• SMB disk IO halts while other disks spin up


    ptr727
    • Minor

    I noticed that existing SMB network IO will halt while a new disk spins up, even if that disk has nothing to do with servicing existing IO requests.

     

    E.g. start a ffmpeg encode session for source and destination media on the SMB network share, wait for other disks to spin down, ffmpeg chugs along, open file explorer and browse around the SMB filesystem, every time you hit a share with disks spun down there will be a delay while the disks will spin up, while the disks are spinning up ffmpeg transcoding halts until the disk is spun up.

     

    Expected behavior is that existing IO is not halted while unrelated disks are spun up that have nothing to do with servicing that IO.




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    Seems highly unlikely that this is a LSI controller issue.

    My guess is the user share fuse code locks all IO while waiting for a disk mount to spin up.

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    On 4/8/2020 at 10:13 AM, JorgeB said:

    This is usually controller related, i.e., some controllers do this, some don't.

    I have the exact issue on my ASRock X570D4U-2L2T and I believe it only started with some unRaid version and I haven’t had the issue before. But I can’t remember when it started. 
    Is there any way to pinpoint if it’s the controller or unRaid?

    Edited by Sledgehamma
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    On 4/8/2020 at 4:48 PM, ptr727 said:

    Seems highly unlikely that this is a LSI controller issue.

    My guess is the user share fuse code locks all IO while waiting for a disk mount to spin up.

     

    My Unraid Servers use LSI/Broadcom 9300-8i and 9300-8e HBAs (latest firmware). User Shares (FUSE) are not activated, only Disk Shares here. The effect happened in all Unraid releases I do remember. Whenever a disk spins up all activity on other disks attached to that same HBA stop for a short time.

     

    Edited by hawihoney
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    On 8/19/2022 at 8:04 PM, hawihoney said:

    Whenever a disk spins up all activity on other disks attached to that same HBA stop for a short time.

    I believe this a restriction built into the hardware (although I could be wrong).

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    3 hours ago, itimpi said:

    I believe this a restriction built into the hardware (although I could be wrong).

     

    Yes, that's what I thought. Think about the "usual" environment for these types of HBA. They are built for disks running all the time.

     

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    best idea is not to use SMB with unraid. SMB on unraid is broken beyond belief, anywhere from 10x to 40,000x slower than a windows server install. 

     

    NFS whilst still significantly slower than a windows server install, will net you something that is usable. 

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