Re: PROBLEM: repeatable lockup on RAID-6 with LUKS dm-crypt on NVMe devices when rsyncing many files

[Christian Theune <ct@flyingcircus.io>]

Hi,

> On 15. Aug 2024, at 13:14, Yu Kuai <yukuai1@huaweicloud.com> wrote:
> 
> Hi,
> 
> 在 2024/08/15 18:03, Christian Theune 写道:
>> Hi,
>> small insight: even given my dataset that can reliably trigger this (after around 1.5 hours of rsyncing) it does not trigger on a specific set of files. I’ve deleted the data and started the rsync on a fresh directory (not a fresh filesystem, I can’t delete that as it carries important data) but it doesn’t always get stuck on the same files, even though rsync processes them in a repeatable order.
>> I’m wondering how to generate more insights from that. Maybe keeping a blktrace log might help?
>> It sounds like the specific pattern relies on XFS doing a specific thing there …
>> Wild idea: maybe running the xfstest suite on an in-memory raid 6 setup could reproduce this?
>> I’m guessing that the xfs people do not regularly run their test suite on a layered setup like mine with encryption and software raid?
> 
> That sounds greate.

Alright. I will try that.

>>> @Yu: you mentioned that you might be able to provide me a kernel that produces more error logging to diagnose this? Any chance we could try that route?
> 
> Yes, however, I still need some time to sort out the internal process of
> raid5. I'm quite busy with some other work stuff and I'm familiar with
> raid1/10, but not too much about raid5. :(
> 
> Main idea is to figure out why IO are not dispatched to underlying
> disks.

Sure, thanks - I’m happy to be patient. :)

Christian

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