I have had extremely bad performance historically with onboard SATA chipsets
on Linux. The one exception has been with the Intel based chipsets (not the
CPU, the I/O chipset).
This board has Intel chipset. I cannot remember the exact type but it
was not in the low end category.
dmesg says:
<Intel ICH7 SATA300 controller>
kernel: ad4: 152626MB <SAMSUNG HD160JJ ZM100-33> at ata2-master SATA150
kernel: ad4: 152627MB <SAMSUNG HD160JJ ZM100-33> at ata3-master SATA150
It is very likely that you are having problems with the driver for the
chipset.
Are you running RAID1 in hardware? If so, turn it off and see what the
performance is. The onboard hardware RAID is worse than useless, it
actually slows the I/O down.
I'm using software raid, namely gmirror:
GEOM_MIRROR: Device gm0 created (id=2574033628).
GEOM_MIRROR: Device gm0: provider ad4 detected.
GEOM_MIRROR: Device gm0: provider ad6 detected.
GEOM_MIRROR: Device gm0: provider ad4 activated.
GEOM_MIRROR: Device gm0: provider ad6 activated.
#gmirror list
Geom name: gm0
State: COMPLETE
Components: 2
Balance: round-robin
Slice: 4096
Flags: NONE
GenID: 0
SyncID: 1
ID: 2574033628
Providers:
1. Name: mirror/gm0
Mediasize: 160040803328 (149G)
Sectorsize: 512
Mode: r5w5e6
Consumers:
1. Name: ad4
Mediasize: 160040803840 (149G)
Sectorsize: 512
Mode: r1w1e1
State: ACTIVE
Priority: 0
Flags: DIRTY
GenID: 0
SyncID: 1
ID: 1153981856
2. Name: ad6
Mediasize: 160041885696 (149G)
Sectorsize: 512
Mode: r1w1e1
State: ACTIVE
Priority: 0
Flags: DIRTY
GenID: 0
SyncID: 1
ID: 3520427571
I tried to do:
#sysctl vfs.read_max=32
vfs.read_max: 6 -> 32
but I could not reach better disk read performance.
Thank you for your suggestions. Looks like I need to buy SCSI disks.
Regards,
Laszlo
