Poor write performance with DELL PERC H700 RAID controller on Red Hat Enterprise Linux 5.3

Solution Verified - Updated -

Issue

We have 3.5 TB of storage (internal harddisk) in the server and we are facing the IO overload on this server.... where the 9th cpu is showing high IO....we are facing the performance issue on this server.

Environment

  • Red Hat Enterprise Linux 5 (RHEL5
    • Observed on kernel-2.6.18-128.el5 (RHEL5.3)
  • Dell R500 Sever
    • Bios version:
      Version: 1.3.6
      Release Date: 05/25/2010
      
    • Local disks are from "DELL PERC H700" RAID controller.  Firmware version 2.30:
      $ less /proc/scsi/scsi
      Host: scsi0 Channel: 02 Id: 00 Lun: 00
        Vendor: DELL     Model: PERC H700        Rev: 2.30
        Type:   Direct-Access                    ANSI SCSI revision: 05
      
    • lspci reports RAID device as unknown:
      $ lspci | grep RAID
      02:00.0 RAID bus controller: LSI Logic / Symbios Logic Unknown device 0079 (rev 04)
      
  • Copying data from EXT3 filesystem on one local disk to an EXT3 filesystem on a separate local disk
    • LVM logical volumes in use on disks.

    • cp command is used

    • File to copy is single 2GB file.

  • Performance of cp is reported as ~80,000 wsec/s in I/O stat, which is approximately 40MB/s:
    Device:         rrqm/s   wrqm/s   r/s   w/s   rsec/s   wsec/s avgrq-sz avgqu-sz   await  svctm  %util
    sdb             148.00     0.00 341.50  0.00 81872.00     0.00   239.74     0.48    1.41   0.81  27.65
    sdc               0.00  9522.00  0.50 192.50     4.00 80552.00   417.39   142.38  738.56   5.18 100.05
    

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