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Which RAID to go with?

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July 11, 2009 10:41:47 PM

Hey guys! So I've finally replaced my ten year-old system with some money I'd been saving up for a while. I found an awesome deal on WD Caviar Black 1 TB HDD (32 MB cache I think) at a local electronics outlet. $65 a pop. I had some money left over and got 3. Anyways, I'm having a headache deciding what RAID to go with. I go to university (CS major) and work co-op (CS) the rest of the 4 months. I've had HDDs crap out on me in the past to disastrous consequenses. So redundancy is a must. I like gaming, fiction writing, and movie-editing as well. Here's my dilemma:

- I need redudancy.
- I'd like speed.

Am I right that these are my options?

1. RAID 5. Redundancy. Faster read times, slower write times. Chews up the CPU when writing for parity. Some people hate it with a passion, like these guys: http://www.baarf.com/ (though I don't understand why).

2. RAID 1 the first 2 drives and keep the third for less vital files.

3. RAID 0 the first 2 drives and manually transfer vital files to the third drive. Con is that I'll probably forget to do this occasionally, and may lose older files I didn't deem important but now sorely miss (Oh, how I lament you my lost custom Warcraft III maps I designed in elementary school) for nostaligic or other reasons.

4. RAID 0 all of them and transfer files to my external HDD. Big files will likely put me off from transferring. Same cons as 3.

Most of my questions are about RAID 5 and 0.

1. Are the performance gains from RAID 5 and 0 noticeable? Do they affect things like frame rates and pop-in, or just loading-times (which aren't a big bother to me) and boot times?

2. Does RAID 5 chew up noticeable CPU speed (I have an i7 920)? Will that affect games? Do most games do a lot of writing to the HDD (I'd assume not)?

3. Are RAID 5 write times sluggishly slow (say half as fast), or only like usually 10% slower?

Thanks. At this time I can't afford another HDD. I'm saving up for and waiting for SDDs to get cheaper so I can load my OS onto one. Oh, and the controller I'd be using is the one built into the p6t deluxe mobo.

On an unrelated note, if anyone wants to field or knows, is the built-in sound in the p6t pretty good? Good directionality? Can't seem to find anyone to answer that one.

More about : raid

a b G Storage
July 11, 2009 11:22:24 PM

Best (and simplest) option, run each disk separately.
Keep the OS and data on one drive and an up to date copy of your important data on the other drives.

Software RAID is a PITA.
When you have an issue with it, and you probably will, odds are you will lose all data from the raided drives.
When you can afford it, a SSD will be faster in most cases than your raided 1Tb Hd's.
If your motherboard ever fails or needs to be upgraded, you are sol migrating the raid array and will lose your data.
It will also be impossible to save your data from a RAID 0 array if one of your drives fail.
Much safer is to manually backup your data to the spare drives.

Any potential speed increases or supposed reliability bonuses are completely offset by the potential issues with software RAID.
IF you must RAID, get a dedicated PCIe RAID controller.
July 12, 2009 1:33:45 AM

I don't understand what you mean by SATA harddrives? My drives are SATA. I didn't realize there were so many potential problems with RAID. Even if I set it up through my P6T's BIOS? Do HDDs do little in terms of performance, both in gaming and video editing (exluding load times of course which they do have a bearing on)?

That's the drive:
http://www.wdc.com/en/products/products.asp?driveid=488
Related resources
a b G Storage
July 12, 2009 1:46:58 AM

Drrrrr, I meant to say SSD (Solid State Drive) :pt1cable: 

Yeah, even set through the BIOS it is still software RAID.
For data security you either need a hardware RAID card or to just manually back it up.

With the three drives, I would set it up something like this.
One drive as the boot drive, keep all your software and not to important data here.
Another drive as attached storage and the last drive in an external enclosure used for backing up your data with.

In this way you will give yourself a few layers of protection.
If your OS tanks and you have to reinstall, your data will be safe on both the internal storage drive and the external storage drive.
If both internal drives tank (virus, lightning strike, cheap PSU, etc) your data will still be protected on the external backup (assuming you only turn it on to backup/restore your data).
For really important data, burn some DVD's off and put them in a protected binder.

My 0.02$ on data security.
July 12, 2009 2:54:50 AM

Thanks for the advice on security. Makes sense when you phrase it like that. Although, I might give away the 3rd drive to a family member or something since I don't need that much data storage and already have an external HDD. What's your opinion of HDD performance for home computer use? Is it usually afterthought next to things like CPUs and GPUs? Only affects things like load times in games and video-editing apps?
a b G Storage
July 12, 2009 3:01:57 AM

Yeah, a faster Hd is nice but secondary to the other components.
Mainly, a faster hard drive will load windows, games and applications a bit faster.
If you get past the slightly longer wait, you will still have the same experience.
a c 415 G Storage
July 12, 2009 3:07:47 AM

I can't speak as to the robustness of the motherboard-based RAID solutions. I still consider them "hardware raid" as opposed to RAID performed at the OS level, but I think they're less fully featured than a dedicated RAID controller card. Or maybe I'm wrong - when you use these motherboard RAID implementations is the work REALLY done at the OS device driver level? If someone can tell me I'd be very interested to know. I'm planning a RAID 1 implementation for Win7 testing and if the work is really done at the OS level then I'm going to reconsider.

For redundancy and best performance, go with RAID 1.

Only use RAID 0 if you need the extra space and are willing to accept double the risk of data loss (you loose your data if either drive fails, and with two drives you chances of failure are doubled).

Only use RAID 5 if you need the extra space. It won't be TWICE as slow for writes, perhaps in the 1/4 to 1/3 slower range, depending on what you're doing. It may not be too bad for an OS disk if you move the pagefile, user directories and temporary directories to another disk.

In terms of performance in use, what you'll notice is anything that does a lot of disk access. For games, as long as you have sufficient RAM, that will primarily be boot and load times.

Remember that RAID is not backup - it's primary purposes are to improve performance and eliminate downtime. There are a ton of reasons why you can loose your data even with RAID. A good backup strategy includes offline copies of your data both on- and offsite.
July 12, 2009 4:25:20 AM

On the P6T RAID is built into the BIOS. You can start up the machine without the OS and setup RAID. On the other hand, the P6T also comes integrated with osme LInux-based OS I haven't looked at yet; apparently it's limited to features like Skyoe and browsing. I haven't booted it up yet. So I don't know if you would consider that HW RAID or SW RAID.
a c 415 G Storage
July 12, 2009 6:41:00 AM

blind_synergy said:
On the P6T RAID is built into the BIOS. You can start up the machine without the OS and setup RAID. ... So I don't know if you would consider that HW RAID or SW RAID.

Well I know that it's the ICH10R chipset itself that implements the RAID - I wouldn't call that the BIOS, I'd call it hardware.

On the other hand, Windows does require the ICH10R RAID drivers (and not just the standard AHCI drivers) if you enable RAID on the motherboard. Now with most RAID implementations this is true so that you can use software that monitors the status of the RAID sets (failed drives, rebuild status, etc.)

The ICH10R documentation itself describes support for RAID 0, RAID 1, RAID 5, etc., so I'm assuming there probably isn't any significant work done at OS driver level apart from monitoring and configuration.

But there's this lingering suspicion in my mind - I just wouldn't put it past them to push a lot of functionality up into the software just like some of those infamous "Windows Printers".

It would be nice to hear from someone with the inside scoop...
July 12, 2009 7:12:28 AM

The option you have not considered and is the most secure and cost effective of all...back up important files to Dvd. That way when you have massive failure on all your drives you still have a safe copy stored away. You can get a spindle of 100 dvds for about $30, so its cost effective, also. Most backup software will write to Dvd drive also, so you can schedule automatic backups of new files or do it manually. Cheap and effective solution for redundancy.
a c 357 G Storage
July 13, 2009 8:48:59 PM

RAID built into a mobo's chipset is still software RAID. It is NOT part of the OS; its code is in the MOBO's BIOS chips designed for the board's main chipset. It is NOT hardware RAID because it does not have dedicated hard drive controllers, and it does use the CPU to do a bunch of the work in conjunction with the controllers built into the mobo chipset.

Migrating disks written with one RAID controller to another has been a real crapshoot that often failed in the past, because the various makers do not have agreed standards. One solution is to use only dedicated RAID controller boards in a PCI slot; then you are putting your faith in being able to buy in future a second RAID board from the same manufacturer which still can deal with those hard drives exactly as the original controller board did. Another option is to use the software RAID included with recent Windows; then your faith is in Microsoft's maintaining backward compatibility from one Windows to another.

A third option I have experienced is using a mobo with an nVidia chipset that includes RAID built in. Their website specifically claims that they use the same RAID algorithms for all their built-in RAID systems so that any current system can handle properly any disks written and managed by a previous nVidia RAID system. I had to test this recently. I had a system with an ABIT mobo with nVidia chipset, running a pair of drives in a RAID1 array. System failed (looks like leaky bad capacitors in the voltage regulator section of the mobo), so I searched out a new board with the featrures I need, including an nVidia chipset with RAID0 and 1 built in. Bought a Gigabyte board. Swapped board, hooked up the old drive pair, set the RAID options in the BIOS, and booted first time cleanly right from that drive pair! Amazingly smooth. That worked perfectly. I don't know how many other chipset makers guarantee that same performance.
August 17, 2009 7:41:10 AM

sminlal said:


For redundancy and best performance, go with RAID 1.



Not true regarding performance of RAID1. That is covered on basic RAID education 101 that can be found on any RAID info website.
a b G Storage
August 17, 2009 11:00:49 AM

The problem with RAID5 is how the controller handles the array. To achieve a decent (trustworthy) reliability with Windows that's only possible with a relatively expensive true hardware RAID controller, which defeats the purpose of RAID5 for cost-efficient redundant storage in the first place. To get good write performance out of RAID5 write-back caching is required. If there's no battery (battery is only available to hardware RAID controllers) or UPS to keep data in cache alive during a power-cut then the chance of unrecoverable data loss is high.

Pure software RAID5 (or ZFS & RAID-Z) with Linux/BSD on the other hand can be as reliable, fast with the added bonus of flexibly than hardware RAID. The downside is no more Windows hence they're mostly used in dedicated NAS box.

I've ran a 3x1TB RAID5 array on Intel Matrix RAID (which is host/driver RAID btw) for around 5months before moving onto hardware RAID. Had no problems, but I knew if I needed to move the array onto another motherboard without Intel Matrix RAID support then I'd be SOL.
Luckily PCIe 8port SATA/SAS RAID card can be had for around $100 now 2nd hand.

Quote:
- I need redudancy.
- I'd like speed.

4disk RAID 1+0 sounds like the solution for you since you can get 1TB Caviar Black at only $65. Buy additional for backup.
a c 415 G Storage
August 17, 2009 6:39:50 PM

Paperdoc said:
RAID built into a mobo's chipset is still software RAID. It is NOT part of the OS; its code is in the MOBO's BIOS chips designed for the board's main chipset.
Actually to be clear, the BIOS contains software that allows you to edit and store configuration information - but the actual work is done by chipset drivers that are loaded into the OS at boot time.
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