OSDs journal writes and can ACK before writeback finishes. But the
journal is still stable storage. I'm not aware of anything important
that is ACK'd while only in RAM.
On Wed, Dec 7, 2022 at 1:08 PM Charles Hedrick wrote:
>
> I believe asynchronous operations are used for some operations in ceph
POSIX fsync guarantees should hold with cephfs, I guess?
Nathan Fish schrieb am Mi., 7. Dez. 2022, 20:13:
> OSDs journal writes and can ACK before writeback finishes. But the
> journal is still stable storage. I'm not aware of anything important
> that is ACK'd while only in RAM.
>
> On Wed, Dec
Hi Charles,
There are many scenarios where the write/close operation can fail but
generally
failures/errors are logged (normally every time) to help debug the case.
Therefore
there are no silent failures as such except you encountered a very rare
bug.
- Dhairya
On Wed, Dec 7, 2022 at 11:38 PM C
More generally, as Manuel noted you can (and should!) make use of fsync et
al for data safety. Ceph’s async operations are not any different at the
application layer from how data you send to the hard drive can sit around
in volatile caches until a consistency point like fsync is invoked.
-Greg
On
pause until we reboot, and then
continue. However there's an obvious performance penalty for this.
From: Gregory Farnum
Sent: Thursday, December 8, 2022 2:08 AM
To: Dhairya Parmar
Cc: Charles Hedrick ; ceph-users@ceph.io
Subject: Re: [ceph-users] Re: what
: Thursday, December 8, 2022 2:08 AM
> To: Dhairya Parmar
> Cc: Charles Hedrick ; ceph-users@ceph.io <
> ceph-users@ceph.io>
> Subject: Re: [ceph-users] Re: what happens if a server crashes with cephfs?
>
> More generally, as Manuel noted you can (and should!) make use of fsync
ong, the users' jobs pause until we reboot, and
>> then continue. However there's an obvious performance penalty for this.
>> ________________
>> From: Gregory Farnum
>> Sent: Thursday, December 8, 2022 2:08 AM
>> To: Dhairya Parmar
>>
e use NFS. It uses synchronous
>> I/O, so if somethings goes wrong, the users' jobs pause until we reboot, and
>> then continue. However there's an obvious performance penalty for this.
>>
>> From: Gregory Farnum
>> Sent: Thursd
Hedrick
> wrote:
> >>
> >> thanks. I'm evaluating cephfs for a computer science dept. We have
> users that run week-long AI training jobs. They use standard packages,
> which they probably don't want to modify. At the moment we use NFS. It uses
> synchronou
ceph-users@ceph.io
Subject: Re: [ceph-users] Re: what happens if a server crashes with cephfs?
Hi Charles,
are you concerned with a single Ceph cluster server crash or the whole server
crashing? If you have sufficient redundancy, nothing bad should happen but the
file system should remain
Manuel Holtgrewe
> Sent: Thursday, December 8, 2022 12:38 PM
> To: Charles Hedrick
> Cc: Gregory Farnum ; Dhairya Parmar ;
> ceph-users@ceph.io
> Subject: Re: [ceph-users] Re: what happens if a server crashes with cephfs?
>
> Hi Charles,
>
> are you concerned with a singl
From: Manuel Holtgrewe
> Sent: Thursday, December 8, 2022 12:38 PM
> To: Charles Hedrick
> Cc: Gregory Farnum ; Dhairya Parmar ;
> ceph-users@ceph.io
> Subject: Re: [ceph-users] Re: what happens if a server crashes with cephfs?
>
> Hi Charles,
>
> are you concerned with a
Den tors 8 dec. 2022 kl 18:52 skrev Charles Hedrick :
>
> I'm aware that the file system will remain available. My concern is about
> long jobs using it failing because a single operation returns an error. While
> none of the discussion so far has been explicit, I assume this can happen if
> an
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