Dual RAID for system and data drives

  • Thread starter Thread starter jerryhole
  • Start date Start date
J

jerryhole

I am building a PC and want to use RAID 1 to mirror the system disk
and RAID 1 to mirror a data disk. The plan is as follows:

System disk:
One 300GB SATA HD mirrored to a second 300GB SATA HD using RAID

Data disk:
One 1.5TB SATA HD mirrored to a second 1.5TB SATA HD using RAID 1

I gather that I should use a RAID controller card rather than the MBs
onboard RAID as a RAID controller card will have its own processor and
the MBs onboard RAID will use the CPU. Please correct me if I am wrong
on this.

So, can RAID controller cards handle this configuration or do I need
to use two RAID controller cards? Maybe it is one of those things that
everyone knows and thinks everyone else does as well. Anyway, I can't
find a clear answer on this.

Thanks in advance.

Jerry
 
(e-mail address removed) kenjka:
System disk:
One 300GB SATA HD mirrored to a second 300GB SATA HD using RAID
Click to expand...
Data disk:
One 1.5TB SATA HD mirrored to a second 1.5TB SATA HD using RAID 1
Click to expand...
I gather that I should use a RAID controller card rather than the MBs
onboard RAID as a RAID controller card will have its own processor and
the MBs onboard RAID will use the CPU. Please correct me if I am wrong
on this.
Click to expand...
So, can RAID controller cards handle this configuration or do I need
to use two RAID controller cards? Maybe it is one of those things that
everyone knows and thinks everyone else does as well. Anyway, I can't
find a clear answer on this.
Click to expand...

They can use this kind of configuration... My suggestion is to stick with
true hardware RAID controllers like 3Ware 9650 series (for PCI-Ex) and 9500
series for PCI/PCI-X... You can use 4-channel controller for your
configuration...

BTW., check the 1.5TB drives if they can work with your RAID controller,
since some Seagate drives had problems when used in RAID configuration, or
at least I've heard that way... There are quite a few people on this group
who can tell you more about Seagate behaviour...


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By runf

Damir Lukic, calypso@_MAKNIOVO_fly.srk.fer.hr
http://inovator.blog.hr
http://calypso-innovations.blogspot.com/
 
Previously said:
I am building a PC and want to use RAID 1 to mirror the system disk
and RAID 1 to mirror a data disk. The plan is as follows:
Click to expand...
System disk:
One 300GB SATA HD mirrored to a second 300GB SATA HD using RAID
Click to expand...
Data disk:
One 1.5TB SATA HD mirrored to a second 1.5TB SATA HD using RAID 1
Click to expand...
I gather that I should use a RAID controller card rather than the MBs
onboard RAID as a RAID controller card will have its own processor and
the MBs onboard RAID will use the CPU. Please correct me if I am wrong
on this.
Click to expand...

CPU is not really the issue. Software-RAID, for example works well.
There is a different reason not to use the on-noard RAID: It is
typically cheaply implemented and unreliable. Also, when the board
dies, you may be in trouble. Moving to a new mainboard can be
problematic.

The general issue with hardware-RAID is that you should keep a spare
controller card around, in case the card dies. Better RAID cards will
at least move the REAID superblock to the end of the device (lInux
software RAID also does this) so that the individual drives
can be used and remain bootable in case of controller failure.
So, can RAID controller cards handle this configuration or do I need
to use two RAID controller cards? Maybe it is one of those things that
everyone knows and thinks everyone else does as well. Anyway, I can't
find a clear answer on this.
Click to expand...

It really depends on the card. If you want genuine hardware RAID,
you are in higher cost teritory. Many cheap RAID cards are actually
software (or better BIOS) RAID. In any case, some cards will be able
to do it and some will not.

My recommendation would be to have a good look at software RAID
first. Might be easier to handle (and can be done on partition
level too). The performance loss should be very small for RAID1,
unless you have a very slow SATA controller. I have been operating
even RAID6 in software and the CPU load was moderate. With a 2 or 4
core you should not even notice it.

The big advantage is that you can typically move a software RAID array
from one machine to another in case of hardware failure. The one thing
that can be tricky is whether you get automated booting if the primary
drive fails. That depends on the software RAID. With Linux it is quite
possible, and it may be possible with Windows. It should be possible
with OSX as well.

If unsupervised booting is not the issue, you should allways be
able to just boot from the remaining disk manually.

Some more points:
- RAID is not backup. If you mess up or malware strikes, you can still
lose all data.
- RAID is best operated with hot/cold spares, i.e. replacement
disks kept in the machine or in the cupboard.
- 1.5TB sounds like Seagate. They have problems with their firmware
at the moment. It is unclear at this time whether the issue is
being successfully resolved. New drives may not be affected, but
nobody is sure.

Arno
 
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