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RAID 5 setup question

I have 3x 146.8GB Ultra320 SCSI drives and set them up in PERC as RAID5.  The total amount of storage is less than 2 hard drives combined - is this normal?  If not, how can I correct this?  Is it better to set all 3 up as a span to have more storage, but no fault tolerance?  Disc 3  is the one in question, disc 1 and 2 are 2 146.8GB drives as a single span for more storage.corvette_dell.jpg

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Moderator
Moderator

Re: RAID 5 setup question

Chicago Deep House,

With the 3 drive Raid 5 you will lose 1/3 of the total space to the parity, which puts it at 293.6, the other 20 I would assume are partition/system information or recovery.

Chris Hawk

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DellEMC

Re: RAID 5 setup question

This looks perfectly normal to me. To avoid completely parroting Chris, I'll just say this:

While I would likely leave it alone, you may be able to get a little bit of that space back by making the stripe size smaller. However, this may potentially slow the server down, because it would have to read more stripes at every single read. It would slow down at write time, too. Now, it may not be enough for you to notice, but there is a trade-off in changing the stripe size. It may work better for you, but it may not. 

Some of that space would also be accounted for in gigabyte rounding vs gibibyte counts. I wouldn't expect to be able to reclaim very much of the difference that you're seeing.

#Iwork4Dell
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