Date: Thu, 16 Mar 2017 21:47:33 +0100 From: "Martin S. Weber" <ephaeton@gmx.net> To: freebsd-questions@freebsd.org Subject: Re: bootable ext. USB SSD for backup Message-ID: <3c607797-bdae-992e-2783-bb066b15e86d@gmx.net> In-Reply-To: <20170316213722.139560c8@archlinux.localdomain> References: <20170316194612.GA1748@c720-r314251> <33953.128.135.52.6.1489694167.squirrel@cosmo.uchicago.edu> <92024f3c-2ab3-1741-97de-36455ca56b7e@gmx.net> <20170316213722.139560c8@archlinux.localdomain>
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On 03/16/17 21:37, Ralf Mardorf via freebsd-questions wrote: > On Thu, 16 Mar 2017 21:11:53 +0100, Martin S. Weber wrote: >> Toshiba is clearly underselling the disk. > > I don't think so, I suspect that some bytes are reserved to compensate > borked memory locations. > > [rocketmouse@archlinux ~]$ sudo smartctl -a /dev/sda | head -9 > smartctl 6.5 2016-05-07 r4318 > [x86_64-linux-4.9.13-rt12-1-rt-persianrug] (local build) Copyright (C) > 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org > > === START OF INFORMATION SECTION === > Device Model: TOSHIBA-TL100 > Serial Number: Y69B703NKKEU > LU WWN Device Id: 5 00080d c0061b7c8 > Firmware Version: SBFZ10.3 > User Capacity: 240,057,409,536 bytes [240 GB] > > GParted mentions 223.57 GiB * 1024 * 1024 = 234,430,136.32 bytes. > MBR, file system entries might take some space, too. OTOH the complete > capacity shouldn't shrink ;). bc is your friend: 223.57*2^30 (actually GiB, not 1024*1024 which is MiB) 240056459591.68 and compare to your 240057409536 from above. The difference is slightly less than a MiB: scale=3 (240057409536 - 223.57*2^30)/2^20 .905 Can we stop this excursion now? AFAIK the extra bytes which are to be used as reserve aren't actually reported by the drive. Regards
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