RAID

  • Thread starter Thread starter Mofaz
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Mofaz

Alright, so I have to SCSI HDDs which I've hooked up to a Promise PCI
RAID adapter. The array is set to mirror. Now, after having this
setup for quite some time, I'm beginning to wonder how I can just set
it up to where I can link both HDDs together to combine the storage
space. So, instead of just having one mirrored 60 GB HDD, I would
have 2 60 GB HDDs for a total of 120 GB of hard disk space. How do I
go about doing this? Is there any equipment that I need to buy?
 
Mofaz said:
Alright, so I have to SCSI HDDs which I've hooked up to a Promise PCI
RAID adapter. The array is set to mirror. Now, after having this
setup for quite some time, I'm beginning to wonder how I can just set
it up to where I can link both HDDs together to combine the storage
space. So, instead of just having one mirrored 60 GB HDD, I would
have 2 60 GB HDDs for a total of 120 GB of hard disk space. How do I
go about doing this? Is there any equipment that I need to buy?
Click to expand...

RAID 0 combines the space of the two disks.

You've been using RAID 1, where one disk is a mirror or exact copy
of the other disk.

You need to back up your data to a third hard drive, before you
go any further.

Once your data is backed up, then you can delete the existing array
on the Promise controller, then create a new array of type RAID 0.

The RAID 0 array will need regular backups, because it is unprotected.
While using RAID 0, if one of the two drives fails, all data is lost.

For some background material on the various forms of RAID, Nvidia
has a document for their Mediashield software. Note that there
are two potential ways to do what you want. You can use RAID 0
or you could use JBOD mode. The difference is, that RAID 0 alternates
between the drives, and you get twice the I/O bandwidth. In the
JBOD mode, all of one drive is read first, before moving to the
next drive. And chances are, the Promise controller doesn't support
JBOD mode, so you will be using RAID 0 anyway.

Nvidia Mediashield manual, with some info on RAID...
http://www.nvidia.com/object/IO_28159.html

You don't need to buy any equipment, but I would buy a spare disk
drive, on which you make frequent backup copies of the data on
the RAID 0. Operating a RAID 0 without backups, is crazy.

Paul
 
You just need to assign the two harddrives into a RAID 0 array, instead of
the RAID 1 array you have now. Then reformat, and install your OS.
 
DaveW said:
You just need to assign the two harddrives into a RAID 0 array, instead of
the RAID 1 array you have now. Then reformat, and install your OS.
Click to expand...
Most set-up software allow JOB. Just A Bunch of disks.
JPS
 
RAID 0 combines the space of the two disks.

You've been using RAID 1, where one disk is a mirror or exact copy
of the other disk.

You need to back up your data to a third hard drive, before you
go any further.

Once your data is backed up, then you can delete the existing array
on the Promise controller, then create a new array of type RAID 0.

The RAID 0 array will need regular backups, because it is unprotected.
While using RAID 0, if one of the two drives fails, all data is lost.

For some background material on the various forms of RAID, Nvidia
has a document for their Mediashield software. Note that there
Click to expand...
Paul,

When using RAID 1 is it normal to not see anything written on the
drive which is mirroring the master drive? I think I read somewhere
that it is normal, but I'm not sure anymore since it's been a
loooooong time. Man, I used to be pretty sharp on this stuff.
 
Mofaz said:
Paul,

When using RAID 1 is it normal to not see anything written on the
drive which is mirroring the master drive? I think I read somewhere
that it is normal, but I'm not sure anymore since it's been a
loooooong time. Man, I used to be pretty sharp on this stuff.
Click to expand...

If a RAID 1 is working properly, the controller will write to both
drives at the same time. Each drive should contain exactly the same
information - that is why it is called a "mirror", as it is
supposed to be an exact copy.

If the mirror has a status of "broken", then you may see the
second drive no longer doing write operations. What is the
current status of the array ? Is it "healthy" or is it "degraded"
or "failed" ?

Paul
 
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