Hello Justin (& all) ,
On Thu, 28 Jun 2007, Justin Piszcz wrote:
On Thu, 28 Jun 2007, Peter Rabbitson wrote:
Justin Piszcz wrote:
On Thu, 28 Jun 2007, Peter Rabbitson wrote:
Interesting, I came up with the same results (1M chunk being superior)
with a completely different raid set with XFS on top:
...
Could it be attributed to XFS itself?
Peter
Good question, by the way how much cache do the drives have that you are
testing with?
I believe 8MB, but I am not sure I am looking at the right number:
root@Arzamas:~# hdparm -i /dev/sda
/dev/sda:
Model=aMtxro7 2Y050M , FwRev=AY5RH10W,
SerialNo=6YB6Z7E4
Config={ Fixed }
RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4
BuffType=DualPortCache, BuffSize=7936kB, MaxMultSect=16, MultSect=?0?
CurCHS=16383/16/63, CurSects=16514064, 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
AdvancedPM=yes: disabled (255) WriteCache=enabled
Drive conforms to: ATA/ATAPI-7 T13 1532D revision 0: ATA/ATAPI-1
ATA/ATAPI-2 ATA/ATAPI-3 ATA/ATAPI-4 ATA/ATAPI-5 ATA/ATAPI-6 ATA/ATAPI-7
* signifies the current active mode
root@Arzamas:~#
1M chunk consistently delivered best performance with:
o A plain dumb dd run
o bonnie
o two bonnie threads
o iozone with 4 threads
My RA is set at 256 for the drives and 16384 for the array (128k and 8M
respectively)
8MB yup: BuffSize=7936kB.
My read ahead is set to 64 megabytes and 16384 for the stripe_size_cache.
Might you know of a tool for acquiring these (*) parameters for a scsi
drive ? hdrarm really doesn't like real scsi drives so that doesn't seem to work for
me .
(*) "BuffType=DualPortCache, BuffSize=7936kB," Stolen from above .
Tia , JimL
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| James W. Laferriere | System Techniques | Give me VMS |
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