[pve-devel] [PATCH] Add generic multipath storage plugin and Netapp module for it

[Dmitry Petuhov]

New version of patch for multipath-backed storage.

Additional Debian packages required: multipath-tools, scsitools.

Multipath devices are being added|deleted in [de]activate_storage().

Backing scsi devices ("paths") are being updated on activate_storage()
and free_image(). This makes these operations little slow and noisy
because of usage of scsitools's rescan-scsi-bus. It uses outdated
kernel interfaces and we could replace it with some newer cool tool
if had one.

As for Netapp module, it is based on Alexandre DERUMIER's plugin for
NFS-backed Netapp NAS and extended to manipulate LUNs and to support
older '7-mode' devices.

My testing storage.cfg:
======================
mpdirect: netappdirect
        content images
        adminserver 10.13.x.y
        login root
        password ***
        array aggr_vm
        api 7
        igroup pve-test
        backend netapp
        media iscsi
======================
Where `array' -- RAID array name, 'aggregate' in Netapp's terminology;
`api' -- netapp's API type (7 for '7-mode', 8 for 'clustered' mode);
`igroup' -- initiator group name to map LUNs to.
`media' option is currenly unused (meant to speedup paths manipulations).

Minimal multipath.conf:
======================
defaults {
        uid_attribute           ID_WWN_WITH_EXTENSION
}
blacklist {
        wwid .*
}
blacklist_exceptions {
}
multipaths {
}
======================
Usual (and default for jessie) uid_attribute ID_SERIAL is bad because
contains one number (0-8) prepended to real WWN, which potentially can
be different on different SANs.

Currenty it can create/delete thin-provisioned LUNs on my SAN and
create-rollback-delete its snapshots (without memory).

Any reviews and testing are appeciated.

Unfortunately, I'm zero in UI progamming, so will be happy if someone
do corresponding UI changes to fully use this plugin.