Osma Ahvenlampi wrote:
>
> Jan Edler <[EMAIL PROTECTED]> writes:
> > > Sustained? How are you measuring? The ST317242A's are rated at a
> > > fairly typical 8.5 MBytes/sec sustained. Your numbers are pretty good.
> > measurements is a lack of repeatability. I see about 10% variation from
> > run to run. For the ST317242A, Seagate simply claims >8.5MB/s.
>
> http://www.seagate.com/support/disc/specs/st317242a.shtml says
> internal transfer rate is up to 188 Mbits/sec, ie 23.5MB/s. This would
> be on the outer tracks, and the inner tracks would be about third of
> the speed, as in around 8.5MB/s. Average transfer rate would indeed
> make 60MB/s over 6 drives quite a reachable goal, but not something
> you can rely on in all situations.
Internal transfer rate is a platter to cache measurement. External
transfer rate is cache to EIDE interface, also known as burst rate.
Neither has much to do with real world data transfers.
Take any drive and divide it up evenly into 6-8 partitions. Perform a
simple dd(1) or hdparm(8) read test from each and watch the sustained
speed drop by about 20% from the outside to the inside most partition.
It's a 5400 RPM drive and will not deliver more than ~10MB/s.
[tim@asus tim]# fdisk -l
Disk /dev/hda: 255 heads, 63 sectors, 1021 cylinders
Units = cylinders of 16065 * 512 bytes
Device Boot Start End Blocks Id System
/dev/hda1 * 1 62 497983+ 6 DOS 16-bit >=32M
/dev/hda2 63 1021 7703167+ 5 Extended
/dev/hda5 * 63 68 48163+ 83 Linux native
/dev/hda6 69 170 819283+ 6 DOS 16-bit >=32M
/dev/hda7 171 178 64228+ 6 DOS 16-bit >=32M
/dev/hda8 179 433 2048256 6 DOS 16-bit >=32M
/dev/hda9 434 688 2048256 6 DOS 16-bit >=32M
/dev/hda10 689 693 40131 82 Linux swap
/dev/hda11 694 834 1132551 83 Linux native
/dev/hda12 835 873 313236 83 Linux native
/dev/hda13 874 924 409626 83 Linux native
/dev/hda14 925 1021 779121 83 Linux native
[tim@asus tim]# hdparm -tT /dev/hda{5,11,14,14,11,5}
/dev/hda5:
Timing buffer-cache reads: 64 MB in 0.58 seconds =110.34 MB/sec
Timing buffered disk reads: 32 MB in 2.88 seconds =11.11 MB/sec
/dev/hda11:
Timing buffer-cache reads: 64 MB in 0.54 seconds =118.52 MB/sec
Timing buffered disk reads: 32 MB in 3.37 seconds = 9.50 MB/sec
/dev/hda14:
Timing buffer-cache reads: 64 MB in 0.53 seconds =120.75 MB/sec
Timing buffered disk reads: 32 MB in 3.81 seconds = 8.40 MB/sec
/dev/hda14:
Timing buffer-cache reads: 64 MB in 0.62 seconds =103.23 MB/sec
Timing buffered disk reads: 32 MB in 3.81 seconds = 8.40 MB/sec
/dev/hda11:
Timing buffer-cache reads: 64 MB in 0.71 seconds =90.14 MB/sec
Timing buffered disk reads: 32 MB in 3.39 seconds = 9.44 MB/sec
/dev/hda5:
Timing buffer-cache reads: 64 MB in 0.83 seconds =77.11 MB/sec
Timing buffered disk reads: 32 MB in 2.87 seconds =11.15 MB/sec
[tim@asus tim]# hdparm -i /dev/hda
/dev/hda:
Model=Maxtor 88400D8, FwRev=NAVX171F, SerialNo=L80EEP7A
Config={ Fixed }
RawCHS=16278/16/63, TrkSize=0, SectSize=0, ECCbytes=20
BuffType=3(DualPortCache), BuffSize=256kB, MaxMultSect=16, MultSect=off
DblWordIO=no, maxPIO=2(fast), DMA=yes, maxDMA=2(fast)
CurCHS=1021/255/63, CurSects=16408224, LBA=yes, LBAsects=16408224
tDMA={min:120,rec:120}, DMA modes: mword0 mword1 mword2
IORDY=on/off, tPIO={min:120,w/IORDY:120}, PIO modes: mode3 mode4
--
timothymoore "Everything is permitted. Nothing is forbidden."
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