Date: Tue, 8 Jul 2008 19:25:52 -0700 From: "Jeff Mohler" <speedtoys.racing@gmail.com> To: juri_mian@yahoo.com Cc: freebsd-fs@freebsd.org Subject: Re: 24 TB UFS2 reality check ? Message-ID: <a969fbd10807081925o1ee3b70cn772ca48d3afb393@mail.gmail.com> In-Reply-To: <96359.64292.qm@web45601.mail.sp1.yahoo.com> References: <a969fbd10807081434r1c4e4ed5v1a3771463e9e8d9c@mail.gmail.com> <96359.64292.qm@web45601.mail.sp1.yahoo.com>
next in thread | previous in thread | raw e-mail | index | archive | help
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. Cuz..if you have RAID, and you lose 1 drive, you have to touch a lot of bits to recover that drive, which drives you quickly in to the mathematical region of yet another BER, then you have a double drive failure. Just saying, good luck And even back in 2002, uBER was only a point shorter, and that math was a LOT harder to hit on the much smaller drives/arrays. Let say you go bling for high end SATA drives, you only get about E16 at best, which still isnt good math with a 24TB FS...theoretically. And, not to mention the cubic inches of RAM required to manage it once you start to really fill it, much less fsck it. On Tue, Jul 8, 2008 at 7:04 PM, Juri Mianovich <juri_mian@yahoo.com> wrote: > > > > --- On Tue, 7/8/08, Jeff Mohler <speedtoys.racing@gmail.com> wrote: > > >> Wow..the odds of hitting an uncorrectable bit error are >> actually >> pretty HIGH in that configuration,. >> >> Good luck. >> >> You may get to find out why Enterprise arrays are >> expensive. > > > Can you elaborate ? Why do you say that ? > > Did people say the same thing circa 2002 when the first 1-2TB configurations were being put together with off the shelf parts, or is there something special in particular about >20 TB that I don't understand? > > Thanks. > > > > >
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?a969fbd10807081925o1ee3b70cn772ca48d3afb393>