Reduced RAM amount when using RAID?

[pbmaster]

I just got my RAID setup yesterday, and I noticed that several programs report 4086 MB of RAM. I know that it's not supposed to see exactly 4096 MB, but before I was using RAID it saw something like 4094 MB. Does running RAID reserve a small amount of RAM? I know 10 MB isn't that much, but I'd still like to know what's going on. Thanks!

 

[newfellow]

That's actually exact 8MB. Wonder what RAID controller are you using. I know Intel ICH9/10R nor NVIDIA nforce won't take RAM, but there could be something 'new' I haven't heard of.

Not exactly sure on AMD790/SB750 chipsets. Never had one, but good info, if so.

 

[Kursah]

Could be a detection glitch when Raid is active maybe? I've never noticed that, but I only tried raid for a few months, left dissapointed beyond benches for my uses. Maybe contact Asus and see what they have to say about it?

 

[pbmaster]

I'm not really concerned as long as more of my RAM doesn't start magically disappearing. My buddy who works at a local PC shop said it was something to do with the ATi card and Vista x64...not too sure other than that though.

 

[Bundy]

That's actually exact 8MB. Wonder what RAID controller are you using. I know Intel ICH9/10R nor NVIDIA nforce won't take RAM, but there could be something 'new' I haven't heard of.

Not exactly sure on AMD790/SB750 chipsets. Never had one, but good info, if so.

How do you know that ICH9/10 don't take RAM? I'd be intersted to read.
As far as I understand, onboard RAID uses the CPU via drivers that are loaded prior to the OS. It might be possible the missing RAM is those drivers. IDK

 

[Maban]

I'm getting a few drives for Raid 5. Getting two Monday and the other will be Tuesday. If I remember and if it hasn't been explained I'll post my results.

 

[pbmaster]

I could be totally off on this, but it makes sense that some of the RAM could be reserved for the RAID drivers. And again, it's only 10 MB. I'd just like to know where it went.

 

[phanbuey]

hmmm I have raid and all me ram is there... but then again I have nvidia... Ive never heard of raid array taking ram and locking like a onboard gfx or something- sure the driver may use ram, but I doubt that it would make the ram totally invisible to applications. they should still detect all of it, even is some of it is used by the driver.

In short. I dunno... but RAID isn't supposed to take any ram and hide it from the system. But every controller works differently so IDK. Has the googles turned anything up similar with that MB?

 

[Meow9000]

Write cache reliability
Some RAID systems use RAM write cache to increase performance. A power failure can result in data loss unless this sort of disk buffer is supplemented with a battery to ensure that the buffer has enough time to write from RAM back to disk.

Might answer your question

 

[pbmaster]

I understand that software RAID uses RAM along with CPU time, but what I'm trying to figure out is if it results in less total RAM reported. In every sort of diagnostic 4086 MB RAM is reported, instead of the 4094 MB that previously was.

 

[phanbuey]

if it is the only thing that changed, than chances are that it is the cause of ram being reported incorrectly. When software, even drivers, use RAM - very seldom is it hidden in a way that the system fails to report it to applications that ask for the total amount of ram. Even unavailable ram is usually reported in system diagnostics.

 

[95Viper]

I have 4094 total and 4096 installed. I have Intel Raid using two drives.



You don't by chance have any bios or other shadowing options in the bios set up turned on?

 

[Maban]

RAID 0 here and still 4094. Forgot to check when I tried 5.