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From: Chris Ridd on 4 May 2010 08:27 On 2010-05-04 12:28:27 +0100, Jaimie Vandenbergh said: > On Tue, 4 May 2010 11:56:19 +0100, Chris Ridd <chrisridd(a)mac.com> > wrote: > >> On 2010-05-04 11:09:11 +0100, Jaimie Vandenbergh said: >> >>> On Tue, 04 May 2010 09:56:52 +0100, David Kennedy >>> <davidkennedy(a)nospamherethankyou.invalid> wrote: >>> >>>> Jaimie Vandenbergh wrote: >>>>> >>>>> Personally I'd go for a WD Blue 500gig, for speed reasons. >>>> >>>> I wondered about that; do you actually notice any difference in use though? >>> >>> It makes VMs work faster, but otherwise not really! You get used to it >>> too quickly. >> >> What aspect of the drive makes it faster than the Samsung? > > Higher data density, which means that for the same spin rate you get > more per second when streaming. Doesn't affect seek time, of course, > so for smaller files no real diff. Ah OK, I was assuming given the same capacity the WD Blue would be faster. > > Samsung M7 400gig are 250gig/platter, two platters, 4 r/w heads. > WB Blue 500gig are 320gig/platter, two platters, 4 r/w heads. > > No, I don't know how that adds up either. I suspect the platter > capacity is a nominal value before block CRCs and reserving spare > blocks, or some such. There's quite a lot of overhead related to the block (sector?) size IIRC, which is one of the reasons behind the introduction of 4K blocks (sectors?). 25%-28% seems quite a lot though given your figures... The efficiency discussion at <http://www.anandtech.com/show/2888> suggests 13% space is needed for the ECC information. > The newer Spinpoint M7E series are 320gig/platter, btw. I thought one difference might be the 320gig platters were using perpendicular (instead of radial?) recording, but that eselleruk page suggested it was using perpendicular recording too. -- Chris
From: Jaimie Vandenbergh on 4 May 2010 09:04
On Tue, 4 May 2010 13:27:05 +0100, Chris Ridd <chrisridd(a)mac.com> wrote: >On 2010-05-04 12:28:27 +0100, Jaimie Vandenbergh said: > >> On Tue, 4 May 2010 11:56:19 +0100, Chris Ridd <chrisridd(a)mac.com> >> wrote: >> >>> On 2010-05-04 11:09:11 +0100, Jaimie Vandenbergh said: >>> >>>> On Tue, 04 May 2010 09:56:52 +0100, David Kennedy >>>> <davidkennedy(a)nospamherethankyou.invalid> wrote: >>>> >>>>> Jaimie Vandenbergh wrote: >>>>>> >>>>>> Personally I'd go for a WD Blue 500gig, for speed reasons. >>>>> >>>>> I wondered about that; do you actually notice any difference in use though? >>>> >>>> It makes VMs work faster, but otherwise not really! You get used to it >>>> too quickly. >>> >>> What aspect of the drive makes it faster than the Samsung? >> >> Higher data density, which means that for the same spin rate you get >> more per second when streaming. Doesn't affect seek time, of course, >> so for smaller files no real diff. > >Ah OK, I was assuming given the same capacity the WD Blue would be faster. Indeed not - the 400gig Blue is 250gig/platter, same as the M7. But the current 320gig blue is 320gig/platter. Only one platter, of course... Which makes the snipped puzzling over platter capacity vs total capacity even odder. I shall proceed to not worry about it! >> Samsung M7 400gig are 250gig/platter, two platters, 4 r/w heads. >> WB Blue 500gig are 320gig/platter, two platters, 4 r/w heads. snip >> The newer Spinpoint M7E series are 320gig/platter, btw. > >I thought one difference might be the 320gig platters were using >perpendicular (instead of radial?) recording, but that eselleruk page >suggested it was using perpendicular recording too. Perpendicular has been the only game in town for several years now, I think the last flat magnetic domains were around the 40gig 3.5" drive sizes. Cheers - Jaimie -- "People can be educated beyond their intelligence" -- Marilyn vos Savant |