From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 7 Mar 2009 09:37:55 -0500 From: William Josephson To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Message-ID: <20090307143755.GB68357@mero.morphisms.net> References: <20090307060057.GA65761@mero.morphisms.net> <6cbc566e63d124cdbc8191a6060c2e6f@quanstro.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6cbc566e63d124cdbc8191a6060c2e6f@quanstro.net> User-Agent: Mutt/1.4.2.3i Subject: Re: [9fans] threads vs forks Topicbox-Message-UUID: b5f3af60-ead4-11e9-9d60-3106f5b1d025 On Sat, Mar 07, 2009 at 08:58:42AM -0500, erik quanstrom wrote: > i think that's why they put them in a 2.5" form factor with a standard > SATA interface. what are you thinking of? No, the reason they do that is for backwards compatibility. > > SSDs are expensive on a $/MB basis compared to disks. The good ones > > not as much as you think. a top-drawer 15k sas drive is on the order > of 300GB and $350+. the intel ssd is only twice as much. if you compare > the drives supported by the big-iron vendors, intel ssd already has cost > parity. The Intel SSD is cheap and slow :-) > > For short-lived data you only need go over the I/O bus twice vs. three > > times for most NVRAMs based on battery-backed DRAM. > > i'm missing something here. what are your assumptions > on how things are connected? also, isn't there an assumption > that you don't want to be writing short-lived data to flash if > possible? Take a gander at the NetApp NAS filers or DataDomain restorers. Things have to go to NVRAM in case of a crash. The DRAM based NVRAMs are typically quite a bit more expensive than flash based ones and so you have less of it. That means more data has to get flushed to disk since it can't live in battery-backed NVRAM permanently.