Intel R.S.T. RAID - Fake RAID or real 1

[goombawaho]

I always recommend RAID 1 to people that value their data and uptime, but I'm kind of confused as to why some people refer to the onboard RAID controllers (such Intel RST RAID) as "fake" . Isn't it real hardware RAID just like an add-in PCI-E controller only built in to the motherboard?

I know that software RAID is a function of the O.S., but the built-in RAID controllers are certainly not using that.

I thought our little wild time had just begun.

 

[rclarke250]

well, in some ways it is a "real hardware" raid, but it doesn't have a separate processor that controls the raid function, I would say it is a low function and not a high function raid adapter. It in no way can be compared to a SAS adapter from LSI or Adaptec that has battery backup for the cache, and it's own expandable cache memory. But then most people don't need that in a home or small office setting.

 

[goombawaho]

Well, that's what I was thinking and no argument about the higher end discrete controllers for server applications. I was trying to find some reference material on it but I can't find much on the functional differences between the onboard chipset RAID vs. the add-in cards.

I thought our little wild time had just begun.

 

[Sympology]

Not 100% sure, but does the Intel job have seperate controllers, if not it means both disks can't be used semi independantly, i.e. a duplex / multiplex system, increasing the overal performance.

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[technome]

No coprocessor but works off a controller hub...

http://www.intel.com/support/chipsets/imsm/sb/CS-012304.htm

From a paper I read a couple years back Intel RST has an advantage over Lsi and other hardware raids in raid 1. In raid 1, info can be read from either of the disk by the Intel RST. This does not happen on the LSI based cards, where info is read from one of the disk only, an odd behavior, considering the upper LSI raid types read from multiple disks (raid 10, raid 5 etc).

Main differences of a true separate hardware raid..
Coprocessor for parity calcs, relieving the system cpu of the demanding process,less IRQ interrupts.
Less traffic on the system bus as disk system overhead is confined to the raid adapter bus.
support for a large multiple of raid arrays. Support segmenting of volumes.
support for large number of drives
write back cache
many more changeable parameters
battery backed cache
COD. "configuration on disk"
Ability to backup the configuration.
support of raid 50, raid 6, and more depending on manufacturer
advanced error checking
more choices in migrating arrays

Lastly with hardware raid, it does not drive my clients nuts "verifying" the disks like Intel RST does.


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[goombawaho]

Lastly with hardware raid, it does not drive my clients nuts "verifying" the disks like Intel RST does.

Scheduled for 3:00 a.m. on Monday morning, it's not likely to bother anyone but an insomniac.

I thought our little wild time had just begun.