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
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