Disk saturation

[Carlos H. Reimer]

Hi,

Our database server is getting some very high response times and I´m trying
to understand if the disk configuration is responsible for this issue.

It is a Fedora Core release 4 (Stentz) box with 4 GB RAM and 2 GenuineIntel
XEON CPU 3.20 GHz Cache: 1024 KB.

Some typical iostat -x data:
cpu-moy:  %user   %nice    %sys %iowait   %idle
          11,96    0,00    7,04    1,31   79,70

Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s
avgrq-sz avgqu-sz   await  svctm  %util
sda          0,00  30,44  0,81  3,43   14,52  270,97     7,26   135,48
67,43     0,19   46,05   7,29   3,08

cpu-moy:  %user   %nice    %sys %iowait   %idle
          12,26    0,00    7,34    6,63   73,77

Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s
avgrq-sz avgqu-sz   await  svctm  %util
sda          0,00  32,26  0,00  4,41    0,00  293,39     0,00   146,69
66,55     1,51  342,32  25,14  11,08

cpu-moy:  %user   %nice    %sys %iowait   %idle
          13,67    0,00    6,83    7,74   71,76

Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s
avgrq-sz avgqu-sz   await  svctm  %util
sda          0,00  31,99  0,00  3,82    0,00  286,52     0,00   143,26
74,95     2,93  767,58  55,84  21,35

cpu-moy:  %user   %nice    %sys %iowait   %idle
          13,27    0,00    6,83   14,37   65,53

Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s
avgrq-sz avgqu-sz   await  svctm  %util
sda          0,00  31,73  0,00  4,02    0,00  285,94     0,00   142,97
71,20     2,73  680,40  49,25  19,78

cpu-moy:  %user   %nice    %sys %iowait   %idle
          12,86    0,00    6,33    9,45   71,36

Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s
avgrq-sz avgqu-sz   await  svctm  %util
sda          0,00  30,92  0,00  3,41    0,00  274,70     0,00   137,35
80,47     2,33  681,35  57,53  19,64

cpu-moy:  %user   %nice    %sys %iowait   %idle
          12,45    0,00    6,02    1,91   79,62

Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s
avgrq-sz avgqu-sz   await  svctm  %util
sda          0,00  33,00  0,60  4,23    6,44  297,79     3,22   148,89
63,00     0,41   85,29  20,00   9,66

Is it normal have the %util column showing a saturation of 20% with only
140wKB/s?

How can I be sure if there is a hardware or software raid running over the
disks? I think it is hardware because there is no mdadm process running, am
I right?

Some dmesg data:
SCSI subsystem initialized
Fusion MPT base driver 3.01.20
Copyright (c) 1999-2004 LSI Logic Corporation
ACPI: PCI Interrupt 0000:02:04.0[A] -> GSI 42 (level, low) -> IRQ 185
mptbase: Initiating ioc0 bringup
ioc0: 53C1030: Capabilities={Initiator,Target}
Fusion MPT SCSI Host driver 3.01.20
scsi0 : ioc0: LSI53C1030, FwRev=01032300h, Ports=1, MaxQ=255, IRQ=185
input: AT Translated Set 2 keyboard on isa0060/serio0
input: AT Translated Set 2 keyboard on isa0060/serio0
megaraid cmm: 2.20.2.5 (Release Date: Fri Jan 21 00:01:03 EST 2005)
megaraid: 2.20.4.5 (Release Date: Thu Feb 03 12:27:22 EST 2005)
megaraid: probe new device 0x1000:0x1960:0x1028:0x0520: bus 2:slot 5:func 0
ACPI: PCI Interrupt 0000:02:05.0[A] -> GSI 37 (level, low) -> IRQ 193
megaraid: fw version:[351S] bios version:[1.10]
scsi1 : LSI Logic MegaRAID driver
scsi[1]: scanning scsi channel 0 [Phy 0] for non-raid devices
  Vendor: SDR       Model: GEM318P           Rev: 1
  Type:   Processor                          ANSI SCSI revision: 02
scsi[1]: scanning scsi channel 1 [virtual] for logical drives
  Vendor: MegaRAID  Model: LD 0 RAID1   69G  Rev: 351S
  Type:   Direct-Access                      ANSI SCSI revision: 02
SCSI device sda: 143114240 512-byte hdwr sectors (73274 MB)
sda: asking for cache data failed
sda: assuming drive cache: write through
SCSI device sda: 143114240 512-byte hdwr sectors (73274 MB)
sda: asking for cache data failed
sda: assuming drive cache: write through
 sda: sda1 sda2 sda3 sda4 < sda5 >
Attached scsi disk sda at scsi1, channel 1, id 0, lun 0
libata version 1.10 loaded.
ata_piix version 1.03
ACPI: PCI Interrupt 0000:00:1f.2[A] -> GSI 18 (level, low) -> IRQ 177
PCI: Setting latency timer of device 0000:00:1f.2 to 64
ata1: SATA max UDMA/133 cmd 0xBC98 ctl 0xBC92 bmdma 0xBC60 irq 177
ata2: SATA max UDMA/133 cmd 0xBC80 ctl 0xBC7A bmdma 0xBC68 irq 177
ata1: SATA port has no device.
scsi2 : ata_piix
ata2: SATA port has no device.
scsi3 : ata_piix
isa bounce pool size: 16 pages
kjournald starting.  Commit interval 5 seconds
EXT3-fs: mounted filesystem with ordered data mode.
SELinux:  Disabled at runtime.
SELinux:  Unregistering netfilter hooks
cfq: depth 4 reached, tagging now on
Attached scsi generic sg0 at scsi1, channel 0, id 6, lun 0,  type 3
Attached scsi generic sg1 at scsi1, channel 1, id 0, lun 0,  type 0
Floppy drive(s): fd0 is 1.44M

Thank you in advance!

Reimer