Date: Sun, 5 Jun 2005 15:10:35 -0700 From: "D. Goss" <lists@dylangoss.com> To: freebsd-questions@freebsd.org Subject: Re: 36.4GB drive formats out to 32.8GB? what am I missing please Message-ID: <15943E92-74D1-4D79-B285-0D6863DA9572@dylangoss.com> In-Reply-To: <42A35971.9030101@cloudview.com> References: <3A0E3262-4941-48F5-9532-5E45359690F1@dylangoss.com> <42A35971.9030101@cloudview.com>
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>> I am adding some drives to an IBM xSeries 345. I recently picked up >> (via eBay) an IBM packaged Seagate drive, all with the proper IBM >> part numbers as: >> >> U320 15k >> 36.4GB formatted capacity >> (IBM part 06P5776 / 06P5778, with Seagate drive ST336753LC) >> >> Looking up both the IBM part numbers and the Seagate part numbers via >> Google, I consistantly get that the drive's formatted capacity is >> 36.4GB. >> >> When partitioned either in "safe" or "dd" mode (via sysinstall) and >> set to use the entire disk as one slice, once the drive is mounted I >> show: >> >> # df -m >> /dev/da1s1 33617 0 30928 0% /misc >> >> # df -h >> /dev/da1s1 33G 4.0K 30G 0% /misc >> >> I'm seeing approx. 30,600MB (32.8GB?) free - >> >> >> > I suspect three things are goping on > > 1) disk makers specify GB as 1,000,000,000 bytes but everybody else > specifies 1,073,741,824 bytes (1024*1024*1024) this will yeild 33.9 GB > from your 36.4 GB drive I have always seen drives format out at less but the thing that threw me was that 36.4 was listed as "formatted capacity" - by IBM (not Seagate). This helps though. Somehow this reminds me of the # of hotdogs in a pack vs. # of buns. > 2) formatting itself takes some space for superblocks etc > Figured, but not much, right? > 3) some psace is reserved (man newfs and tunefs for info) > Read those man pages and that helped a lot. I have read this before and it wasn't retained. 8% is the kind of loss I was looking for. Thanks for all the quick answers. d.
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