On Tue, Apr 8, 2014 at 4:05 PM, Randy S <[email protected]> wrote: > Hi, > > yes even if you incorporate the kilo=1024 > example: > I filled in the example below on the site: > RAID Mode: z1 > Disk Size: 3 tb > Quantity of Disks: 10 > > RAID-Z > *Raw Storage: 30.0 TB / 30000.0 GB > *Usable Storage: 24.6 TB / 25145.7 GB > RAID-Z uses one disk for Parity much like RAID5 and requires at least > three drives to be used. > *Usable storage is the actual post-format amount where kilo = 1024, not > 1000 > > If I use the (n-1)formula this would amount to: > (10-1) * 3 TB = 27 TB (27000 GB) > even if you use 1 TB=1024 GB: > (10-1) * 3072 GB = 27.648 GB > > Somewhere theres about 2.5 TB being used for something in their > calculations. > Maybe someone can explain or show me where my calculation is going wrong? >
You've converted the wrong way. Your "3TB" drive is really 3000000000000 bytes or 3TiB. If you correct for the 1024 vs 1000, (with a terabyte, that happens 4 times) you lose ~10%, which is about what you're seeing. > Thanx > > R > > > Date: Tue, 8 Apr 2014 16:32:23 +0200 > > From: [email protected] > > To: [email protected] > > Subject: Re: [OpenIndiana-discuss] Formula raidz storage space > caclulation > > > > Hi, > > > > "Randy S" <[email protected]> írta 2014-04-08 16:16-kor: > > > The information that I have about the formula to use is (n-1) x > storage space per disk > > > n=number of disks > > > 1=is de disk used for parity in a raidz1 configuration. > > > In the case of Raidz2 , this number would be 2 (n-2) x space. > > > > > > My question is: is this formula correct? > > > Reason, my outcome always differs with from the outcome on the > following website: http://www.servethehome.com/raid-calculator/ > > > What would be the correct formula to use? > > > > Did you count in your calculations what the manufacturers cheat on the > > meaning of kilo (1024 vs 1000)? > > They also note that: > > " > > *Usable storage is the actual post-format amount where kilo = 1024, not > > 1000 > > " > > > > Regards, > > György > > > > _______________________________________________ > > OpenIndiana-discuss mailing list > > [email protected] > > http://openindiana.org/mailman/listinfo/openindiana-discuss > > _______________________________________________ > OpenIndiana-discuss mailing list > [email protected] > http://openindiana.org/mailman/listinfo/openindiana-discuss > -- -Peter Tribble http://www.petertribble.co.uk/ - http://ptribble.blogspot.com/ _______________________________________________ OpenIndiana-discuss mailing list [email protected] http://openindiana.org/mailman/listinfo/openindiana-discuss
