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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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