maria-discuss team mailing list archive

[Gionatan Danti <g.danti@xxxxxxxxxx>]

On 16/08/2018 23:41, Vladislav Vaintroub wrote:
> I  think it is up to the OS kernel  how to handle interrupt request when 
> a system call is in progress. If kernel reacts to signals/exceptions by 
> interrupting write() call in the middle of copying data from your buffer 
> to the page cache, nothing would help.  And what means “in the middle”, 
> is also unclear. There would be some kind of granularity (page size in 
> pagecache maybe). I do not know what different kernels do in such cases, 
> but this the is level where ZFS is not involved at all.

Well, the manual [1] seems quite explicit about the possibility to have 
write() interrupted by a signal (and, by extension, due to a process crash):

"If a write() is interrupted by a signal handler before any bytes are 
written, then the call fails with the error EINTR; if it is interrupted 
after at least one byte has been written, the call succeeds, and returns 
the number of bytes written."

With such a premise, do you think disabling doublewrite still be safe?
Thanks.

[1] https://linux.die.net/man/2/write

--
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti@xxxxxxxxxx - info@xxxxxxxxxx
GPG public key ID: FF5F32A8