36.4GB drive formats out to 32.8GB? what am I missing please grep sectors /var/run/dmesg.boot

D. Goss lists at dylangoss.com
Sun Jun 12 21:48:54 GMT 2005

> 36.4pseudomarketblahgigabytes=36400000000 bytes
> 1 real gigabyte is 2^30=1073741824 bytes and that's means your disk  
> has 33.9 real Gigabytes.
> rest are what's used up by inodes and bitmaps.

Thank you Wojciech - this is clear for me now.

> please show the output of
>   grep sectors /var/run/dmesg.boot

da2: 34715MB (71096320 512 byte sectors: 255H 63S/T 4425C)
da0: 17357MB (35548320 512 byte sectors: 255H 63S/T 2212C)
da1: 34715MB (71096640 512 byte sectors: 255H 63S/T 4425C)

The IBM drives I'm playing with are da1 and da2.  Soon they will be  
part of a RAID-5 array with four of these.  da0 will go away as it's  
U160/7200RPM and newer driver on bus are U320/15kRPM.

> In addition to that filesystem building, manufacturer's "formatted"  
> capacity
> is given in decimal so a Gigabyte...
> Then the system, by default reserves 8% of the filesystem for  
> system overfill.

Thanks Jerry also for the explanation.


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