|
PureBytes Links
Trading Reference Links
|
Try http://www.promise.com and Raid 1 configuration. I have been
considering this, but would like feedback from anyone already doing it.
bobr
----------------------------------------------------------------------------
-------
This article offers a quick overview of RAID and RAID terms.
a.. RAID Levels
What is RAID?
to top
In a standard PC, each hard drive is seen as an independent disk designated
by letters like C,D,E, etc. In a RAID system, multiple hard drives are
placed into one or more "arrays" of disks. Each array is seen as an
independent disk, though that array may include upwards of two, three, four,
or more drives. This is why RAID stands for Redundant Array of Independent
Disks. In an IDE RAID array, of course, the drives are low-cost IDE.
Promise IDE RAID also uses advanced data handling techniques that takes
advantage of the fact that multiple drives are performing the work of a
single drive. This includes tagged command queuing/scatter-gather/elevator
seek which basically re-orders requests for data depending on their location
on the hard drives. This provides more efficient use of the read/write
heads, particularly in retrieving data.
RAID Levels
to top
Using RAID arrays inside a PC offers much greater flexibility, depending on
application usage. Different RAID levels perform different functions.
RAID 0 (known as "striping") basically links each drive in the array as one
huge drive. Storage capacity is determined by the smallest drive in the
array. That capacity is then applied to format all other drives in the
array. If using a 4GB, 6GB, 5GB drive in a RAID 0 array, your system will
see one huge drive of 12GB (4GB x 3) versus 15GB. RAID 0 offers double or
more performance under sustained data transfers when one drive per IDE port
is used. In such a configuration, unlike SCSI, IDE drives are always
available to the system. SCSI requires more management of the SCSI bus.
Spanning: If a user wishes to obtain all the capacity of the drives in an
array, he may also choose to "span" the drives. Unfortunately, there are no
other benefits except capacity with the spanning solution.
RAID 1 (known as "mirroring") makes and maintains an identical image of data
from one drive to a second drive or from multiple drives to a second set of
multiple drives. Should one drive fail, the working drive or drive set
continues operating. To the system, such an array is still seen as a single
drive letter. While RAID 1 is the least efficient use of hard drives to
provide data protection (since the user does not see any of the additional
storage capacity of the mirrored drives), low-cost IDE makes it acceptable.
If performing 1-to-1 mirroring with two 4GB drives, the system only sees one
4GB drive. IDE RAID 1 represents a significantly lower cost than SCSI RAID
1.
RAID 5 uses a mathematical expression that compares data from two drives and
calculates a third piece of data called "parity". Should one of the drives
fail, parity data can be used to rebuild the failed data. Under RAID 5,
parity data is stored across all drives in the array. This maximizes the
amount of storage capacity available from all drives in the array while
still providing data redundancy.
----- Original Message -----
From: "Bilo Selhi" <citadel@xxxxxxxxxxxx>
To: <systems-only@xxxxxxxxxxxxx>; "Omega List" <omega-list@xxxxxxxxxx>;
"Code List" <code-list@xxxxxxxxxxxxx>
Sent: Saturday, June 02, 2001 9:29 AM
Subject: CL_off topic / image or mirror drive software needed
> list,
> i need a pointer on the following matter.
>
> i need to be able to make a back up or image or
> mirror copy of
> my master drive, say once a week or a day...
> in case of failure of the main drive or corrupt
> operating system i want to be able to
> plug in the mirrored drive and boot to it in
> a matter of minutes.
>
> so, i got me a second drive and i the removable
> tray and all.
> but i lack good software to be able to do it.
> i have dos based "drive copy" and "drive image"
> but those don't work real well ( i get errors
> while copying drive, etc ) and i don't feel comfortable
> using it.
>
> the question is:
> - is there a reliable way to back up or mirror or
> image your hard drive onto another hard drive
> so that in case of sudden failure for whatever
> reason i can just plug in the back up drive, boot
> up to it and i am ready to go in under say
> 10 minutes...
> needs to be ***reliable, fast and simple to use
> and win2000 compatible or dos...?
> - is there software that does that reliably and
> specifically designed to do that on win or dos
> operating system?
>
> i want to be able to make the exact copy of
> the master partition which contain the operating
> system every day or at least every week
> reliably?
>
> maybe drive duplication software or something like that?
>
> so far i have found novabackup and xactcopy but
> was wondering if there is anything else out there that
> will do it.
>
> thanks.
> bilo.
>
>
>
> The Code List -
> Subscribe/Unsubscribe
> http://www.markbrown.com
|