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Hi,
My server has an SSD for / and three HDs in RAID-5 on an old Adaptec 2610SA raidcontroller. This works very well and speeds are good, but I cannot compare. The problem now is that I'm not able to make the HD's spin down with hdparm - they should only be used when accessed, but I hear them spinning up all night long, every 30-40s.
hdparm complains about I/O errors when used on the raid array.
I'm thinking of plugging the disks into my motherboard with Intel ICH10R-chipset, also capable of RAID-5.
Three questions:
* Speed: can someone make an estimate if the speeds will be the same or not? This is not that important.
* energy-efficiency: probably better because an extra card in my server can be taken out - maybe hdparm works on the newer controller? Any comments?
* Is RAID via the ICH10R-controller 'software raid' or 'hardware raid' - I know calculations are made by the CPU, but it has a dedicated controller, no? Should I use dmraid for this?
I generally don't mind experimenting, but the wife is killing me with work throughout the house, and time is very scarce at the moment...
THX!
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Hi,
I can't answer your questions exactly, but I never had any problems in terms of speed with my SW-Raids. One of them is running on an Intel-Atom board with only 2GB of RAM and it's "fast enough". In my opinion the main reason for preferring SW Raids upon HW-Raids is that they are portable. For example if your MB dies, just reattach in a different System and everything is up again... I don't think you can afford that with any HW-Raid, even not if they are just Fake-HW-Raids like some Controllers do.
regards,
gnux
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Thank you for you reply - you have assured me already. As I said, speed is not my main concern: Although I have a gigabit network at home, it will still be a bigger bottleneck than the speed of the hard disks if they are set up correctly in any type of RAID.
I am still interested in other opinions - any energy saving tips?
Vincent
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Get something like a Kill-A-Watt and test the server with and without the hard drives - is there really that significant of a difference? I would be more worried about the lifespan of the drives than the energy consumption. If you want to save energy, depending upon your setup, you could try putting the server to sleep (or shutting it down) when you're not using it.
Edit: Oh dear, I haven't answered your question. I doubt you'll see much of a performance difference. 3 hard drives is not many in a RAID array, so the bottleneck is probably I/O, not parity calculations.
Also, the "hardware" raid on your chipset is fakeraid. I would just use the software RAID that's standard with Linux, with mdadm.
Last edited by Tempest (2012-10-19 03:06:40)
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Thank you for your insights - I'm learning a lot and can start experimenting.
Yesterday evening I noticed that the powerdown (AUR) script with hdparm does work to keep the drives spun down.
Putting the server to sleep is something I have been contemplating for a long time, but since I'm using DLNA, I'm not sure I can wake the server (f.e. through WOL) by sending a 'magic packet' with a DLNA-device, f.e. my ps3 or smartphone...
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