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Obsolete Releases => SME Server 7.x => Topic started by: uniqsys on May 10, 2008, 04:36:44 AM

Title: Hard Drive Capacity
Post by: uniqsys on May 10, 2008, 04:36:44 AM

Hi All,

Just a quick question on hard drive capacity.

I just installed SME 7.3 on an HP ML110 G5 server with two 160 gig hard drives as Raid 1.  All is OK, but I was wondering why the total capacity given by "df -h" is only 145 gig and not closer to 160 gig.  The other 2 partitions use a combined total of 1gig, so that is 14 gig of missing space.  Surely it is not all bad sectors, these are brand new drives.  Can anyone explain that to me?

Thanks.

Title: Re: Hard Drive Capacity
Post by: Marco Hess on May 10, 2008, 04:56:25 AM

145G usable on a 160G hard drive is about right. The 14G remaining is taken up by the file system housekeeping structures (directories, inode tables, journals, etc.).

There is also the classic issue of the size of a KByte (1000 Bytes or 1024 Bytes) with drive manufacturers tending to use the smaller one :-) as you can show more KBytes on a drive, and the operating system tending to use the latter one.

Title: Re: Hard Drive Capacity
Post by: versa on May 10, 2008, 01:16:18 PM

You will also see similar under windows  :P

Your 160gig drive will show up a similar size under windows. Sot it is not just on linux systems

Title: Re: Hard Drive Capacity
Post by: idp_qbn on May 11, 2008, 02:28:29 PM

Hard drive manufacturers cheat:
149Gb (at 1024 bytes per Kb) = 159987531776 bytes (ie approx 160 billion bytes)
Therefore, the manufacturer sells them as "160 Gb". It will show up like this no matter what OS you use....maybe fractional differences since each file system uses a bit for its own housekeeping , as "thf" said.

Cheers
Ian

Title: Re: Hard Drive Capacity
Post by: uniqsys on May 11, 2008, 06:09:47 PM

"I see," said the blind man as he picked up the hammer and saw.  I thank you all for the clarification!  I should have thought it out better.  :oops: