Software Raid 5 array power saving

shaamone · 03-22-2006, 11:35 AM

Hello all

I'm about to set up a raid 5 storage array on ubuntu breezy 5.10 with MythTV 0.19 to act as my media backend / fileserver machine. It will run 24/7/365 (fingers crossed!).

My structure is as follows :

40Gb system disk
3x200Gb disks put together as one raid 5 device (md0)

My thinking is that since the raid array will be used only when it's recording TV / serving files on the home LAN, would I be able to power it down when not in use?

One problem that springs to mind is the hit on my power supply when all three drives start up at once if they've been sleeping (they're PATA).

shaamone · 03-22-2006, 03:06 PM

Surely someone's tried this before?

Electro · 03-22-2006, 04:14 PM

You can not put the drives in power saving mode because it will trash the array. You can look into solid-state hard drives or use notebook SATA hard drives. Servers actually have a seperate power supply to power the array of hard drives. You can get a dual voltage switch-mode power supply at Jameco. Hard drives have a tolerance of about 5% for voltage regulation.

As with all PATA and SATA, you will have to use the hard drive utility from the manufacture to disable automatic location of sectors for a reliable RAID setup. Also disable the built-in cache for each hard drive that are going to be used in the array.

shaamone · 03-23-2006, 02:00 AM

Quote:

As with all PATA and SATA, you will have to use the hard drive utility from the manufacture to disable automatic location of sectors for a reliable RAID setup. Also disable the built-in cache for each hard drive that are going to be used in the array.

One assumes this will be a Windows util. Here's hoping it will run from a live CD. Surely disabling the drive cache will have a negative impact on performance?

shaamone · 03-23-2006, 02:17 AM

Amazingly, Seagate will let you download a bootable iso

Western Digital also have a DOS util I imagine can be loaded from disk. Oh how the world is changing!

Now, next step is to think about how I'm going to squeeze an extra PSU into my case. The four drives I have running are causing system freeze whenever there's a big chunk of disk access

Electro · 03-23-2006, 08:01 PM

You can get a Seasonic S12-600 (600 watts). It is noiseless if you use cork between the power supply and computer chassis, but it is still noiseless if you do not use cork. It can provide up to 600 watts of power from what Toms Hardware said. I have the 430 watt version and it works very, very well.