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Intel Storage RAID5. What does "Initialize" do?

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September 28, 2011 2:17:43 PM

Hi All,

I've installed RAID5 with 3 disks using Intel Rapid Storage. The volume got created fine and I am able to use it. I noticed, however, that "Initialized" field says "No" and there is an "Initialize" command next to it.

Question is: am I required to perform the initialization to enable RAID5 protection? Or initialization is only required to restore volume consistency after ungraceful shutdown, etc...?

I would imagine that RAID5 redundancy is active from the time the volume is created, but still want to be sure.

Thanks
a b G Storage
October 4, 2011 2:48:12 PM

Initialize will wipe out data. Contact Intel Tech support with exact product details for support.

Ordinarily initialize is only used when first creating a RAID array.

I think it might say no as an indication that you have not requested it to initialize at this point in time; not that it never has been initialized - but I could be wrong.
a c 120 G Storage
a c 128 å Intel
October 5, 2011 12:43:59 AM

If you install a hdd and windows does not see it then it needs to be initialized. When you initialize you are setting the partition size and then you would format that partition. If your drive is already partitioned and formated then windows will see it. If you are building a computer or changing your hdd setup and you create a raid and then load Windows 7 it will partition and format the drive.
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October 12, 2011 5:16:20 PM

NetworkStorageTips, thanks. I chose to initialize the volume and after the process has finished it now says Initialized. Still not sure why it didn't initialize automatically. The process took a few hours and I didn't loose any data.
October 12, 2011 5:17:52 PM

inzone, thanks. I could see the volume in Windows and access it. What confused me was its not-initialized status.

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a c 415 G Storage
a b å Intel
October 12, 2011 5:25:26 PM
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I'm not too familiar with the Intel RS stuff, but I can tell you this. The redundancy in a RAID-5 volume comes from the parity information on the drive. That information has to be written in order to be valid, and that process will take quite a long time (hours) for a modern with capacities measured in TB. If, during the process of setting up the drive, it hasn't gone through that lengthy initialization, then you don't really have redundancy.

Now there's a school of thought that says you don't have to initialize the parity information because when you first set up a drive none of the sectors on the logical volume are actually used for anything, and as you write the first bunch of data to each of those sectors the RAID controller will generate the correct parity for them and write it. So even though the parity information for most of the drive is not valid, it should be OK for all of the sectors which have actually had data written to them.

I don't subscribe that that idea because one of the things that a decent RAID subsystem should do is background parity checks of all the sectors on the volume. That's how you find out about problems before it's too late to recover from them and on large drives with relatively low reliability specs (most consumer drives are rated at 1 unrecoverable error per 10^14 bits read, which means even odds you can't recover from a drive failure in a 10TB RAID-5 array) you're asking for trouble if this doesn't get done. And it can't get done unless all of the parity information has been initialized.
October 24, 2011 4:03:02 PM

Best answer selected by evlap.
October 24, 2011 4:04:41 PM

Thanks for the in-depth explanation.

Now the big question for me will be to find out if Intel RS implements the background parity checks that you are referring to...
!