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Thread: Hard drive DMA

  1. #1
    Join Date
    Jan 2005
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    Hard drive DMA

    I'm not sure if my hard drive is set to the optimal configuration, it seems to be set on udma33 in WHM > Server information:


    hdc: host protected area => 1
    hdc: 312500000 sectors (160000 MB) w/7936KiB Cache, CHS=19452/255/63, UDMA(33)
    hdd: attached ide-disk driver.


    ran a test in SSH:


    [email protected] [~]# hdparm -t /dev/hdc
    /dev/hdc:
    Timing buffered disk reads: 156 MB in 3.02 seconds = 51.66 MB/sec


    I doubt udma33 can reach over 50 MB/sec. It's a Maxtor 160GB SATA 8mb cache, it's set to UDMA2. Anyone could shed any light on this?

  2. #2
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    that is about right for a parallel ata drive.

  3. #3
    What kind of server is this?

    How about lspci -v output?
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  4. #4
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    Originally posted by TulipSystems
    that is about right for a parallel ata drive.
    This is a serial ATA drive though, shouldn't it go faster??

    It's a quality Dell server courtesy of the folks at allmanaged

  5. #5
    No, 50MB/s is fine for a SATA disk.

    The question is, what are your iowait values?

    Run "top" in one SSH session, while running "hdparm -t /dev/hda" in another SSH, and see if iowait spikes.

    If it does, it's very possible that DMA is not enabled. However, remember, that the physical platter to interface rate is not going to get much faster than 58-59MB/s on an IDE/SATA disk.

    When you start talking about Ultra320 15K SCSI, then you'll see higher numbers. Remember, this is a 7,200RPM disc, not much more you can expect from that.

    If you want to see the speed from buffer to computer, rather than platter to computer, run hdparm -T (capital T)

    Best
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  6. #6
    This sounds like a Dell 750, if so, this is normal. The 160Gb drive sounds familiar, and come to think of it the benchmark is identical to what we get with some 750's we recently picked up from Dell w/the WD1600JB disc.

    Due to high iowait we'll be replacing the SATA discs with SCSI drives. If you are using 2.4 kernel this will also be exxagerated further.
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  7. #7
    /dev/hda:
    Timing buffered disk reads: 100 MB in 1.79 seconds = 55.87 MB/sec


    --

    Dell PowerEdge 750
    Pentium 4 2.8 w/HT, 1MB Cache, 800 FSB
    Standard Dell WD1600JB SATA disc

    This is running RHEL 3 in my office at this time.

    --
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  8. #8
    Join Date
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    Your hard drive is a WD. here is the output from lspci -v

    00:00.0 Host bridge: Intel Corp. 82875P/E7210 Memory Controller Hub (rev 02)
    Flags: bus master, fast devsel, latency 0
    Memory at fe800000 (32-bit, prefetchable) [size=4M]
    Capabilities: [e4] #09 [3106]

    00:03.0 PCI bridge: Intel Corp. 82875P/E7210 Processor to PCI to CSA Bridge (rev 02) (prog-if 00 [Normal decode])
    Flags: bus master, 66Mhz, fast devsel, latency 64
    Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
    I/O behind bridge: 0000e000-0000efff
    Memory behind bridge: fe100000-fe2fffff

    00:1c.0 PCI bridge: Intel Corp. 6300ESB 64-bit PCI-X Bridge (rev 02) (prog-if 00 [Normal decode])
    Flags: bus master, 66Mhz, fast devsel, latency 64
    Bus: primary=00, secondary=02, subordinate=02, sec-latency=64
    Capabilities: [50] PCI-X non-bridge device.

    00:1d.0 USB Controller: Intel Corp. 6300ESB USB Universal Host Controller (rev 02) (prog-if 00 [UHCI])
    Subsystem: Dell: Unknown device 0165
    Flags: bus master, medium devsel, latency 0, IRQ 16
    I/O ports at cce0 [size=32]

    00:1d.1 USB Controller: Intel Corp. 6300ESB USB Universal Host Controller (rev 02) (prog-if 00 [UHCI])
    Subsystem: Dell: Unknown device 0165
    Flags: bus master, medium devsel, latency 0, IRQ 19
    I/O ports at ccc0 [size=32]

    00:1d.4 System peripheral: Intel Corp. 6300ESB Watchdog Timer (rev 02)
    Subsystem: Dell: Unknown device 0165
    Flags: medium devsel
    Memory at fe300400 (32-bit, non-prefetchable) [size=16]

    00:1d.5 PIC: Intel Corp. 6300ESB I/O Advanced Programmable Interrupt Controller (rev 02) (prog-if 20 [IO(X)-APIC])
    Subsystem: Dell: Unknown device 0165
    Flags: bus master, fast devsel, latency 0
    Capabilities: [50] PCI-X non-bridge device.

    00:1d.7 USB Controller: Intel Corp. 6300ESB USB2 Enhanced Host Controller (rev 02) (prog-if 20 [EHCI])
    Subsystem: Dell: Unknown device 0165
    Flags: bus master, medium devsel, latency 0, IRQ 23
    Memory at fe300000 (32-bit, non-prefetchable) [size=1K]
    Capabilities: [50] Power Management version 2
    Capabilities: [58] #0a [2080]

    00:1e.0 PCI bridge: Intel Corp. 82801 PCI Bridge (rev 0a) (prog-if 00 [Normal decode])
    Flags: bus master, fast devsel, latency 0
    Bus: primary=00, secondary=03, subordinate=03, sec-latency=32
    I/O behind bridge: 0000d000-0000dfff
    Memory behind bridge: fc000000-fdffffff

    00:1f.0 ISA bridge: Intel Corp. 6300ESB LPC Interface Controller (rev 02)
    Flags: bus master, medium devsel, latency 0

    00:1f.2 IDE interface: Intel Corp. 6300ESB SATA Storage Controller (rev 02) (prog-if 8a [Master SecP PriP])
    Subsystem: Dell: Unknown device 0165
    Flags: bus master, 66Mhz, medium devsel, latency 0, IRQ 17
    I/O ports at <unassigned>
    I/O ports at <unassigned>
    I/O ports at <unassigned>
    I/O ports at <unassigned>
    I/O ports at fea0 [size=16]

    00:1f.3 SMBus: Intel Corp. 6300ESB SMBus Controller (rev 02)
    Subsystem: Dell: Unknown device 0165
    Flags: medium devsel, IRQ 17
    I/O ports at 08c0 [size=32]

    01:01.0 Ethernet controller: Intel Corp. 82547GI Gigabit Ethernet Controller
    Subsystem: Dell: Unknown device 0165
    Flags: bus master, 66Mhz, medium devsel, latency 0, IRQ 18
    Memory at fe1e0000 (32-bit, non-prefetchable) [size=128K]
    I/O ports at ece0 [size=32]
    Capabilities: [dc] Power Management version 2

    03:02.0 Ethernet controller: Intel Corp. 82541GI/PI Gigabit Ethernet Controller
    Subsystem: Dell: Unknown device 0165
    Flags: bus master, 66Mhz, medium devsel, latency 32, IRQ 21
    Memory at fdee0000 (32-bit, non-prefetchable) [size=128K]
    I/O ports at dcc0 [size=64]
    Capabilities: [dc] Power Management version 2
    Capabilities: [e4] PCI-X non-bridge device.

    03:0e.0 VGA compatible controller: ATI Technologies Inc Rage XL (rev 27) (prog-if 00 [VGA])
    Subsystem: Dell: Unknown device 0165
    Flags: bus master, VGA palette snoop, stepping, medium devsel, latency 32
    Memory at fc000000 (32-bit, non-prefetchable) [size=16M]
    I/O ports at d800 [size=256]
    Memory at fdedf000 (32-bit, non-prefetchable) [size=4K]
    Expansion ROM at <unassigned> [disabled] [size=128K]
    Capabilities: [5c] Power Management version 2

    P4 3.0Ghz 1GB of ram, dual 160GB SATA. Do you know which Dell series is this?

  9. #9
    Yep, this is a Dell PowerEdge 750, 100% positive.

    Good machine, check it out @ www.dell.com

    There is nothing wrong with your hdparm score, 50-60MB/s is normal, if not excellent.

    Remember that the previous generation of Ultra3 SCSI discs would give benchmarks around 40-50MB/s on hdparm.

    (Specifically ST336704LCV, 36.4GB 10K 16MB Cache Ultra160)

    So, overall, it's good

    Enjoy your great server!
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  10. #10
    Join Date
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    Location
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    yeah all of the AM / Sago servers are on 2.4 kernels as they are still using centos 3.3 / 3.4 so you have to deal with the IOWait issues.

    Cpanel just went stable on CentOS4.0 (kernel 2.6) so everyone that upgrades will see a huge improvement in iowait issues.

  11. #11
    Join Date
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    Thanks for those info. I'm really enjoying the server

  12. #12
    Join Date
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    Originally posted by TulipSystems
    yeah all of the AM / Sago servers are on 2.4 kernels as they are still using centos 3.3 / 3.4 so you have to deal with the IOWait issues.

    Cpanel just went stable on CentOS4.0 (kernel 2.6) so everyone that upgrades will see a huge improvement in iowait issues.
    Which Cpanel version is the stable one for CentOS4.0 ? I'm still on 3.4

  13. #13
    Does cPanel work properly on SELinux?
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