I'm very curious as to when did harddrive manufacturers swich to having independently operating heads? Is this a new development that I missed? For as long as I can remember, the heads (regardless of how many there are) are operated by a single head motor. So while it can interleave data across multiple platters, all the heads would still be at the same location on the platters.
On Mon, Sep 21, 2009 at 11:09 AM, Alverson, Tom (Xetron) < tom.alver...@ngc.com> wrote: > I'm wondering why they have not done this yet as well. Using more that > 2 heads in parallel would at some point be enough to saturate existing > SATA interfaces. There is no way they could do 8 heads in parallel and > have enough bandwidth (even with 3.0 Gbit/sec SATA) to prevent > saturating the SATA bus. > > "Flash" hard drives have been doing this since the first ones came out > several years ago (running multiple sub-systems in parallel) to overcome > the slower speeds of the Flash chips. I don't know if the modern flash > hard drives need to do this any more (the flash chips might be fast > enough now). The first Flash hard drives ran about $30,000 for a 30GB > drive, and they were in the 3.5 in form factor to fit all the chips. > > Tom > > -----Original Message----- > From: Ben Scott [mailto:mailvor...@gmail.com] > Sent: Thursday, September 17, 2009 8:37 PM > To: NT System Admin Issues > Subject: Hard disk technology (was: Disk based backup) > > On Thu, Sep 17, 2009 at 4:10 PM, Alverson, Tom (Xetron) > <tom.alver...@ngc.com> wrote: > >> Modern hard drives can sustain, what, maybe 0.4 to 0.6 Gbit/sec? > >> Even the 3 Gbit/sec we have now is much higher than that. How is > >> moving to 6 Gbit/sec going to help? :) > > > > All they need to do is upgrade the (on-board) controllers to operate > all > > the heads in parallel. For a 4 platter drive (8 heads) they could get > > an immediate 8X improvement in real read and write speeds. > > But that's got nothing to do with any particular revision of the > SATA standard, right? You can interleave data across heads whether > it's SATA, SCSI, or PATA. Even PATA hard drives have been presenting > synthetic C/H/S geometry for something like a decade now, so it's not > like the controllers don't already have to do the job. > > And given that *current* hard drives can't even keep up with SATA at > 1.5 Gbit/sec, I would then ask: Why haven't they done this already? > Or have they already, and the speeds we see today are *with* > interleaving? > > (I'll ignore for the time being that most consumer hard disks these > days only have one or two heads anyway.) > > -- Ben > > ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ > ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ > > ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ > ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ > > ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~
