Topic: Mirroring/Striping as Opposed to Ghosting

[Sandra]

Can someone explain exactly what the advantages of Mirroring or Striping has over simply Ghosting a hard drive ?

How to do this is currently being discussed in this thread :

http://pc-pals.com/index.php?board=28;action=display;threadid=5254;start=0

My understanding of it is that if you "mirror" a drive then it actually updates itself when you add/delete from the the drive that you are mirroring it from whereas if you merely Ghost a drive then the Ghosted image will remain as it was when you first created it.

Is that basically it or have I misunderstood the mirroring thing  

[Adept]

You've got it in one Sandra

Mirroring is an automatic process whereby an exact duplicate of a partition is maintained on another drive.

This means that if one drive fails the other will still contain your data. Once the faulty drive is replaced it can be restored from the mirror drive.

Should a replacement drive not be available, the mirror can be "broken" so that the data on the working drive can be accessed.

[Sandra]

Can this be done with any OS,provided you have the correct software to do so or is it only for the later Windows versions that have the software incorporated in the OS already ?

[lobo]

Mirroring, RAID /Striping as Opposed to Ghosting

Let?s look at the definitions for these objectives.

Mirroring is the creation of a mirror image of your main active drive on to another drive either in the same computer or on a drive in another computer on a network, if data is added to your primary drive then it is automatically copied to the mirror drive, this mirror drive will not be visible in my computer as a drive but is accessed by the drive letter C:\ (If this is your main drive) if one drive fails then the other drive is used to continue working with. (There are ways to install a new drive in a mirror set but that is a bit complicated for now)

Disadvantages of mirrored volumes
Disk-write operations on mirrored volumes are less efficient because data must be written to both disks. However, this performance penalty is offset slightly because writes on both disks can usually take place concurrently.
Another performance penalty occurs when the system resynchronizes a mirrored volume. Resynchronization is the process by which a mirrored volume's mirrors are made to contain identical data. During resynchronization, performance is affected because the computer is performing many I/O operations to copy the data.

NB: Mirrored volumes are not available on computers running Windows 2000 Professional, Windows XP Home Edition, Windows XP Professional, or Windows XP 64-Bit Edition.

Redundant Array of Independent Disks (RAID)
A method used to standardize and categorize fault-tolerant disk systems. RAID levels provide various mixes of performance, reliability, and cost. Some servers provide three of the RAID levels:

Level 0 (striping),
Striping allows the use of two or more drives as one big drive e.g. if you strip a drive of 60Gb and a drive of 40Gb then you get one drive of 100Gb (If my maths are right) this drive will read and write up to 50% faster (probably 30% is more likely) than a single drive, the big disadvantage is that if one drive fails then all the data and programs on the drives are lost

Level 1 (mirroring),
A fault-tolerant volume that duplicates data on two physical disks. A mirrored volume provides data redundancy by using two identical volumes, which are called mirrors, to duplicate the information contained on the volume. A mirror is always located on a different disk. If one of the physical disks fails, the data on the failed disk becomes unavailable, but the system continues to operate in the mirror on the remaining disk. You can create mirrored volumes only on dynamic disks.

Level 5 (RAID-5)
This method of striping three or more drives is the most data secure option because it can recreate a disk set if one drive fails from the data on the other drives

?If a portion of a physical disk fails, Windows recreates the data that was on the failed portion from the remaining data and parity. You can create RAID-5 volumes only on dynamic disks, and you cannot mirror or extend RAID-5 volumes.?

As you can see the RAID set is orientated towards Server use but there are motherboards with RAID capability that can be used in the home environment, these can be useful for game play which requires fast hard drive access and large drive volumes

Ghost Images
Norton Ghost or any other drive imaging programs take a ?Snapshot Image? of a drive or a partition which can be saved to a CD-R or another partition or drive, this image will contain all the operating systems and programs and all the data on that drive/partition, this data image can be in a compressed to about 50% of the size of the data on the original drive, If at any time you add more data or programs then you must make another image


Hope this helps

If you need more help please post or PM me

Thanks

Brian

[Tony]

youz reet enough for me Brian old lad  

Another question, right lets say OS/ data takes up 10GB on a 30GB partition. And lets say you can compress it say 50% for sake of argument. So you store it on  6GB of CD's or a 6GB partition. Am I right to assume you could  then uncompress it onto another HDD which was lets say only 20GB ?

Off to put the tea on, but I'll be back  

[Sandra]

That sounds right to me Tony and a lot easier than al this mirroring too  

[lobo]

Hi Tony
If you ghost the partition/drive then you can burn it to another drive, the image will adjust to the new drive size provided there is enough space on the drive to accommodate it.

Just a point, if you want to do this sensibly then format a drive, install the windows operating system of your choice and all the support programs like office and such. When you have done this run Norton Ghost and image the drive to a CD-R, the image should fit on to one CD.

This should be your basic backup restore CD which you can run at any time to restore your PC to a good working copy with all the programs installed in about 8 minutes.

If and when you install other programs just do another Ghost image and save it to another partition or CD-R (you can not save an image to the partition you are imaging) when you install something else just delete the old image and run ghost again

When you are operating your PC make the default folders for My Documents and other important folders on another drive/partition then all your data will be safe other than on your C:\ drive

Most people only need to backup data, its a waste of time backing up programs because the have to be installed so it make sense to backup your data daily to another source i.e. rewritable CD or CD-R or a tape backup system or just to another drive.

I keep a library of Ghost CDs with the different basic Operating Systems plus Office and other things like Nero and Anti-Virus software installed so if I get a new drive its only matter of minutes before I?m up and running again


Brian

[Adept]

Can this be done with any OS,provided you have the correct software to do so or is it only for the later Windows versions that have the software incorporated in the OS already ?

It can be done with most OS's if RAID hardware is fitted to the PC.

Otherwise it appears to be NT 4.0 Workstation and Windows XP Pro that have the software version and NT 4.0, Windows 2000 & 2003 in the server world.

[Sandra]

From Brians earlier post Adept,it doesnt sound like XP pro will do it either  

[Adept]

Looks like you are right, but I'm sure I've done it before

Ho hum ...

[Tony]

That sounds right to me Tony and a lot easier than al this mirroring too  

Yer me too Sandra

Brian,

that sounds good advice, thanks. I was reading that PMagic can copy a partition, but make the partition smaller as long as the content fit the smaller partition. But you had to do this on a Drive that was in an unallocated state.

Adept, Look if I manage to copy the contents of C and D Drives on to the new 30GB HDD, I'll have a bash at mirroring just to see if it can be done with W2K Pro. Acid test so to speak, just to settle the argument. Though I accept nobodies arguing in the true sense of the word.

Unfortuneatley I cannot get around an error on my Drive Image program. Looks like its time to read up on Norton Ghost.

And Partition Magic, keeps throwing up error 58 'unable to write to boot sector, virus protection software may be running'

Ho Hum like I've said before I'm crap with software  

Thanks one and all

[Adept]

Adept, Look if I manage to copy the contents of C and D Drives on to the new 30GB HDD, I'll have a bash at mirroring just to see if it can be done with W2K Pro. Acid test so to speak, just to settle the argument. Though I accept nobodies arguing in the true sense of the word.

Don't bother Tony, I've looked it up on th eM$ knowledgebase and you definitely cannot do it with Win2K or XP Pro I think my confusion has come from the fact that you can use Win2K and XP clients to mirror drives on a Win2K server.

That's my story and I'm sticking to it. Like Sandra, I am never wrong, just sometime unaware of all the facts

[lobo]

Hi Tony
'unable to write to boot sector, virus protection software may be running'

When ever installing software disable the anti-virus program it prevents the installer from writing file to the appropriate location

Some motherboards have a built in Anti-Virus system which should also be disabled in the BIOS before running software that may require access to the boot sector

Brian

[Tony]

Tried all that Brian last night, maybe GoBack needs to be disabled. I nearly did it today but cancelled it right at the last second.

See I'm basicaly addicted to GoBack as it has got me out of the Sh*t many times. Only prob with GoBack is if you disable it you lose all records of previous configerations. I get this nightmare in my head, whilst it is disabled I cock up, see I'm breaking out in a cold sweat again.

[Reno]

while reading through this thread i thought i might lend some advice. Download Knoppix. Its linux and free. what knoppix does is loads itself in ram, auto configs the hardware drivers and opens a gui without writing to the hd. So for instance if you computer gets screwed and you cant boot into windows you can go in and retrieve information without worrying about certain contamination. It becomes handy when access computers that u've forgotten the password to and/or breaking into. very useful in retrieving information. u can set weither or not to write to the hd also in the hd properties.
I have had comps with completely crap out registeries and just copied a fresh installation into place in 10mins or less. Which comes in handy when u want to restore the registery and not write over the information on the disk. Last time i looked though it wasn't compatable with NTFS partricians, but that was about a years ago and i don't use XP or nt.

If u want to ghost an entire hd to cd that say is more than 20gigs or more of infomation. u can save the image to the hd and spit the image file up using winrar. and just burn the individual winrar files to cd.

I like the idea of ghosting better than mirroring just because ghosting seems more independant. I just wounldn't feel secure mirroring compared to ghosting. i would rather ghost something onto cd or another hd and keep it tucked away in my closet compared to having a mirror on the same hd. It seems problems most of the time effect the entire hd and not just one partrician. I also don't use raid so i wouldn't i doubt i would be burning the mirrored partrician to another hd. I have used PMagic but it seems far too dangerious to go playing around with when u could just ghost the hd.