Date: Thu, 14 Apr 2005 17:13:48 -0500 From: "Edgar Martinez" <emartinez@crockettint.com> To: "'Nick Pavlica'" <linicks@gmail.com>, "'Benson Wong'" <tummytech@gmail.com> Cc: freebsd-questions@freebsd.org Subject: RE: 5.8TB RAID5 SATA Array Questions Message-ID: <20050414221345.DA71F37AB8@mxc1.crockettint.com> In-Reply-To: <dc9ba04405041412497adcfd59@mail.gmail.com>
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Benson..GREAT RESPONSE!! I Don't think I could have done any better myself. Although I knew most of the information you provided, it was good to know that my knowledge was not very far off. It's also reassuring that I'm not the only nut job building ludicrous systems.. Nick, I believe that we may have some minor misinformation on our hands.. I refer you both to http://www.freebsd.org/projects/bigdisk/ which according to the page. When the UFS filesystem was introduced to BSD in 1982, its use of 32 bit offsets and counters to address the storage was considered to be ahead of its time. Since most fixed-disk storage devices use 512 byte sectors, 32 bits allowed for 2 Terabytes of storage. That was an almost un-imaginable quantity for the time. But now that 250 and 400 Gigabyte disks are available at consumer prices, it's trivial to build a hardware or software based storage array that can exceed 2TB for a few thousand dollars. The UFS2 filesystem was introduced in 2003 as a replacement to the original UFS and provides 64 bit counters and offsets. This allows for files and filesystems to grow to 2^73 bytes (2^64 * 512) in size and hopefully be sufficient for quite a long time. UFS2 largely solved the storage size limits imposed by the filesystem. Unfortunately, many tools and storage mechanisms still use or assume 32 bit values, often keeping FreeBSD limited to 2TB. So theoretically it should go over 1000TB.I've conducted several bastardized installations due to sysinstall not being able to do anything over the 2TB limit by creating the partition ahead of time.I am going to be attacking this tonight and my efforts will be primarily focused on creating one large 5.8TB slice..wish me luck!! PS: Muhaa haa haa! _____ From: Nick Pavlica [mailto:linicks@gmail.com] Sent: Thursday, April 14, 2005 2:49 PM To: Benson Wong Cc: emartinez@crockettint.com; freebsd-questions@freebsd.org Subject: Re: 5.8TB RAID5 SATA Array Questions > Is there any limitations that would prevent a single volume that large? (if > I remember there is a 2TB limit or something) 2TB is the largest for UFS2. 1TB is the largest for UFS1. Is the 2TB limit that you mention only for x86? This file system comparison lists the maximum size to be much larger (http://en.wikipedia.org/wiki/Comparison_of_file_systems). --Nick
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