From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.11.6/8.11.6) with ESMTP id j4ELS6O11903 for ; Sat, 14 May 2005 17:28:06 -0400 Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.200]) by mx3.redhat.com (8.12.11/8.12.11) with ESMTP id j4ELS0GE005222 for ; Sat, 14 May 2005 17:28:00 -0400 Received: by wproxy.gmail.com with SMTP id 68so1675073wra for ; Sat, 14 May 2005 14:27:58 -0700 (PDT) Message-ID: <87f94c370505141427e9e1340@mail.gmail.com> Date: Sat, 14 May 2005 17:27:58 -0400 From: Greg Freemyer Subject: Re: [linux-lvm] disk capacity discrepancy: is it 1000 versus 1024? In-Reply-To: Mime-Version: 1.0 Content-Disposition: inline References: Content-Transfer-Encoding: 8bit Reply-To: Greg Freemyer , LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: LVM general discussion and development On 5/14/05, Maurice Volaski wrote: > I originally had a hardware RAID with fourteen 400 GB drives of > usable capacity (Hitachi 7K400) . That's 5600 GB altogether. That's > what both fdisk and df report (filesystem was ext3). > > When I instead created an LVM2 physical volume on the device, I get > just 5.09 TB. > > Is LVM eating several hundreds gigabytes of space or is it the case > that LVM uses terminology in a strict multiply by 1024 fashion versus > everything else, which is multiplying by 1000. In that case, I guess > the drives aren't really 400 GBs. :-( > > However, it appears that parameters passed to LVM commands are > interpreted using x1000, not x1024. > > other keywords: gigabinarybytes, gibibytes, Gi, terabinarybytes, tebibytes, Ti. > -- > > Maurice Volaski, mvolaski@aecom.yu.edu > Computing Support, Rose F. Kennedy Center > Albert Einstein College of Medicine of Yeshiva University As Maurice implies NIST is making an effort (however small) to standardize GB as 1000 * 1000 * 1000 bytes. See http://physics.nist.gov/cuu/Units/binary.html So per NIST: GB = Gigabyte = 1,000 * 1,000 * 1,000 Bytes GiB = Gibibyte = 1,024 * 1,024 * 1,024 Bytes Or for Maurice TB vs. TiB BTW, the difference between TB and TiB is almost 10% so this has a very user observable effect and would explain Maurice's discrepancy. So if I understand Maurice's question, it becomes: "Is LVM reporting TiB units with a TB designation?" Greg -- Greg Freemyer The Norcross Group Forensics for the 21st Century