RAID and leftover space?

[giantbucket]

I have two hard drives - a 500G and a 750G. If I partition the 750 into a 500+250 setup then I can do a RAID0 using the 500G parts. But can I access the 250G slice as a simple non-RAID drive or does it get "lost"?

The RAID part is where I would store my Steam games.

 

[JackNaylorPE]

It's lost ..... But what do you hope to accomplish ? If you want high benchmarks, then you will accomplish your goal, but if looking for real world improvements in desktop applications (outside of specialized application like large databases, video editing, etc) and gaming, it just ain't gonna happen. we use AutoCAD and saw no noticeable improvement doing RAID 0 on SSDs

Here's a old THG post on RAID from some years back ..... I'd guess about half the links have expired.

http://en.wikipedia.org/wiki/RAID_0#RAID_0

RAID 0 is useful for setups such as large read-only NFS servers where mounting many disks is time-consuming or impossible and redundancy is irrelevant.

RAID 0 is also used in some gaming systems where performance is desired and data integrity is not very important. However, real-world tests with games have shown that RAID-0 performance gains are minimal, although some desktop applications will benefit.[1][2]

http://www.anandtech.com/printarticle.aspx?i=2101
"We were hoping to see some sort of performance increase in the game loading tests, but the RAID array didn't give us that. While the scores put the RAID-0 array slightly slower than the single drive Raptor II, you should also remember that these scores are timed by hand and thus, we're dealing within normal variations in the "benchmark".

Our Unreal Tournament 2004 test uses the full version of the game and leaves all settings on defaults. After launching the game, we select Instant Action from the menu, choose Assault mode and select the Robot Factory level. The stop watch timer is started right after the Play button is clicked, and stopped when the loading screen disappears. The test is repeated three times with the final score reported being an average of the three. In order to avoid the effects of caching, we reboot between runs. All times are reported in seconds; lower scores, obviously, being better. In Unreal Tournament, we're left with exactly no performance improvement, thanks to RAID-0

If you haven't gotten the hint by now, we'll spell it out for you: there is no place, and no need for a RAID-0 array on a desktop computer. The real world performance increases are negligible at best and the reduction in reliability, thanks to a halving of the mean time between failure, makes RAID-0 far from worth it on the desktop.

Bottom line: RAID-0 arrays will win you just about any benchmark, but they'll deliver virtually nothing more than that for real world desktop performance. That's just the cold hard truth."

http://www.techwarelabs.com/articles/hardware/raid-and-gaming/index_6.shtml
".....we did not see an increase in FPS through its use. Load times for levels and games was significantly reduced utilizing the Raid controller and array. As we stated we do not expect that the majority of gamers are willing to purchase greater than 4 drives and a controller for this kind of setup. While onboard Raid is an option available to many users you should be aware that using onboard Raid will mean the consumption of CPU time for this task and thus a reduction in performance that may actually lead to worse FPS. An add-on controller will always be the best option until they integrate discreet Raid controllers with their own memory into consumer level motherboards."

http://www.hardforum.com/showthread.php?t=1001325
"However, many have tried to justify/overlook those shortcomings by simply saying "It's faster." Anyone who does this is wrong, wasting their money, and buying into hype. Nothing more."

http://jeff-sue.suite101.com/how-raid-storage-improves-performance-a101975
"The real-world performance benefits possible in a single-user PC situation is not a given for most people, because the benefits rely on multiple independent, simultaneous requests. One person running most desktop applications may not see a big payback in performance because they are not written to do asynchronous I/O to disks. Understanding this can help avoid disappointment."

http://www.scs-myung.com/v2/index. [...] om_content
"What about performance? This, we suspect, is the primary reason why so many users doggedly pursue the RAID 0 "holy grail." This inevitably leads to dissapointment by those that notice little or no performance gain.....As stated above, first person shooters rarely benefit from RAID 0.__ Frame rates will almost certainly not improve, as they are determined by your video card and processor above all else. In fact, theoretically your FPS frame rate may decrease, since many low-cost RAID controllers (anything made by Highpoint at the tiem of this writing, and most cards from Promise) implement RAID in software, so the process of splitting and combining data across your drives is done by your CPU, which could better be utilized by your game. That said, the CPU overhead of RAID0 is minimal on high-performance processors."

Even the HD manufacturers limit RAID's advantages to very specific applications and non of them involves gaming:

http://westerndigital.com/en/products/raid/http://westerndigital.com/en/products/raid/

 

[giantbucket]

my intent was to make use of both of my small hard drives and get a nice large fast combined drive size. they're hdd (wd black 2.5"), just to be clear. and i was going to have all of my steam games stored on there (currently have 415G of games, so can't justify an SSD large enough for that, esp since i already have hard drives big enough). benchmarks are kinda nice albeit academic - the real plus would have been quicker access to content.

losing that remaining 250G of space would suck, though, so maybe the whole affair is not worth doing.

not sure where the SSD part came from (well, OS will be on SSD but that's beside the point).

 

[JackNaylorPE]

The SSD part came from even using SSDs in RAID 0, there is no practical gain. There simply is no observable performance improvement in gaming with RAID 0 on HDs, SSHDs or SSD's.

If you haven't gotten the hint by now, we'll spell it out for you: there is no place, and no need for a RAID-0 array on a desktop computer. The real world performance increases are negligible at best and the reduction in reliability, thanks to a halving of the mean time between failure, makes RAID-0 far from worth it on the desktop.

Bottom line: RAID-0 arrays will win you just about any benchmark, but they'll deliver virtually nothing more than that for real world desktop performance. That's just the cold hard truth."

However, many have tried to justify/overlook those shortcomings [of RAID 0] by simply saying "It's faster." Anyone who does this is wrong, wasting their money, and buying into hype. Nothing more."

"What about performance? This, we suspect, is the primary reason why so many users doggedly pursue the RAID 0 "holy grail." This inevitably leads to dissapointment by those that notice little or no performance gain.....As stated above, first person shooters rarely benefit from RAID 0.

Now if you do a 4 HD RAID array, you'd reach a point where the impact would be observable.

Those old 2.5" WD Blacks .... are we talking about a laptop here ? Recognize that older 500 and 750 GB models pale in speed with today's offerings. If on a budget, best storage improvement you could make for your games would be an SSHD. With separate SSDs and HDs, your problem is what to put where. With an SSHD, you put your 415 GB of games on it. Start playing Far Cry 3 and your FC3 files will all be moved in the background tot he SSD portion of the drive where they will remain until the firmware recognizes that you have stopped playing FC3 and have moved on to FC4. After you have loaded FC4 a few times, the FC4 files will have completely replaced the FC3 files on the SSD portion of the drive..... all of the benefits of the SSD w/o the hassle of moving things back and forth.

 

[giantbucket]

it's actually an ITX build, but i used laptop drives (they're no more than 2 years old) since they're small enough that i can stuff them just about anywhere inside the case.

i'll take a look at SSHD, but i'm not sure if my use would be predictable enough for the controller to. from what i gather, it takes several cycles for it to recognize my usage pattern, which i probably won't give it a chance to fairly do.