Back up for RAID 0 system

Hi. I work at home.
Question: I have two RAID disk controllers on my computer. The OS is on one controller in RAID 0 (4 Raptors) for speed. I have a large spare disk on the other controller. Can I use your software to back up my entire RAID 0 OS to the spare disk. Will I be able to reload the RAID 0 in case I need to change one of the disks in the array of the OS? In the case I had to change one Raptor, how will the reload work? I will have to boot with the back up disk and then what? Thank you

 

Hi Francois, welcome to the Forum

I am not going to answer your question in this post because I first need to clarify something else in your post.

In your post you stated....

Firstly, independent tests have shown that peformance improvements in an OS that is on a RAID 0 configuration are minimal at best and probably non-existent.

Secondly - and more importantly - RAID 0 is not really RAID at all because not only does it offer no protection, it in fact doubles the risk of failure with every disk in the array. For example, let us assume that a disk has an 7% chance of failure in a period of 3 years. If you have 2 disks the chance of failure becomes 14%; 3 disks becomes 28%; 4 disks becomes 56%.... (The calculation is more complex than this but this is good enough for an illustration). In your case your system is 8 times more likely to fail than a system using a single disk.

In your post you say....

In a RAID 0 configuration you cannot change one of the disks. From an operational perspective all 4 disks form a single disk with a single partition. The data on the disks is "striped" across the disks which means that the integrity of the data is totally dependent upon the entire array. This is the reason why RAID 0 is not RAID. RAID stands for "Redundant Array of Independent Disks" and quite obviously from what I have said above the disks in a RAID 0 configuration are NOT independent.

Therefore the question you ask is one that does not have an answer.

If you want advice as to what you should do so as to ensure a stable, reliable, dependable system then please come back to the Forum and I or another member will take the discussion further.

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Francois

You should have no problem restoring if you had to replace one of the drives. Now here is my issue, which may help or not:

I have a Raid 0 with two raptors on an Intel ICH5R controller. I could not restore using TI10, because it said that the image was corrupt. SO...I had two other options. I have an older backup of my system using Norton Ghost 2003 (DOS version). And I had a more recent backup of my system using Norton Ghost 9.0. Both were able to restore the system.

Ghost 2003. Restored, but first I had to go into an old Win98 boot disk and partition the two drives as one. Then Ghost 2003 restored flawlessly with a DVD backup set

Ghost 9. I had to hit F6 on bootup and put the Controller drivers in the floppy drive...then Ghost 9 recognized the entire array size.

When I tried to restore using TI10...I used the Ghost 2003 procedure and then TI10 recognized the array as ONE drive and proceeded. However, as I said...the image I created was corrupt, so I will never know. At that point, I went back to using Ghost 9, which has really never failed me. I got TI10 in anticipation to Vista...then I just found out that Ghost 9 will work with Vista, so TI10 sits in a drawer and will collect dust. Too many issues with corrupt images...

Bob

 

Posted by Peter2150...

It is not about the terminology it is about the technology.

There is a normal expectation that when you purchase something it "..will do what it says on the tin.." Non-technical uses, or even technical users with no experience of RAID, have an expectation that RAID will provide them with a higher level of resilience. Users expect that a "Redundant Array of Independent Disks" is exactly that - namely that the disks are independent. Therefore if Disk_3 in a 4-disk array fails the expectation is that one can simply replace the disk and the array will rebuild itself. And that was the whole design principle behind RAID. Therefore RAID 0 is an invalid and incorrect use of the term.

The entire matter of RAID 0 is currently being investigated by the IEEE and the early recommendation seems to imply that RAID 0 should be removed as it does not conform to the most basic of RAID requirements.

Posted by Peter2150...

I absolutely agree. And that is one of the major drawbacks of a RAID 0 configuration in a home or small busines environment. There is simply no safe way to test the backup - unless of course you go out and purchase a complete set of spare disks, which in the case of Francois would be a very expensive option (4 x Raptors).

If you create a backup of the RAID Array and then test-restore the backup back to the Array you run the risk of ending up with an unbootable system should the restore fail.

Posted by Peter2150....

I am pleased to read from your post that you have experienced a performance improvement. However, this should be seen as a fortunate exception rather than the norm. Extensive testing done by independent testers in controlled environments have concluded that there is minimal, if any performance benefit in a RAID 0 configuration in a home or small business environment. In fact increasing RAM or purchasing an improved Graphics card showed immediate and substantial performance benefits far in excess of anything that was achievable through RAID 0 or even installing faster hard disks.

The concensus of knowledgeable opinion is that, in a home or small business environment, the risks posed by RAID 0 far outweigh any perceived benefits. The recommendation is that RAID 0 should only be used in non-critical environments where Read-Only access is required over a busy network and should not be used for an operating system.

For example, a recommended use of RAID 0 would be where a very large pool of Read-Only data is simultaneously accessed over a network by many users. In this scenario, it would be beneficial to split the data over several disks and then configure those disks as RAID 0. This arrangement would result in significant performance improvements, especially when many users are requesting data reads.

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RAID may indeed stand for "redundant array ..." but I have experienced a 20% improvement in my disk throughput using RAID 0. Acronis works like a charm, including emergency restores (I tried it as a test before I rebuilt my system)

The critics are correct in one respect. If one of the drives fails, you won't know which one it is. We will probably have to dismount each drive and test it in another PC to identify the bad one or, buy a new drive and swap it out with one or the other until you can reload the partitions successfully.

 

Interesting thread (i'm a newbie...)

Whilst i do not agree with all (100%) from Pete, he passes a PEARL OF WISDOM that i recommend to all IE do your RAID 0 then forget about the hardware and simply treat it as a single partition - just as the OS does.

I have multiple OS on multiple drives with lots of partitions. I used Drive Image for years with no problems moving OS from partition to partition (regardless of drive) and i even have most of my programs on a separate partition and the links are retained to the OS where i installed them. I simply ignore my original setups of the hardware for RAID!
So why am i moving to TI - i hear you ask- well VISTA upgrade advisor told me that Drive Image will not work and Acronis told me their imaging s/w will work - so here i am. About to re-image the whole of my setup. I hope this TI is ready for me hehe

(another Pete)

 

Bob,

Do you have a reference or have you personal knowledge. I'm very interested in whether Ghost 9 will work with Vista but I can't find a definite yes or no.

 

Posted by Pete2150...

Let us put RAID 0 aside for minute. Assume any system that has a single disk. Let us also assume that the user stores backups on some external media. For the sake of simplicity let us ignore data files and backups and consider only the OS and Programs and the associated backup which has been created using the "Image" process.

Problem : How does a non-technical user test-restore the OS and Programs safely and legally? (Legally means within the EULA).

There is simply no way that a non-technical user can test-restore the OS and Programs safely and legally with a single-disk system. If the user test-restores back to the source partition there is always a risk that the restore will fail. If the restore does fail then the user will be left with an unbootable system because the first thing that ATI does when it restores a partition is "wipe" the partition. If the user test-restores back to another partition on the same disk they will be in contravention of the EULA. (There is also the techy bits like setting the Active partition and changing the boot.ini file, which may not be a simple task for a non-technical user).

The only safe, simple and legal way to test-restore the OS & Programs is to test-restore back to another disk. Which in the single-disk system of this example is not possible. Therefore, in terms of this example, the user cannot test-restore the OS & Programs partition.

Testing is possibly the single most important step in any backup strategy. If you don't test you can never have certainty that things will work the way you expect them to.

Now back to RAID 0. It does not matter if you have 2, 4, 8 .... or 'n' disks in a RAID 0 Array. From the perspective of the OS you have a single disk. Therefore, the limitations as discussed above apply equally to a multi-disk system that has been configured as RAID 0 as they do to a single-disk system.

All of the above is probably totally irrelevant to Pete, Bob and others on this thread because they all seem to be technically competent. But the vast majority of computer users are not technical and for them it is essential that they are able to recover from a disaster quickly, easily and without stress.

 

Tabvla,

Which EULA? Acronis or Microsoft?

 

Microsoft.... see extract from EULA below

In addition a Windows XP system may become unstable if 2 instances of XP that use the same Product Key are visible at the time of booting. In practice there does not seem to be any consistency in this behaviour. I have seen systems that will boot without any problems and other systems that will instantly blue-screen. The best advice is simply don't have 2 instances of XP that use the same Product Key visible at the time of booting.

Again we are considering the non-techncal user. An unstable XP may be a big issue for someone with limited technical ability.

 

Thanks for that. I understand that Microsoft have difficulty interpreting that EULA when WinXP is being dual booted and one partition is hidden. Sometimes it's accepted for WPA and sometimes it's not. I'm advised that if you are refused WPA (phone) then just call back in 5 minutes and talk to someone else.

The situation with running WinXP from a Virtual Machine is clear cut. You need two licences.

 

Sorry for going off topic. This thread should be split.

I agree with this bit.

For single user patterns of application usage RAID 0 provides somewhere between a negative and a small positive benefit. Overall the benefit is probably not worth the cost. (see various tests and FAQs at http://www.storagereview.com/ for more details. Other tests show the same results).

For example:
http://faq.storagereview.com/SingleDriveVsRaid0
http://www.storagereview.com/articles/200406/20040625TCQ_5.html
http://www.techreport.com/reviews/2004q2/chipset-raid/index.x?pg=27
http://www.anandtech.com/storage/showdoc.aspx?i=2101&p=11

Now at this point people will say "HDTach (or other synthetic benchmark) shows me a 30% improvement!" Yes you are right it does improve benchmarks that measure sequential transfer rate and as a consequence there are some benefits for example level load times for games are sometimes reduced (depends on the nature of the level information being loaded. Very large sequential transfers clearly working well.)

Tabvla was expressing frustration at the myth of the great benefit of RAID 0 (Redundant Array of Inexpensive Disks was the name when I was a lad but the Inexpensive thing wasn't true so got changed) and also the contradiction contained in the R of RAID being used with 0 however I think it belonged in another thread.

 

Pete, I've never experienced that situation. If any backup software failed in its restore function I'd remove it from the computer immediately and move to another product. You shouldn't have to test to see if images restore, they must restore, every time.

 

Consider the Managed Backup Locations function; it's nifty.

If you do a test restore, then you know it is fully funcitonal on your machine. Short of that requires a bit more faith. For some places, a test restore is part of the security protocol as it applies to backups. As Hank Ketcham used to say, "You sure can't tell how deep a puddle is until you jump into it."

regards,
sh

 

I have a question Regarding RAID 0.

I have My OS currently running on on a RAID 0 Array (2 250GB drives on an nVidia MediaShield Controller, integrated on a nForce 650SLI mainboard.

Is it possible to make an image of the OS partition using TI or Ghost, then convert back to single drives (in preparation of a dualboot with Vista) and restore, without going through the hassle of reactivating windows and FSX? I have already been on the phone with them once this weeks, and that was such a hassle (they really do treat you like a criminal!).

RAID 0 seems a bith more responsive, but the risks and the hassle afterwards may no longer be worth it to me...

 

Hi!

Technically when you do the boot-CD imaging (you need new enough a version of True Image for it so that it recognises the raid drivers), there is no problem going back and forth bios-configured raid.

Only caveat is, that your Windows has to have the drivers for the new setup installed beforehand. This is not an issue if youre moving away from raid, but if you move from single disk ==> raid array, you have to install the raid hardware/drivers (even when you're still running on single disk) before doing the backup/restore.

I did this several times on Vista x64 using NVidia raid and trying different drive counts for raid 0 and different block sizes.

Now my memory might not serve me properly on this, but I'm pretty certain that when I moved from single disk ==> raid, I had to reactivate my Vista. When staying on raid and playing with the drive configurations (and backup/restoring in between), Windows didn't see any changes and didn't need the reactivation.

Of course Vista may behave differently than your OS.