Partial Raid0 Question

I read on the following page:
http://kmwoley.com/blog/?p=429

That

Since people here seem to know a lot about Raid arrays.

I would like to ask: I have a laptop with WDC5000BEVT HDD, if I buy another one, will I be able to RAID0 only 100GB from each drive (for my Windows partition)...is this called short stroking?

if yes, then secondly, will I be able to somehow retain the data without the use of any external media like DVD-R/Ext Hard drive?

I only want to set this portion in RAID0 because I think Windows will feel a lot snappy to me as well as all the softwares I'll install in that drive and there is going to be no data on the drive that I will regret losing if something happens to the array. I have seen someone's HDTune results of a RAID0 pair of the same drives here in some thread and its results impressed me.

thank you

btw, the article I've linked is about Windows 7 Software RAID

(Need to make the purchase soon, it's either a WDC5000BEVT or a WDC3200BEKT)

 

First, you can't do a software raid like you want on the boot/windows partition as far as I know.

Second, even if you could, why would you risk it and your data? Yes, the benchmarks show 'better', but in actual use the benefits are far from the theoretical numbers the benchmarks indicate.

How are you 'risking' your data? Because although it should work how you say, doesn't mean it will - especially when you have no backup of your data because you think its safe - thats when the 'impossible' will happen and you'll regret RAID0 for the rest of your life (or, at least in proportion to how much and how important the data was that you lost).

If you get the Scorpio Black (BEKT), I suggest you make it the boot drive and your current Scorpio Blue (BEVT) the data drive.

If you insist on setting up RAID0, then match the HD's you'll be using. Don't use one 5400 RPM and one running at 7200 RPM like you're suggesting above.

You may find the following information interesting:

See:
http://forum.notebookreview.com/showthread.php?p=5617217#post5617217


Also, look into post number 11 on that thread to see how a possible two HD setup might be configured.

Cheers!

 

thanks for replying

i'm not asking "if I could", I am asking is it possible?

secondly, I don't keep a backup anyway maybe I will...afterwards

thirdly, I wouldn't regret if the data on my windows partition vanished right now...that's just how i set my partitions up

The problem is I can't RAID0 without making a clone of this drive right now, mainly because of game backups...there is nothing significant in this drive at the moment, definitely nothing I won't be able to download

I'm not insisting, it's just that it's hard to resist...nwo I come to think about it, I've never kept a backup before either so what difference will it make

Ok so I figured out that I actually CAN backup almost all of my stuff that I want to retain minus Windows and other Programs...

Is it advisable to setup a RAID0 seeing that I never kept a backup before and don't plan on buying an external unless there's a good deal?

but my main question is...is the arrange I have mentioned, possible...from your answer it seems it's not

 

Sorry, my information says no, it is not possible - unless somebody can come in with new/better info for you.

Good luck.

 

It's an interesting article, but the ICH5R is a pretty old chipset (2003), and thus I question his results compared to a more modern chipset like an ICH9R, considering he's using a 6 year later software implementation (Windows 7 - 2009).

His point about unmatched disks is a reference to the size of the disk, (like putting a 500 GB HDD in RAID with a 250 GB HDD) and not so much the speed. I'm not sure exactly how RAID will handle 2 mismatched drive speeds; my guess is it'll essentially run as if it was 2 HDDs of the lower speed, but this probably depend on the algorithms implemented, and that depends on how the RAID controller is setup.

Yes, you can RAID0 only 100 GB from each drive using a software RAID implementation, if you parition the drives with 100 GB each accordingly. I don't know if this is called "short stroking".

No, if there's a data failure in the RAID0 partition (depending on the actual failure), it will be unrecoverable without backup.

 

Wow. thanks for that explanation

I just ordered the drive, can you also link me to a guide that'll help me?

Now the only part that is left unanswered is:

1.Would I be able to save my data before RAID0-ing 100GB from each drive?
2.If said RAID0 partition is going to be a windows partition, would I be able to make a clone img of the current partition, store it in my other partition and restore upon successfully arraying the 100GBs in RAID0?

Thank you

 

I'm afraid I can't help you with a guide; all my systems to date have been single HDD models, so I've never had a use for RAID yet.

1) Certainly, as long as you have somewhere to save said data. Setting up RAID wipes all data that was on the partition/disk that you're setting up to be in the RAID array, so any data there that you want to keep you'll need to pull off and copy somewhere else beforehand.

2) Assuming you have enough room, I would think so. Although, if you have enough room, I'd probably just partition off the free space first into the 100 GB, set that (new) partition to RAID, and then clone over the existing (old) partition to the new RAID partition, which saves you a copy back/forth step (compared to make new partition, clone current to new partition, set old partition to RAID, copy back).

Oh, I should also probably note: I don't think you can use software RAID as an OS boot drive, so if you're going to use software RAID, I don't think you can put your OS in the (software) RAID array.

 

oh...then defeats most of the purpose i guess, well i have bought the drive...when afterwards i buy an external, then i'll set all of it to be in RAID0

thanks for the help, will experiment with the new drive

 

Yeah, software RAID0 as a boot drive runs into a chicken and the egg scenario; you can't read from a RAID0 volume unless the OS is already loaded so the software can handle reading from the striping, but you obviously can't load the OS from the RAID0 volume without something that can read the striping first, so...

This is where the firmware implementation comes into play, since it can handle reading the RAID0 until the OS is loaded, at which point it can hand it off to the OS. Or a full-up hardware RAID chip, obviously, can do the same thing.

Just remember that if you set all of it to be in RAID0, you will not be able to read any of the disks at all unless they're all hooked up, because your data will be broken up into chunks and spread out over all of the disks. This is really why RAID0 is so dangerous; while you get the benefits of faster access time because you can access multiple disks simultaneously, if any one of those disks has a serious failure, you lose everything.

 

yea...i understand
life is full of compromise isn't it lol

well hopefully, by the time i start earning (about 3 to 4 years forward), 500GB SSDs will be under $100 so I can definitely wait 3 years for a 250MB/s transfer speed hehe

by the way, how would a person attach them as externals to another pc? isn't possible right?

 

Attach them to another PC? eSata (best) or USB (slowest).

Cheers!

 

i meant the RAID0 hard drives, not SSDs...sorry for confusion

 

If you mean attaching a RAID array to another PC, if it's software RAID, and the other PC is running the same OS, it's at least theoretically possible. The issue at that point would be the ports on the computer; there's generally little point in connecting a RAID array through USB, since USB would prove to be a huge bottleneck to the access speeds, and few notebooks have more than one eSATA port. Remember, the issue with RAID is that you (usually) need to connect more than one HDD at the same time, so you have to be able to hook up the entire array to the PC that's trying to read them.

 

Wait!

If I'm understanding you correctly, then unless the other PC was running the same hardware/software with respect to the RAID0 setup you had on the original PC, then you probably will never see that data again.

If you further mean actually booting up from that RAID0 setup; as far as I know, impossible - unless you are moving from identical hardware to identical hardware.

Cheers!

 

Tilleroftheearth: We're talking about a pure software RAID here, where the RAID is handled completely by the OS, and the only hardware involved are the HDDs themselves (well, and the CPU time the OS needs to calculate the RAID array algorithms). For a setup like this (which cannot be a boot drive due to the fact that the OS needs to be loaded before the RAID drives can be read, thus resulting in the chicken and egg situation I mentioned earlier), moving the array to another computer that runs the same OS _should_ work, since, again, everything is handled through the OS, and thus the same OS should be able to "pickup where the other one left off", so to speak.

In the more common firmware RAID setup (this would be pretty much all the notebooks and computers that advertise that their HDDs can be put in RAID, since an OS implementation by its nature can be done on pretty much anything that will accept more than one HDD, due to the lack of a need for any extra hardware), you would need the identical hardware, especially for booting. On the flip side, you can actually boot from a firmware (or full hardware) enabled RAID, as the firmware/hardware will handle reading the RAID volume for the initial startup (and afterwards in the case of a full hardware controller; firmware chips typically hand off the RAID work to drivers that run off the main CPU after bootup, which is another reason it's commonly called "Fake-RAID").

Edit - well, technically, if the RAID array was a RAID1 array as opposed to a RAID0 array, you might be able to boot from it, as you should be able to read from a RAID1 array with few problems because it's not striped; however, if the "main" HDD (the one used for bootup) goes bad, oftentimes the boot is unable to properly swap to the mirror to boot from it.

 

There is no such thing as a pure software RAID.

The kind of RAID we're talking about here needs Intel Hardware and Intel Software including a compatible MS O/S.

I may be wrong on any specific configuration - but I'd rather error on the side of caution, than give false hopes to the OP that 'he'd be able to pick up (on a new system) where he left off (on the original, or old system).

The HD's are just 'dumb' devices like you mention. But that doesn't mean the systems they're connecting to are 'smart' enough to know these drives are in a RAID0 configuration.

RAID1 is a waste of HD's and gives a false sense of security. But, what it does offer is the ability to use one drive or the other to get data off of it successfully (again, because the system they're plugged into does not know if it was in a RAID1 array or not).

Cheers!

 

there is actually...and it doesn't even require that you get a RAID controller...it's been there since Windows 2000

anyways...I have bought the hard drive and I will take caution if and when I enable RAID0

 

You're missing the point: 'since Windows 2000' is a requirement, just as I stated for one of the 'ingredients' for 'software raid'.

It also depends on the drivers and chipset you have (and what system you try to put it into 'next').

Good luck.

 

Actually, MAC OS X, FreeBSD, Linux, NetBSD, OpenBSD, OpenSolaris, and Solaris 10 all also support software RAID (of their own, mind, so you can't mix and match), so I don't think Intel software is necessarily an issue.

And since we're talking about RAID implemented through the OS, the system doesn't have to know that the drives are in a RAID configuration: the OS does. This is why I said that as long as the OS is the same, it should work.

See, Tiller, what we're talking about here is not firmware RAID or hardware RAID, where there's a chip that presents the drives to the OS as a single logical unit, but software, where the drives are presented to the OS as separate units, and the OS itself "joins" the drives together into a single dynamic disk. At this point, there's probably a saved data file/style of some sort on the HDD that will tell the OS that this drive is in RAID with another drive, similar to how the old pkzip (ok, really dating myself here) would handle a zip file spanned over several floppies. Anyway, given that, the same OS, even if in a different computer, should be able to reconstruct the RAID array, much as the same installation of pkzip on another computer could reconstruct the spanned zip file.

If it helps, Tiller, try looking at the Wikipedia page on RAID - it has a section on the various sorts of RAID, including software, firmware, and hardware.

http://en.wikipedia.org/wiki/RAID

 

Judicator,

Lets just simply agree that we are saying the same thing in essence, but the distinctions I point out are not as important to you as they are to me. I am fairly experienced with RAID - both software and hardware based.

I have never found wikipedia to be a source of information, but thanks for the link.

All my experience points to is that if there really was a thing as 'true' software RAID, I would not be so quick to shy away from it - almost as much as I shy away from hardware RAID, btw.

Oh yeah, pkzip... ahh! the good old days.

Cheers!

 

well, i have the other hdd now
but ofcourse, windows didn't boot up when i set bios to RAID

and since there are no RAID options enabled in Disk Management...i think i'm ok with 2 separate drives