On Thu, Feb 11, 2021 at 12:44 PM Seena Fallah <seenafallah@xxxxxxxxx> wrote:
>
> Many thanks for your response.
> One more question, In the case of a CRC mismatch how many times does it retry and does it raise any error logs in the kernel to see if it had a CRC mismatch or not?
You will see bad "crc/signature" errors in dmesg.
When the session is reset all its state is discarded, so it will retry
indefinitely.
>
> On Thu, Feb 11, 2021 at 3:05 PM Ilya Dryomov <idryomov@xxxxxxxxx> wrote:
>>
>> On Thu, Feb 11, 2021 at 1:34 AM Seena Fallah <seenafallah@xxxxxxxxx> wrote:
>> >
>> > Hi,
>> > I have a few questions about krbd on kernel 4.15
>> >
>> > 1. Does it support msgr v2? (If not which kernel supports msgr v2?)
>>
>> No. Support for msgr2 has been merged into kernel 5.11, due to be
>> released this weekend.
>>
>> Note that the kernel client will only support revision 1 of the msgr2
>> protocol (also referred to as msgr2.1). The original msgr2 protocol has
>> security, integrity and some general robustness issues that made it not
>> conducive to bringing into the kernel.
>>
>> msgr2.1 protocol was implemented in nautilus 14.2.11 and octopus
>> 15.2.5, so if you want e.g. in-transit encryption with krbd, you will
>> need at least those versions on the server side.
>>
>> The original msgr2 protocol is considered deprecated.
>>
>> > 2. If krbd is using msgr v1, does it checksum (CRC) the messages that it
>> > sends to see for example if the write is correct or not? and if it does
>> > checksums, If there were a problem in write how does it react to that? For
>> > example, does it raise I/O Error or retry or...?
>>
>> Yes, it does. In case of a crc mismatch, the messenger will reset the
>> session and the write will be retried automatically.
>>
>> Thanks,
>>
>> Ilya
Thanks,
Ilya
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