24 TB UFS2 reality check ?

[Alexandre Biancalana]

On 7/9/08, Juri Mianovich <juri_mian at yahoo.com> wrote:
>
>  Hello Jeff,
>
>
>  --- On Tue, 7/8/08, Jeff Mohler <speedtoys.racing at gmail.com> wrote:
>
>
>
> > One drive has a what..maybe a 1 per 1.0 E15 bits transferred
>  > uBER, and
>  > you have 24x that of one drive, as each drive it it's
>  > statistical crap
>  > shoot.   Each drive may NEVER hit uBER for you, but one may
>  > do it
>  > tomorrow.
>  >
>  > Plus, you have commodity firmware levels on those drives
>  > and commodity
>  > BER mechanisms, so you COULD argue you have another 2x
>  > liability WRT
>  > losing it all without HEFTY raid, at least 5+1.
>
>
>
> Thank you - I understand.  You are worried because of the lack of redundancy.
>
>  I didn't want to make my questions any more complicated than they were, but since we are on the topic, I will tell you that _in reality_ I will not make a 24 TB array, I will in fact use the raid-6 functionality (two parity drives) of my card and make a ~22 TB array.
>
>  Does that address the concerns you were raising ?  Does 22 data and 2 parity (raid 6) still make you very nervous, or does that completely change the scenario you were worried about ?


I did be fewer nervous if you do 2 arrays of 11 disks... what`s the
time that it will take to do a rebuild of a failed drive in your
normal load ??