Re: [9fans] Corrupted meta data - Plan9

This is a discussion on Re: [9fans] Corrupted meta data - Plan9 ; > How do you remove a file with corrupted meta data? > I was in 9vx and trying to recompile a kernel so > I could get a boot file with the local method > and it locked. After I ...

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Thread: Re: [9fans] Corrupted meta data

  1. Re: [9fans] Corrupted meta data

    > How do you remove a file with corrupted meta data?
    > I was in 9vx and trying to recompile a kernel so
    > I could get a boot file with the local method
    > and it locked. After I killed 9vx and started it
    > up again, I can't mk because main.8 has corrupted
    > meta data. check in fossilcons reports it, but
    > apparently can't fix it. I also can't remove
    > it in fossilcons any more than I can from an rc
    > prompt.
    >
    > Any magic?


    Can you clri the file from fossilcons?

    Russ



  2. Re: [9fans] Corrupted meta data

    > Can you clri the file from fossilcons?

    Unfortunately, that just reports the corrupted meta data too.
    Interestingly, when I started it up this morning, the check
    didn't report an error with it. But then after trying to
    access it, check now reports:
    error: could not unpack meta block: /active/sys/src/9/pc[3]: corrupted meta data
    What does the 3 refer to? The 3rd block of the pc directory,
    maybe?

    The pc directory itself seems fine. I can see everything
    else there. main.8 doesn't show up in an lc. If my current
    directory is elsewhere and I try to ls -l /n/fossil/sys/src/9/pc/main.8,
    it comes up as not existing. But if my current directory
    is /n/fossil/sys/src/9/pc, then I get the corrupted meta
    data error.

    I haven't changed anything in that directory, so in principle,
    I guess i could blow away the directory (clri if necessary)
    and copy it all back from a venti snapshot. But before I
    do that, I'd like to see if a more direct recovery is possible.

    BTW, I had it lock up again this morning. I've noticed that
    when it does, it uses 100% of the CPU. It's acting like
    it's stuck in a spin lock. I can't say for sure, so this
    may be a red herring, but it has seemed that every time
    it's locked up, it's been when doing I/O to the sdloop
    device.

    Thanks,
    BLS



  3. Re: [9fans] Corrupted meta data

    > error: could not unpack meta block: /active/sys/src/9/pc[3]: corrupted meta data
    > What does the 3 refer to? The 3rd block of the pc directory,
    > maybe?


    Yes.

    Your best bet is probably to clri /active/sys/src/9/pc
    and not look back.

    > BTW, I had it lock up again this morning. I've noticed that
    > when it does, it uses 100% of the CPU. It's acting like
    > it's stuck in a spin lock. I can't say for sure, so this
    > may be a red herring, but it has seemed that every time
    > it's locked up, it's been when doing I/O to the sdloop
    > device.


    Locks on Plan 9 don't use 100% of the cpu.
    Even spin locks start sleeping after enough
    contention.

    It's more likely in a bad loop somewhere.
    Is it repeatedly doing I/O during the 100% cpu?

    Russ



  4. Re: [9fans] Corrupted meta data

    > Your best bet is probably to clri /active/sys/src/9/pc
    > and not look back.


    clri /active/sys/src/9/pc
    no_lb_mode = 1 ;

    It is happy now.

    > It's more likely in a bad loop somewhere.
    > Is it repeatedly doing I/O during the 100% cpu?


    I don't honestly know. Next time it happens, I'll
    check and see.

    BLS



  5. Re: [9fans] Corrupted meta data

    > It's more likely in a bad loop somewhere.
    > Is it repeatedly doing I/O during the 100% cpu?


    It just locked again. Here's what I'm seeing. In
    top, the first thread is using 100% of the CPU and
    all the other threads are in the S state with no run
    time. I don't see any indications either in vmstat
    or in load from p9p that there is any I/O going
    on to speak of or an unusual number of system calls
    being issued. If there's anything else I can
    check, let me know.

    Thanks,
    BLS



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