance of dmraid (the software layer I mentioned earlier).
Proper software RAID removes any controller specific ties and, therefore, is portable to any system that has said software RAID support and is also capable of seeing the set of drives (the particular controller is irrelevant).
The smoke and mirrors is the portion between when the controller exports the drives to the OS and then the software layer installed on the OS assembles them as a singe logical drive, thus, in Windows, appearing to be a hardware RAID to the end user.
your "kernel RAID" is in fact software RAID, use the official term.
I used "kernel RAID" solely to differentiate from fakeraid as many people use software/fake/kernel RAID all interchangeably.
btw, your last sentence just screams Linux fanboi.
The reality is that Windows is an exception in how this is handled. Windows doesn't see anything if you don't provide the fakeraid driver. Every other OS is just going to see the individual drives which is normal. Fanboi? Not quite, but my job is probably 75%+ linux-related 9am-6pm Mon-Fri.
I can argue that it is the controller's responsibility to create the logical volumes and present a single unified volume to the operating system. It's simply a matter of preference as to which one you prefer. I can also argue that controller replacement isn't a big deal. I work in IT and have for many years. I've physically done it, and I work with this stuff everyday. I've seen more data loss from people trusting Linux's software RAID than to hybrid or true hardware RAID solutions. (And on that note, I've rarely seen data loss result from anything array related beyond drive deaths which isn't specific to software or hardware RAID, but rather both.) And more than that, many different controllers can import different / foreign arrays without difficulty. And in an IT environment getting controllers, motherboards, back planes etc. isn't that big of a deal. You either have everything under warranty or you don't. You either backup your data or you don't.
And your software RAID in Linux isn't portable to Windows. So it's portability is suspect as well or at least, has caveats of it's own just like any other solution does. I can also argue that due to the proliferation of Windows in the market, it's way is the normal way and Linux and every other OS does it backwards. You see how perspective works?
The point is, having your drives managed in firmware, be it a real hardware controller or a hybrid solution like that in a chipset isn't less proper or is it smoke and mirrors. The only people misled by hardware vs. software RAID solutions are the uninformed. They can form any number of conclusions based on either slight shreds of evidence, text they've glanced over, crap they've heard from other uninformed people, etc. "FakeRAID" as you call it isn't some immoral thing that the customer needs to be aware of and shy away from in favor of some "softRAID" solution. If someone concludes incorrectly that hybrid RAID is some how hardware RAID then we'll straighten them out and educate them as we always do. For those who do not wish to learn, there isn't anything you can do for them until that changes. It's hardly your problem or some evil plot by motherboard manufacturers.
- Joined
- Sep 27, 2005
- Messages
- 3,126
Of course perspective is relative. I work in the servers as appliances (for lack of easier way to describe it) market which is largely unix based. Windows is more popular on the desktop and IT side, agreed.
Side note: market share is almost always slanted since it's usually represented based on units sold and/or revenue, but that's another separate discussion.
I'm hardly on a crusade to inform the public of the dangerous dragon known as fakeraid, Dan, nor am I promoting linux (or Windows for that matter) software RAID. I simply stated, to the best of my knowledge, how the variants function.
Personally, I think you're getting all defensive over a coined term for motherboard RAID.
- Joined
- Dec 29, 2000
- Messages
- 2,498
Why do you suppose that is? I'd be interested in hearing more about this. How did they lose data in a Linux software RAID? Was it mdadm raid or LVM striping? Which RAID level was it?
On the face of it, it sounds really incredible, like if someone had said "I've seen more data loss from people using GNU Tar than from ARCServe," which may not be a false statement. If that person making the statement is a RedHat support tech, then that could be perfectly plausible and valid. Or if that person is an MCSE in a mixed environment and has poor Linux/Unix skills, then it's reasonable to assume that their hands have wrecked more Linux software arrays than hardware arrays. I'm really interested in hearing the extraneous details there.
Last edited:
- Joined
- May 7, 2007
- Messages
- 13,443
I have to agree with you, I've yet to see a failed software RAID using MDADM that has failed due to the OS and not the hardware.
FakeRAID on the other hand, I've seen plenty of controllers die and kill the array many times.
Like I said before, each has their strengths and weaknesses and it really depends on what you are using it or which OS you are using it with.
- Joined
- May 7, 2007
- Messages
- 13,443
I get that the drives can't be transfered to windows, that is one of the limitations of MDADM software RAID, but it can be transfered to other Unix-like OS's such as OS X and other Linux distros. This is one of the reasons I prefer software RAID to FakeRAID, but FakeRAID still has some advantages.
I get that you use Linux a lot, but don't dis Windows-based systems as FakeRAID has a lot to offer for most non-advanced users who don't want to go through the trouble of setting up software RAID, whether it be through Windows or Linux.
There is no smoke and mirrors, it is what it is. The firmware just makes the OS see a single array container which is how the driver and FakeRAID works. If you need to see the physical volumes and have a deeper management level with them without having to leave the OS, then use software RAID.
One isn't necessarily better than the other since they both use the CPU for all processing. I'll say it again, both have their strengths and weaknesses. You stating that one is better than the other kind of makes you sound like a fanboi, whether you are or aren't, and personally I don't care either way.
Also, software RAID is software RAID, not "kernel RAID". I've never heard anyone anywhere outside of your post use this term. Also, FakeRAID != software RAID, they are two very different animals.
Windows may not see the FakeRAID drive array without the driver, but without drivers, windows doesn't see anything, it's just the way Windows works. If you don't like it, don't use it.
Many businesses use Windows, not Linux. As much as I like Linux, I have to accept that they do not, and therefore I need to use FakeRAID. Most businesses can't afford hardware RAID controllers, but still want redundancy and the insurance of RAID. With Windows, I can easily setup FakeRAID on the motherboard within seconds, and it gives them what they want at a low to no-cost price. I would only use windows software RAID in a pinch if the mobo was old and did not support FakeRAID.
Essentially, you want FakeRAID to be something it's not, and in turn insult it and Windows. The majority of people in the world do not use Linux distros, they use Windows. If you don't like how it works, then don't use it, period.
fyi, under FakeRAID, RAID1 is a hell of a lot faster than under software RAID due to increased read speeds.
- Joined
- Dec 29, 2000
- Messages
- 2,498
fyi, under FakeRAID, RAID1 is a hell of a lot faster than under software RAID due to increased read speeds.
They both use the CPU there don't they? How is one faster than the other, and by how much?
I was under the impression that mdadm has really good mirror member read balancing at this point.
- Joined
- May 7, 2007
- Messages
- 13,443
Under FakeRAID, the disks operate independently due to the controller. Even though in RAID1 all drives will write as a single drive, the read speed is increased by about however many drives are within the array.
Software RAID, since it is managed by the OS and not through the controller (firmware), makes the disks read and write at the same time.
RAID 1 works great under MDADM and there is nothing wrong with it, there is just no read performance increase, at least from what I've seen. The read is the same as having one disk under software RAID and it even states this on Apple's site (OS X uses software RAID as well).