Messages in this thread | | | Date | Mon, 26 Jul 2004 21:29:39 +0200 | From | Johannes Stezenbach <> | Subject | Re: max request size 1024KiB by default? |
| |
On Sat, Jul 24, 2004 at 06:58:02PM -0400, Lee Revell wrote: > On Sat, 2004-07-24 at 07:27, Rudo Thomas wrote: > > > HD info: > > > /dev/hdc: > > > > > > Model=Maxtor 6Y160P0, FwRev=YAR41BW0, SerialNo=Y44K8TZE > > > Config={ Fixed } > > > RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=57 > > > BuffType=DualPortCache, BuffSize=7936kB, MaxMultSect=16, MultSect=16 > > > CurCHS=4047/16/255, CurSects=16511760, LBA=yes, LBAsects=268435455 > > > IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} > > > PIO modes: pio0 pio1 pio2 pio3 pio4 > > > DMA modes: mdma0 mdma1 mdma2 > > > UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6 > > > AdvancedPM=yes: disabled (255) WriteCache=enabled > > > Drive conforms to: (null): > > > > Your disk controller must not support that. It looks like the default > is 1024KiB or whatever the max your controller supports is:
For drives smaller than 128GiB the "48-bit Address feature set" is optional, hence many older drives do not support it (since the old 28-bit LBA addressing is suffient).
With 28-bit addressing the number sectors which can be transferred in one request is limited to 256. Linux 2.4 limited this further to 128 (i.e. 64KiB). With 48-bit addressing up to 2^16 sectors could be transferred in one request, but Linux 2.6 puts an arbitrarily chosen limit of 1024KiB on it.
'hdparm -I /dev/hda' will tell you whether your drive supports 48-bit addressing:
Commands/features: Enabled Supported: * 48-bit Address feature set
For full details see the ATA/ATAPI-7 spec at http://www.t13.org/.
Johannes - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |