F20 System Wide Change: No Default Syslog

Zbigniew Jędrzejewski-Szmek zbyszek at in.waw.pl
Fri Jul 19 23:02:00 UTC 2013


On Sat, Jul 20, 2013 at 08:15:11AM +0930, Glen Turner wrote:
> Hi Lennart,
> 
> I suppose someone should mention small flash-disk-only computers.
> 
> There traditionally we fling syslog messages to the serial console or a LRU buffer in RAM (often the dmesg buffer). The point is to avoid I/O on the flash memory. Syslog daemons tend to do a lot of fsync-ed I/O, which just chews up flash write cycles. With some configuration the syslog daemons can be made to not to fsync, and with additional configuration to write to the serial port or to the dmesg ring buffer.
> 
> These small computers aren't specialised embedded systems anymore -- if you buy a cheap ARM-based laptop then you are buying a such a system. Their increasing popularity is very much the reason ARM is becoming a top-teir architecture in Fedora. These systems are *cheap*, so they don't have the write cycles of an expensive SSD.
> 
> I'm not across journald at all. But the questions in my mind are:

I'm not Lennart, but I'll try to answer your questions:

> - Is is possible to run journald without writing to disk; that is: to serial as text, or as binary to a ring buffer which can then by used by journalctl?
Yes, it's possible to keep journal completely in /run/ by setting
Storage=volatile or not creating /var/log/journal at all. See
journald.conf(5).

> - When writing to disk does journald fsync, and if so can that be disabled by a non-guru laptop user?
Yes, see SyncIntervalSec in journald.conf(5).

> - Is journalctl available from the dracut shell, so that we can get bug reports for early system failures? There is a lot more variation in small computers, and thus more early system failures.
Yes, dracut uses systemd and journald too.

> Thank you for making the binary format portable between computers. Allowing a 32b ARM journal file to be displayed on a x86_64 desktop is very useful.
Yes, systemd should be completely portable between architectures.

Zbyszek
-- 
they are not broken. they are refucktored
                           -- alxchk


More information about the devel mailing list