Change in ovirt-hosted-engine-ha[master]: Add metadata storage support for raw block device

[msivak at redhat.com]

Martin Sivák has submitted this change and it was merged.

Change subject: Add metadata storage support for raw block device
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Add metadata storage support for raw block device

This adds support for using raw partition or drive as the metadata
storage device. It implements partitioning schema to support
multiple metadata files and also allows for future extension.

Once the backend is connected to, it uses device mapper interface
to create the devices for all registered metadata files.

The underlying block device uses the following block based
structure. The first block on the device is meta block.

Each meta block (512B) contains:

4B signature (HEs0)
8B index of next meta block or 0 if this is the last one
64 bytes with service name (first byte equals the used length)
8B + 8B pointers to data section (start block, length)
... more data sections if needed
16B of 0 acting as a sentinel
4B CRC32 checksum

If there is need to use lots of data sections for a single service,
is is possible tp use the service name multiple times and the data
blocks will be concatenated using device mapper.

Change-Id: Id6ab21fb2075fc59b444b5754ade8a1569b83b18
Signed-off-by: Martin Sivak <msivak at redhat.com>
---
M ovirt_hosted_engine_ha/lib/storage_backends.py
M ovirt_hosted_engine_ha/lib/storage_backends_test.py
2 files changed, 511 insertions(+), 0 deletions(-)

Approvals:
  Martin Sivák: Verified; Looks good to me, approved
  Greg Padgett: Looks good to me, but someone else must approve



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Gerrit-MessageType: merged
Gerrit-Change-Id: Id6ab21fb2075fc59b444b5754ade8a1569b83b18
Gerrit-PatchSet: 15
Gerrit-Project: ovirt-hosted-engine-ha
Gerrit-Branch: master
Gerrit-Owner: Martin Sivák <msivak at redhat.com>
Gerrit-Reviewer: Doron Fediuck <dfediuck at redhat.com>
Gerrit-Reviewer: Greg Padgett <gpadgett at redhat.com>
Gerrit-Reviewer: Jiří Moskovčák <jmoskovc at redhat.com>
Gerrit-Reviewer: Martin Sivák <msivak at redhat.com>
Gerrit-Reviewer: Sandro Bonazzola <sbonazzo at redhat.com>
Gerrit-Reviewer: automation at ovirt.org
Gerrit-Reviewer: oVirt Jenkins CI Server