[Ubuntu] After deployment sends data with wrong disks format

[Evgeniy L]

From https://bugs.launchpad.net/fuel/+bug/1262973

The problem is after deployment changed disks naming

Before deployment it looked good
[
    {
        "disk": "disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0",
        "model": "ST3160815AS",
        "size": 160041885696,
        "name": "sda"
    },
    {
        "disk": "disk/by-path/pci-0000:00:1f.2-scsi-2:0:0:0",
        "model": "ST2000DM001-1CH1",
        "size": 2000398934016,
        "name": "sdc"
    },
    {
        "disk": "disk/by-path/pci-0000:00:1f.2-scsi-1:0:0:0",
        "model": "ST2000DM001-1CH1",
        "size": 2000398934016,
        "name": "sdb"
    }
]

But after deployment format was changed

[
    {
        "model": "ST2000DM001-1CH1",
        "disk": "sdc",
        "size": 2000398934016,
        "name": "sdc"
    },
    {
        "model": "ST2000DM001-1CH1",
        "disk": "sdb",
        "size": 2000398934016,
        "name": "sdb"
    },
    {
        "model": "ST3160815AS",
        "disk": "disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0",
        "size": 160041885696,
        "name": "sda"
    }
]

We use `disk` as uniq disk identificator in nailgun.
Name like sdb\sdc in `disk` field use in case if disk wasn't found in /dev/disk/by-path
See https://github.com/stackforge/fuel-web/blob/master/bin/agent#L249-L253

[Andrey Korolyov (xdeller)]

xdeller@ubuntuprecise:/sys$ find . -name vda
./devices/pci0000:00/0000:00:05.0/virtio2/block/vda
./block/vda
./class/block/vda

Useful subfiles are:
size
vendor(available only under address-based path: /sys/devices/pci0000:00/0000:00:03.0/virtio0/vendor)

As I mentioned we can use sysfs-based discovery. Is there any additional hints which may be useful for implementation?

[Mike Scherbakov (mihgen)]

What is the user impact here?

[Evgeniy L (rustyrobot)]

User impact is an user would see wrong disks mapping on UI, I guess.

[Anastasia Palkina (apalkina)]

Reproduced on ISO #108
"build_id": "2014-02-10_01-17-30", "ostf_sha": "d15d6b5b952e455e3afff383413ffa6d89ee7981", "build_number": "108", "nailgun_sha": "da98419023973c10b73aec73fe0d476936f3f662", "fuelmain_sha": "981c07d7a8791a137db636fc7eafc7d22e4f06ea", "astute_sha": "d002c3bf626cff96a1d4aec9eb92fc4d5f4542c4", "release": "4.1", "fuellib_sha": "81ba00fc10375f992f92cb755a9bfa87cfa79755"

1. Create new environment (Ubuntu, HA mode)
2. Choose GRE segmentation
3. Add 3 controllers and 2 compute nodes
4. Nodes had 3 disks before deployment
5. Start deployment. It was successful
6. But nodes has 1 disk after deployment

    "mac": "08:00:27:C0:7F:9D",
    "platform_name": null,
    "meta": {
        "disks": [
            {
                "model": "VBOX HARDDISK",
                "size": 68718428160,
                "name": "sdc",
                "disk": "disk/by-path/pci-0000:00:0d.0-scsi-0:0:0:0"
            }
        ],

root@node-20:~# ls /dev/disk/by-path/
pci-0000:00:0d.0-scsi-0:0:0:0 pci-0000:00:0d.0-scsi-0:0:0:0-part2 pci-0000:00:0d.0-scsi-0:0:0:0-part4
pci-0000:00:0d.0-scsi-0:0:0:0-part1 pci-0000:00:0d.0-scsi-0:0:0:0-part3 pci-0000:00:0d.0-scsi-0:0:0:0-part5

[Vladimir Kozhukalov (kozhukalov)]

This bug appears because Ubuntu kernel maps all hard drives on Vbox in one address (sysfs PATH_ID). When udev daemon creates by-path links it rewrites former links with new ones. So we have just one by-path link for sdc hard drive. We discussed this situation for a while and the only solution is to make our own proprietary links based on some combination of those sysfs variables which are available.

[Vladimir Kozhukalov (kozhukalov)]

Blueprint for this issue

https://blueprints.launchpad.net/fuel/+spec/reliable-disk-naming

[Vladimir Kozhukalov (kozhukalov)]

At the moment we have reliable enough mechanism how to identify disks. We use a combination of by-id and by-path links. by-id links we store in disk extra field. So, despite the fact that Vbox maps all disks in one by-path link, we are still able to identify links if necessary.

[Vladimir Kozhukalov (kozhukalov)]

fix is here https://review.openstack.org/#/c/71885

[Meg McRoberts (dreidellhasa)]

Added to "Fixed Issues" in 5.0 Release Notes