MFC r267667:
use .Mt to mark up email addresses consistently (part1)

PR: 191174
Submitted by: Franco Fichtner <franco at lastsummer.de>

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

- Add support for 'memsync' mode. This is the fastest replication mode that's
why it will now be the default.
- Bump protocol version to 2 and add backward compatibility for version 1.
- Allow to specify hosts by kern.hostid as well (in addition to hostname and
kern.hostuuid) in configuration file.

Sponsored by: Panzura
Tested by: trociny

Metaflush on/off values don't need quotes.

Reviewed by: pjd
MFC after: 3 days

General mdoc(7) and typo fixes.

PR: 167804
Submitted by: Nobuyuki Koganemaru (kogane!jp.freebsd.org)
MFC after: 3 days

- Fix documentation to note that /etc/hast.conf is the default configuration
file for hastd(8) and hastctl(8) and not hast.conf.
- In copyright statement correct that this file is documentation, not software.
- Bump date.

MFC after: 3 days

Implement 'async' mode for HAST.

MFC after: 3 days

Allow to specify pidfile in HAST configuration file.

MFC after: 1 week

After every activemap change flush disk's write cache, so that write
reordering won't make the actual write to be committed before marking
the coresponding extent as dirty.

It can be disabled in configuration file.

If BIO_FLUSH is not supported by the underlying file system we log a warning
and never send BIO_FLUSH again to that GEOM provider.

MFC after: 3 days

Document IPv6 support.

MFC after: 3 weeks

In preparation for IPv6 support allow to specify multiple addresses to
listen on.

MFC after: 3 weeks

Increase default timeout from 5 seconds to 20 seconds. 5 seconds is definitely
to short under heavy load and I was experiencing those timeouts in my recent
tests.

MFC after: 1 week

In hast.conf we define the other node's address in 'remote' variable.
This way we know how to connect to secondary node when we are primary.
The same variable is used by the secondary node - it only accepts
connections from the address stored in 'remote' variable.
In cluster configurations it is common that each node has its individual
IP address and there is one addtional shared IP address which is assigned
to primary node. It seems it is possible that if the shared IP address is
from the same network as the individual IP address it might be choosen by
the kernel as a source address for connection with the secondary node.
Such connection will be rejected by secondary, as it doesn't come from
primary node individual IP.

Add 'source' variable that allows to specify source IP address we want to
bind to before connecting to the secondary node.

MFC after: 1 week

Allow to compress on-the-wire data using two algorithms:
- HOLE - it simply turns all-zero blocks into few bytes header;
it is extremely fast, so it is turned on by default;
it is mostly intended to speed up initial synchronization
where we expect many zeros;
- LZF - very fast algorithm by Marc Alexander Lehmann, which shows
very decent compression ratio and has BSD license.

MFC after: 2 weeks

Allow to checksum on-the-wire data using either CRC32 or SHA256.

MFC after: 2 weeks

Execute hook when connection between the nodes is established or lost.

MFC after: 2 weeks
Obtained from: Wheel Systems Sp. z o.o. http://www.wheelsystems.com

Execute hook when split-brain is detected.

MFC after: 2 weeks
Obtained from: Wheel Systems Sp. z o.o. http://www.wheelsystems.com

- Call hook on role change.
- Document new event.

MFC after: 2 weeks
Obtained from: Wheel Systems Sp. z o.o. http://www.wheelsystems.com

Document new 'exec' parameter.

MFC after: 2 weeks
Obtained from: Wheel Systems Sp. z o.o. http://www.wheelsystems.com

Fix typos, spelling, formatting and mdoc mistakes found by Nobuyuki while
translating these manual pages. Minor corrections by me.

Submitted by: Nobuyuki Koganemaru <n-kogane@syd.odn.ne.jp>

Document 'none' value for remote.

Reviewed by: dougb
MFC after: 1 month

Spelling fixes.

Actually, only the fullsync mode is implemented, not memsync mode.
Correct manual page.

MFC after: 3 days

mdoc: move remaining sections into consistent order

This pertains mostly to FILES, HISTORY, EXIT STATUS and AUTHORS sections.

Found by: mdocml lint run
Reviewed by: ru

Fix a problem where hastd will stuck in recv(2) after sending request to
secondary, which died between send(2) and recv(2). Do it by adding timeout
to recv(2) for primary incoming and outgoing sockets and secondary outgoing
socket.

Reported by: Mikolaj Golub <to.my.trociny@gmail.com>
Tested by: Mikolaj Golub <to.my.trociny@gmail.com>
MFC after: 3 days

Please welcome HAST - Highly Avalable Storage.

HAST allows to transparently store data on two physically separated machines
connected over the TCP/IP network. HAST works in Primary-Secondary
(Master-Backup, Master-Slave) configuration, which means that only one of the
cluster nodes can be active at any given time. Only Primary node is able to
handle I/O requests to HAST-managed devices. Currently HAST is limited to two
cluster nodes in total.

HAST operates on block level - it provides disk-like devices in /dev/hast/
directory for use by file systems and/or applications. Working on block level
makes it transparent for file systems and applications. There in no difference
between using HAST-provided device and raw disk, partition, etc. All of them
are just regular GEOM providers in FreeBSD.

For more information please consult hastd(8), hastctl(8) and hast.conf(5)
manual pages, as well as http://wiki.FreeBSD.org/HAST.

Sponsored by: FreeBSD Foundation
Sponsored by: OMCnet Internet Service GmbH
Sponsored by: TransIP BV