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Raid 10 SSD I/O Performance Issue !
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Raid 10 SSD I/O Performance Issue !

RIYADRIYAD Member, Patron Provider
edited March 2016 in Help

Hi

I rented a server , with 4x512GB SSD and did raid 10 .

So I did raid 1 in root directory and raid10 in /home directory .

I am getting only 121 MB/s (Raid1) I/O in root directory and 219 MB/s IO in /home directory (Raid10) , all most same as SATA Drives

The Drives are Samsung 850 Pro .

But on my other servers (SSD) , I do get 600MB/s-950MB/s or even 1.2GB/s IO on Raid 10 .

So , what do you think of this server IO performance ?

ThankYou
RIYAD

Comments

  • Could be aliens. Or many other reasons, hard to judge by the info you provided.

    Thanked by 2zafouhar RIYAD
  • RIYADRIYAD Member, Patron Provider

    what kind of more information I can add to the post, to make things a bit clear ?

  • rds100rds100 Member
    edited March 2016

    What kind of system is it?
    What motherboard?
    Does it have SATA3 ports?
    Does the SATA layer report that the links to the SSDs are running at 6Gbps or 3Gbps speeds?
    Are the partitions you used to create the RAID properly aligned to 4K?
    Are the RAIDs synced, or are they syncing at the moment?
    What else is going on on the system while you are testing it?
    What is the performance of the individual SSDs, without RAID?
    What does SMART report about the SSDs?
    What are you using to test the IO speeds?

  • RIYADRIYAD Member, Patron Provider

    What kind of system is it?

    Linux > CentOS 6.7

    What motherboard?

    Supermicro motherboard-X10SDV-F Series

    Does it have SATA3 ports?

    Does the SATA layer report that the links to the SSDs are running at 6Gbps or 3Gbps speeds?

    ata2: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

    ata3: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

    ata4: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

    ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310)

    Are the partitions you used to create the RAID properly aligned to 4K?

    Are the RAIDs synced, or are they syncing at the moment?

    It was not syncing

    What else is going on on the system while you are testing it?

    Nothing was going on ,

    What is the performance of the individual SSDs, without RAID? What does SMART report about the SSDs?

    For Smart : Device Model: Samsung SSD 850 PRO 512GB

    Serial Number: S250NXAGA02254B

    What are you using to test the IO speeds?

    dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync

    Could not test disk individually with out raid ,

  • cociucociu Member

    rds100 said: Does the SATA layer report that the links to the SSDs are running at 6Gbps or 3Gbps speeds?

    i had the same problems 3 weeks ago and the sata controller had a issue and work only in 3gps

    Thanked by 1RIYAD
  • rds100rds100 Member
    edited March 2016

    RIYAD said: ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310)

    This is a problem, this will slow everything down. Try rebooting / power cycling and see if the problem clears. Also check this SSD's SMART status. Could be a SSD problem or SATA cable problem.

    RIYAD said: Are the partitions you used to create the RAID properly aligned to 4K?

    http://pastebin.com/ziyDUnkw

    please use the command fdisk -u -l /dev/sda
    (and the same for the other SSDs)
    Also why is your /dev/sdd using different partitioning scheme than the rest?

    Thanked by 1RIYAD
  • RIYADRIYAD Member, Patron Provider

    Here is the out put of fdisk -u -l /dev/sda

    pastebin.com/xkShtZJi

    not sure , why the partitioning like that , the partition was done by the Server Company

    I did reboot , still showing ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310)

    I will power off the server and start again , and see the result

    Again , Thank you very much @rds100 for helping :)

  • RIYAD said: Here is the out put of fdisk -u -l /dev/sda

    pastebin.com/xkShtZJi

    Or, these partitions look properly aligned (at 8 sectors / 4K boundary). Check if the other disks are the same. Also i would repartition /dev/sdd to make it like the rest.

  • RIYADRIYAD Member, Patron Provider

    Here the other disk , seems different

  • RIYAD said: Here the other disk , seems different

    http://pastebin.com/14qa8pD4

    By other disk i mean sdb sdc and sdd. sda1 sda2 and sda3 are not "disks".

  • RIYADRIYAD Member, Patron Provider
  • sdb and sdc look OK. I would get rid of the GPT on sdd and repartition it like the others.

  • RIYADRIYAD Member, Patron Provider

    ok , will do that , and see if the performance , improves .

  • RIYADRIYAD Member, Patron Provider

    It turns out that the SATA data and/or power cable connected to /dev/sdd (SATA-0) was defective, this caused the drive out put at 1.5 Gbps.

    The server company has replaced it , how getting 400MB/s IO

    Thank you @rds100 :)

  • cfgguycfgguy Member, Host Rep

    @rds100 Good Stuff

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