[sf-lug] filesystem for a 3TB external USB drive

[jim]

Thanks for the reply. 

http://www.nexenta.org/  # behaves oddly with my browser 

seems to be a ZFS-based storage appliance with a variety 
of software tools; difficult to read for me, anyway, as 
the description is in a box that disappears to be replaced 
by some other stuff.... yes? 

    the machine I was working with was a supermicro 1U, 
can't remember now exactly its configuration (e.g. I'm 
pretty sure only one power supply rather than a dual 
power supply that's common in enterprise class machines). 




On Sat, 2011-12-31 at 12:53 -0800, Rick Moen wrote:
> Quoting jim (jim at systemateka.com):
> 
> > * In your reply you have a number of references to problems 
> >   with corrupted data due to power failure. 
> >       It seems to me that there are two hardware failure 
> >   points that threaten data: disk drive failure and power 
> >   supply failure. 
> 
> Well, also:
> 
>   [...]
>   What probably hit you here is caused by the very simple fact that
>   PC-class hardware is crap.
> 
>   You see, when you yank the power cord out of the wall, not all parts of
>   the computer stop functioning at the same time. As the voltage starts
>   dropping on the +5 and +12 volt rails, certain parts of the system may
>   last longer than other parts. For example, the DMA controller, hard
>   drive controller, and hard drive unit may continue functioning for
>   several hundred of milliseconds, long after the DIMMs, which are very
>   voltage sensitive, have gone crazy, and are returning total random
>   garbage. If this happens while the filesystem is writing critical
>   sections of the filesystem metadata, well, you get to visit the fun Web
>   pages at http://You.Lose.Hard/ .
> 
>   I was actually told about this by an XFS engineer, who discovered this
>   about the hardware. Their solution was to add a power-fail interrupt and
>   bigger capacitors in the power supplies in SGI hardware; and, in Irix,
>   when the power-fail interrupt triggers, the first thing the OS does is
>   to run around frantically aborting I/O transfers to the disk.
>   Unfortunately, PC-class hardware doesn't have power-fail interrupts.
>   Remember, PC-class hardware is cr*p.
>   [...]
> 
> Much more at http://linuxmafia.com/faq/Filesystems/reiserfs.html
> 
> 
> On the other bit, Jim, when I saw how vaguely you defined your question,
> I decided to kick back and let other people chew up their time on it.
> Attempting to pick a suitable filesystem without knowing the requrements
> is dumb.
> 
> FWIW, if I needed a high degree of data protection and short fsck times
> on a multiterabyte filesystem, I wouldn't go fo zfs-fuse, which is not
> only inherently slow but also is an ugly hack that will never be
> maintainable on account of licence conflict that makes unlawful even any
> distribution of binaries, not to mention merger into mainline.
> 
> So, in that usage case, what I would use instead is Nexenta, which is
> close enough to Debian userspace on a Solaris kernel that I estimate I'd
> feel mostly at home.
> 
> 
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