5.8TB RAID5 SATA Array Questions

Benson Wong tummytech at gmail.com
Thu Apr 14 16:24:24 PDT 2005


Ahh, that clarifies some things. 
UFS2 can handle 2^64, but disklabel, newfs might not be able to yet.
Not entirely sure where things are still 32-bit, I do know that when I
tried to create a 2.2TB file system with the standard freebsd tools it
didn't work.

Ben.

On 4/14/05, Edgar Martinez <emartinez at crockettint.com> wrote:
>  
>  
> 
> 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 at gmail.com] 
>  Sent: Thursday, April 14, 2005 2:49 PM
>  To: Benson Wong
>  Cc: emartinez at crockettint.com; freebsd-questions at 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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