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Greetings all,

I have been configuring my RAID5 array of 4x1TB hard drives on my Windows Server 2008 (software array).

How long does it normally take to format when using the normal Server Management interface ?

I am asking this because of the time it is currently taking. It's been half an hour or more and it now shows 1%... Strange.

Thank you for your anwsers.


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"How fast is a 1Tb disk". Same question. – Chris Thorpe Nov 4 '10 at 0:15

Entirely depends on the controller, the drives (speed), load on the server, processor speed, memory (since it's software RAID), disk interface...

As long as the system isn't registering any errors in the logs it should be okay. You can try watching the performance monitor to make sure that the disk I/O and processor aren't showing odd activity.

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I set up a new server with 6 x 650 GB raid 5 with one disk as a hot spare and it took about 20 hours to format and sync the first time. YMMV but that is my ballpark number, the server was not under any application load.

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I vaguely remember hearing something about Windows refusing to quick-format anything over 2TB so that means it is reading and analyzing every sector of the array to format it. A coworker formatted a 16TB array and it took about 3 days. So, based on that highly inaccurate estimate, you will be waiting another 17.5 hours. Of course, that was with hardware RAID so this might take significantly longer.

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If you're creating a RAID array with a level other than RAID0, the entire disk must be written to to create the array before you can even begin formatting (putting a filesystem) on it. – Slartibartfast Nov 5 '10 at 3:27

Rule of thumb, assuming you are not CPU bound (if there are no single CPUs at 100% usage all the time, this means is the case for you) is that creating a RAID5 array will take about as long as it would take to fill a single drive. If that is not the case, I would probably blame the disk controller as a first guess.

Actually, I think that rule of thumb applies to all RAID levels (1,5,6,10,60,50) I'm aware of other than 0 assuming the tool building the array does it optimally.

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