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dumrat
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Disk performance problems in R720 server

We bought a Dell R720 server and installed CentOS 6.3 on it. We have another older Dell server which also has CentOS 6.3 installed in it. When we ran a simple benchmark for disk performance the older server is 10 times faster for that benchmark as the new one. The benchmark process involves writing something into the disk and flushing it in a loop. We want to track down why this is slow. There are two disks in the new server and we configured them as RAID-0. df -h yields these:

[Older  server]

[xxx@xxx ~]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 97G 28G 64G 31% /
tmpfs 1.9G 11M 1.9G 1% /dev/shm
/dev/sda2 193G 103G 80G 57% /home

[New server]

[xxxx@xxxx ~]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_snap-lv_root 50G 4.6G 43G 10% /
tmpfs 12G 312K 12G 1% /dev/shm
/dev/sda1 485M 37M 423M 9% /boot
/dev/mapper/vg_snap-lv_home 488G 220M 463G 1% /home

 

How to figure out what's making the newer server 10 times slower? How to fix it? Thanks.

Duminda

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Moderator
Moderator

RE: Disk performance problems in R720 server

Hello Duminda

To compare the two systems I will need more information. I will need to know what hardware is used on both systems you are comparing.

What RAID controller?
What model hard disk drives?

Thanks

Daniel Mysinger
Dell EMC, Enterprise Engineer

Get support on Twitter @DellCaresPRO

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dumrat
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RE: Disk performance problems in R720 server

Hi Daniel,

    lshw output:

[Older Server]
[duminda@snapoffice src]$ sudo ./lshw -class storage
[sudo] password for duminda: 
  *-storage               
       description: Serial Attached SCSI controller
       product: SAS2008 PCI-Express Fusion-MPT SAS-2 [Falcon]
       vendor: LSI Logic / Symbios Logic
       physical id: 0
       bus info: pci@0000:05:00.0
       logical name: scsi0
       version: 03
       width: 64 bits
       clock: 33MHz
       capabilities: storage pm pciexpress vpd msi msix bus_master cap_list rom
       configuration: driver=mpt2sas latency=0
       resources: irq:16 ioport:fc00(size=256) memory:df2b0000-df2bffff memory:df2c0000-df2fffff memory:df100000-df1fffff(prefetchable)
  *-ide:0
       description: IDE interface
       product: 5 Series/3400 Series Chipset 4 port SATA IDE Controller
       vendor: Intel Corporation
       physical id: 1f.2
       bus info: pci@0000:00:1f.2
       version: 05
       width: 32 bits
       clock: 66MHz
       capabilities: ide pm bus_master cap_list
       configuration: driver=ata_piix latency=0
       resources: irq:20 ioport:eca0(size=8) ioport:ec90(size=4) ioport:eca8(size=8) ioport:ec94(size=4) ioport:ecc0(size=16) ioport:ecd0(size=16)
  *-ide:1
       description: IDE interface
       product: 5 Series/3400 Series Chipset 2 port SATA IDE Controller
       vendor: Intel Corporation
       physical id: 1f.5
       bus info: pci@0000:00:1f.5
       logical name: scsi3
       version: 05
       width: 32 bits
       clock: 66MHz
       capabilities: ide pm bus_master cap_list emulated
       configuration: driver=ata_piix latency=0
       resources: irq:21 ioport:ecb0(size=8) ioport:ec98(size=4) ioport:ecb8(size=8) ioport:ec9c(size=4) ioport:ece0(size=16) ioport:ecf0(size=16)

[Newer Server]
[root@Snap src]# ./lshw -class storage
  *-storage               
       description: RAID bus controller
       product: MegaRAID SAS 2208 [Thunderbolt]
       vendor: LSI Logic / Symbios Logic
       physical id: 0
       bus info: pci@0000:03:00.0
       logical name: scsi0
       version: 05
       width: 64 bits
       clock: 33MHz
       capabilities: storage pm pciexpress vpd msi msix bus_master cap_list rom
       configuration: driver=megaraid_sas latency=0
       resources: irq:42 ioport:fc00(size=256) memory:ddffc000-ddffffff memory:ddf80000-ddfbffff memory:dd000000-dd01ffff(prefetchable)
  *-storage
       description: SATA controller
       product: C600/X79 series chipset 6-Port SATA AHCI Controller
       vendor: Intel Corporation
       physical id: 1f.2
       bus info: pci@0000:00:1f.2
       logical name: scsi5
       version: 05
       width: 32 bits
       clock: 66MHz
       capabilities: storage msi pm ahci_1.0 bus_master cap_list emulated
       configuration: driver=ahci latency=0
       resources: irq:124 ioport:ece8(size=8) ioport:ecf8(size=4) ioport:ecf0(size=8) ioport:ecfc(size=4) ioport:ecc0(size=32) memory:df8ff000-df8ff7ff


Disk info:

[Older Server]
[duminda@snapoffice ~]$ find /sys/ -type f -name "model"
/sys/devices/pci0000:00/0000:00:05.0/0000:05:00.0/host0/target0:1:0/0:1:0:0/model
/sys/devices/pci0000:00/0000:00:05.0/0000:05:00.0/host0/port-0:0/end_device-0:0/target0:0:0/0:0:0:0/model
/sys/devices/pci0000:00/0000:00:05.0/0000:05:00.0/host0/port-0:1/end_device-0:1/target0:0:1/0:0:1:0/model
/sys/devices/pci0000:00/0000:00:1f.5/host3/target3:0:0/3:0:0:0/model
[duminda@snapoffice ~]$ cat /sys/devices/pci0000:00/0000:00:05.0/0000:05:00.0/host0/target0:1:0/0:1:0:0/model
Virtual Disk    
[duminda@snapoffice ~]$ cat /sys/devices/pci0000:00/0000:00:05.0/0000:05:00.0/host0/port-0:0/end_device-0:0/target0:0:0/0:0:0:0/model
ST500NM0001     
[duminda@snapoffice ~]$ cat /sys/devices/pci0000:00/0000:00:05.0/0000:05:00.0/host0/port-0:1/end_device-0:1/target0:0:1/0:0:1:0/model
ST500NM0001     
[duminda@snapoffice ~]$ cat /sys/devices/pci0000:00/0000:00:1f.5/host3/target3:0:0/3:0:0:0/model
DVD+-RW TS-L633J

googled
ST500NM0001:
 
Storage Capacity: 500 GB
Maximum External Data Transfer Rate: 600 MBps (4.7 Gbps)
Rotational Speed: 7200 rpm
Buffer: 64 MB
Drive Interface: SAS
Drive Interface Standard: 6Gb/s SAS
Drive Type: Internal
Drive Width: 3.5"
Height: 1"
Width: 4"
Depth: 5.8"
Weight (Approximate): 1.34 lb
Limited Warranty: 3 Year
 
[Newer Server]
[root@Snap ~]# find /sys/ -type f -name "model"
/sys/devices/pci0000:00/0000:00:02.2/0000:03:00.0/host0/target0:2:0/0:2:0:0/model
/sys/devices/pci0000:00/0000:00:02.2/0000:03:00.0/host0/target0:2:1/0:2:1:0/model
/sys/devices/pci0000:00/0000:00:1f.2/host5/target5:0:0/5:0:0:0/model
[root@Snap ~]# cat /sys/devices/pci0000:00/0000:00:02.2/0000:03:00.0/host0/target0:2:0/0:2:0:0/model
PERC H710       
[root@Snap ~]# cat /sys/devices/pci0000:00/0000:00:02.2/0000:03:00.0/host0/target0:2:1/0:2:1:0/model
PERC H710       
[root@Snap ~]# cat /sys/devices/pci0000:00/0000:00:1f.2/host5/target5:0:0/5:0:0:0/model
DVD+-RW DS-8A9SH

The quotation says :
300GB  5K RPM, 6Gbps    SAS 3.5" Hot Plug Hard Drive    x2



Please let me know if you need any more information. Thank you.
Duminda
 
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Moderator
Moderator

RE: Disk performance problems in R720 server

It looks like this:

Old server:

PERC 6/i
500GB SATA 7200RPM

New server:

PERC H710
300GB SAS 15000RPM - I'm assuming the 5K RPM is a typo. If it is not a typo then that would be part of the performance problem.

Based on that information The new system should out-perform the old system by a substantial margin. The PERC 6 is a really nice controller, so the H710 is not going to be a LOT better but it should be better. Your big performance gain on the new server is with the 15k drives versus the 7200 RPM SATA drives. The old server should definitely not be 10x faster.

There is one setting on the controller that is disabled by default. It could have a big performance impact. The controller has cache memory, and typically the hard drives also have their own cache memory. By default the controller does not utilize the hard drive cache memory because it is not battery backed. In the event of sudden loss of power you can have data loss/corruption if non-battery backed cache is being utilized. If you have this setting enabled on the old server and disabled on the new server it could explain the benchmark results.

Thanks

Daniel Mysinger
Dell EMC, Enterprise Engineer

Get support on Twitter @DellCaresPRO

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dumrat
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RE: Disk performance problems in R720 server

Hi Daniel,

    We still haven't been able to figure out the issue. About your last paragraph - Where to change these settings? I cannot see them in BIOS. Thanks.

Duminda

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