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Problem when adding 4th HDD to Raid5

Last response: in Storage
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October 4, 2009 9:59:22 PM

I have a windows XP machine (32 bit) that I'm now using to store all my DVDs and media. I already had 3 1TB drives set up in a raid which gave me about 1.8TB storage. I bought another drive and since I was having some issues with applications decided to reformat and rebuild the array from scratch (had the data backed up). I'm using an ASUS A8N Sli Premium mobo with a raid5 controller built in. Now the odd thing is this: when I try to create a new RAID 5 group with 4 drives (all the same 1TB drive) it gives me a max size of 746 GB. If I build one with just 3 drives, I get my 1.8TB again. This makes no sense and I can't figure out what to do. Any help is appreciated.
October 4, 2009 11:30:47 PM

ok, the controller on the motherboard only support 46bit LBA (I have that motherboard), meaning that the controller can only see 2TiB of space, you are trying to make it see 2.73TiB

the reason it will show 746GiB is that 0.73TiB above 2TiB, what happens with computers is if a number goes beyond the scope of the size of the number of bits holding the data it wraps around

so to do a RAID-5 on those disks there are two options
1) have each disk separate and use windows software raid (or if in linux mdraid is great)
2) get a raid card (a good one like adaptec) for the HDD's and make sure it has support for 64bit LBA's

i would recommend the 2nd option for two reasons
1) the onboard controller isn't going to be much better (if at all) than software RAID because the actual raid is done on the driver level instead of the hardware level
2) the Sil3114R builtin is on the pci bus along with the marvel Gigabit lan controller (top port) and any other pci device, and they all share the same bus meaning lower performance (use the bottom NVidia NIC since it is attached internally via PCI-Express)
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