Is Raid 5 possible on a an already setup Raid 0?

[sassan]

As I understand Raid 5 would be a mix between Raid 1 + Raid 0 , so I would have the backup capability with Raid 0 performance. I already have Raid 0 setup and I'm thinking of adding a 3rd hard drive for just in-case my hard drives die. Is this possible?

 

[gtvr]

Almost certainly it is not. RAID 5 is striping with parity, and the parity bit is distributed amongst the drives in the array. You should look at your documentation, but you probably have to recreate the array (which will destroy existing data).

 

[sminlal]

gtvr is probably right. In theory a RAID system could perform a conversion, but it would be a very difficult thing to do because in RAID-5 the parity blocks are actually distributed across ALL the disks, not just on the "last" one. So I'm pretty skeptical that any RAID controller would actually support a conversion.

 

[sassan]

Best answer selected by sassan.

 

[Super Dog Help Us]

I am a bit surprised by the replies. I am doing a conversion from Raid 0 to Raid 5 right now by using the Intel(R) Matrix Storage Console. The help manual assures me I can do this based on my particular I/O Controller.

So while there are limitations, the question is not whether it can be done, but rather whether it can be done on your particular system. You would be best served by determining if you have or can get the Intel(R) Matrix Storage Console or something similar and then following the Help and Contents guide.

By the way, while it is converting, I can still use my system which is a Windows 7 setup with a high level processor(s) and a high end Motherboard and my I/O Controller is of the ICH10 variety.

Good Luck.

 

[Super Dog Help Us]

Best answer selected by sassan.

nNote: I have a similar setup to "sassan". Asus P6T Deluxe V2, Core i7 920, 12g ram. Conversion is going smoothly but I had to reset the controls so it does not auto sleep if I am not interacting. The conversion takes several hours but I can continue to use my system.

 

[Super Dog Help Us]

OK. The conversion went smoothly. I even played Borderlands while it was underway with no drop in FPS or degradation of gameplay. Had I not known that I was doing a conversion, I would not have guessed a migration was underway. In fact it finished while I was playing and I couldn't tell.

Final Notes: I used the default setting of 64 for striping and my Raptor drives had about a third to a half of free space. With"Raid 0" I had a little under 300 GB total space (two 300 GB raptors). Now I have 558 GB usuable (three 300 GB raptor) with 351 GB free space. So I gained about 200 GB of free storage and recovery ability if a drive fails. I'll call this a "win" "win"!

 

[goobaah]

You can definately do this with MATRIX RAID as others have said. In fact you can reboot your system while you are doing this and it will start up again. It can go to sleep and it will also continue. Read/write times will be slower. Its a bit painful if your boot and app drive is doing the conversion. There are quite a few conversions available.

 

[Super Dog Help Us]

Thanks "goobaah". Apparently you really know your stuff. So much now is system specific.

Since we are getting into deeper waters, I did a little research (Wiki, Intel, Asus) into software, hardware, and firmware RAID. It's much more in depth than I cared to delve into, but being an old retired mainframe guy I just couldn't resist.

"sassan" has the Intel stuff since he has an Asus P6T board and I am thinking that it is a firmware type RAID since it is located on the southbridge. What great stuff. It decreases core processor overhead and bridges the gap between expensive hardware RAID and boot-disadvantaged software RAID by putting a chip on the motherboard. Kudos to Intel, Asus and the P6T family.

 

[gtvr]

I guess that's why I left myself an out with "you should look at your documentation"

Glad you could get it working.

 

[Super Dog Help Us]

So now I am a bit curious as to why the first two knowledgeable gentlemen leaned toward the "probably and almost certainly cannot" idea. I mean no disrespect whatsoever. And a little more depth might help future data truth seekers.

For example, is a hardware and software conversion more likely to be a "no-go", but a firmware conversion more of a "probably maybe"? Or is Matrix RAID its own little unique exception to the "no can do - maybe" logic. Perhaps the "hands-on-been-there-done-that" guys can add some clarity.

Btw, now I'm seriously thinking of converting from RAID 5 to 10. Lol. Either that or keep a raptor drive ready as a spare, since the controller can mark it as such.

 

[gtvr]

well, it was a generic question, without knowing the specific model of RAID. I've used enterprise RAID controllers that supported this (at least on paper) but never tried it - I'd describe myself as having a healthy paranoia about computer storage. With the systems I've supported, losing data could mean a high financial impact, so I try not to play "tricks" with storage, such as converting between RAID types. But obviously this system supported it, and it worked.

Sure you want to keep a raptor as a spare? That's a lot of performance sitting there doing nothing. You could send it to me & I'd put it to use. LOL.

 

[Super Dog Help Us]

Since you have thrown in some credentials I guess I should as well. I have been in mainframe data processing tech and ops since the 70’s for large and later very large corporations. I’ve tinkered with PC’s for the last 10 and built a high-end gamer last year. Here is what I know: drives fail, conversions sometimes fail.

For an individual, downtime is a frustration, for business, a substantial expense. But the old days of backups and downtime recovery have been augmented by real time redundancy, and nonstop error handling. And that is part of what RAID 5 offers.

RAID 0 means “zero” redundancy. When his hard drive fails, “sassan” will have to replace an old drive, rebuild his OS, and recover his data. And since the other drive is also old, guess what. That’s a lot of frown-time. If he converts to RAID 5 his system can continue to run and then rebuild itself with a replacement drive. When the next old drive fails, same thing.

So while conversions always carry some risk, (backup!) the probability of replacing a hard drive is an absolute. And as for keeping a spare raptor just lying around, it keeps my spare GTX 295 company. Lol.

My habit of tinkering tends to mean extras. ;-)

 

[Super Dog Help Us]

Wow! As it turns out my RAID 0 to RAID 5 conversion was timely. It has been two weeks since I converted and tonight port 0 failed.

My system locked up and when I rebooted my Intel(R) Matrix Storage Manager not only notified me of a failure, it showed me which drive along with it's port and S/N. Since I had purchased a spare drive all I had to do was power down, R&R, power up and then designate the new drive for the rebuild. The rebuild is slow but I can (and am) able to use my Gamer PC. And as "goobaah" pointed out, I can shut down and the process will resume when I come back up.

I have had several systems rebuilt due to failed drives. When a system fails neither me nor the "experts" immediately know what the problem is. Power supply? Memory? Mother Board? Processor? It takes a lot of time to troubleshoot. With RAID 5... very different story.

My previous downtime for a high-end tower PC: Several hrs on the phone with tech then 2 wks for warranty repairs then many hrs to rebuild system and recover data.

Downtime with RAID 5 on my personal build: 30 minutes.

 

[goobaah]

It is likely that the drive that flagged the error did not really fail or even throw a smart event. I have have been running 6 drives in raid 5 on the intel p55 for a few months now and I have had two occasions where something happened and my data needed to be re-verified. Not very inspiring, but everything worked and nothing was lost. There are issues with using normal HDD's and RAID that has something to do with TLER or whatever. You could be having that happen on occasion. I keep track of which port fails that way I know for sure that there really is something wrong with the drive. If I have the same port throw an error more than once, I start scratching my head and check SMART data. If you had an error in RAID 0 that was not the death of a drive, but just an alarm, the matrix manager would have told you there was something seriously wrong with your array, but it would have still worked as long as the drive was not dying/dead. Then you could just right click it as healthy and it would verify itself and life goes one.

In the pro world, I would hesitate to do a transition unless I had to. Its hard for me to imagine a case where I would need to extend my disk space by adding a drive at work. I could just create another share or add another block of space for a DB and allocate it to the tablespace that needs more disk, etc. But RAID 5 expansion is something that can be done, both in software and hardware. In the business world, if you value your data you will not rely on RAID, yes you will use it for increased availability, but the most important stuff is on tape and likely offsite. Point being, put things that you cannot afford to lose somewhere else besides that RAID if you can. I have an old IDE drive in a case in my closet. Probably not going to break just sitting there.

Good luck RAIDing,

Oh, another things, RAID 10 is nice because ... the data is slightly more protected, write speed is faster if that matters, and rebuild times are muuuuch faster. It just chews up drive space.


pleh, you're using raptors, not sure why it dropped unless it is really dead.

 

[Super Dog Help Us]

Again thanks for the detailed follow-up and advice. I have had some "re-verifies" and I suspect you are correct about a potential "false fail”. Similiar to antivirus "false positives", unwarranted problems can result and further research is prudent.

As for business practices I give both you and "gvtr" due credit for your cautions. My conversion was on a non-critical system and in business would be considered a 'test bed".

 

[Super Dog Help Us]

Ok, after another “false fail” and some more “reverify’s”, I decided there must be a better way. The IMSM won’t convert from RAID 5 to RAID 10: I would have to do a rebuild and I’m not in the mood. Internet advice on the “falsies” had conflicting advice so I went to my mobo’s support/forum specifically for guys with Raptor drives, RAID 5, similar Motherboards, etc.

The advice I followed was to download the Intel Rapid Storage Technology and “Presto Change O”, no more problems. It has not been very long since I installed Intel RST so I can’t “swear on a stack of Bibles”, but the difference so far is dramatic. Some have problems with IRST but most are voicing relief from the RAID 5 “bug-a-boos”.

One guy called Intel Rapid Storage Technology the “unofficial” replacement for Intel Matrix Storage Manager. Removal of IMSM was not necessary or recommended and it looks as though IRST just sub-tasked it. The interface is different and the IMSM panel appears to be gone.

So for those looking to quell Intel MSM RAID 5 quirks, take a look at the Intel Rapid Storage Technology add-on.

 

[Super Dog Help Us]

Ok, further investigation on Intel's site shows Intel Rapid Storage Technology as a name change and product evolution with different versions of the product being:

Intel® Application Accelerator RAID Edition
Intel® Application Accelerator 4.x
Intel® Matrix Storage Technology (or Intel® Matrix Storage Technology software)
Intel® Matrix Storage Manager

Wiki lists IRST as Intel's 2010 version of IMSM. So it looks like a combo of new version/name/update.

 

[Super Dog Help Us]

Well it's a little over a couple of months and still no problems with the IRST. Not even a hiccup. No more false alarms. It just sits quietly in the background and does it's job.

Too bad the Best Answer on this site is a bit misleading. But those who really want to know will investigate further than the first few replies. So good luck to anyone who makes it this far. Oh, and thanks to "goobaah" for helping me past the false problems.

 

[sassan]

Well it's a little over a couple of months and still no problems with the IRST. Not even a hiccup. No more false alarms. It just sits quietly in the background and does it's job.

Too bad the Best Answer on this site is a bit misleading. But those who really want to know will investigate further than the first few replies. So good luck to anyone who makes it this far. Oh, and thanks to "goobaah" for helping me past the false problems.

I just came back and I figured out that you had gotten it to work. Now I'm seriously thinking of doing Raid 5. Going to do some research now

 

[Super Dog Help Us]

At this point I think the best answer for your system is:

1. Yes you can convert from RAID 0 to RAID 5 if you have Intel® Matrix Storage Manager software but you may get some false errors after conversion as pointed out by 'goobah'.

2. Installing Intel® Matrix Storage Technology over the old Intel® Matrix Storage Manager will most likely mitigate the likelyhood of 'false errors'.

Note: Most of the time RAID 5 is used for servers since they are critical service points and down time affects multiple customers. If you have the ability to do a system image and timely backups, along with a repair disk, then RAID 5 may be a bit of overkill.