1. XenServer Storage Integration Deep Dive

2. Agenda XenServer 5.5 Storage Architecture Multipathing
Vendor Integration
StorageLink

3. Citrix XenServer & Essentials 5.5 Family
NEW
Stage Management
Platinum Edition
Lab Management
Provisioning Services (p+v)
Essentials
Provisioning Services (virtual)
Enterprise
Edition
Workload Balancing
NEW
StorageLinkTM
High Availability
Performance Monitoring
Workflow Studio Orchestration
Live Migration (XenMotion)
Active Directory Integration
NEW
Free
Edition
64bit, Windows, Linux Workloads
Generic Storage Snapshotting
XenServer
XenCenter Management
Shared Storage (iSCSI, FC, NFS)
No socket restriction

4. XenServer 5.5 Storage Architecture

5. Expanded Backup Support

6. Storage Technologies XenServer 5.0 / 5.5 NFS / EXT3 XenServer 5.0
iSCSI / FC
XenServer 5.5
iSCSI / FC
Storage Repository
Storage Repository
Storage Repository
Filesystem
LUN
LUN
.VHD
file
.VHD
file
LVM
Logical
Volume
LVM
Logical
Volume
VHD header
VHD header
LVM
Logical
Volume
LVM
Logical
Volume
LVM Volume Group
LVM Volume Group
VM virtual disk

7. LVM XenServer 5.5 (LVHD) Replaces LVM for SRs
Hosts VHD files directly on LVM volumes
Best of both worlds
Features of VHD
Performance of LVM
Adds Advanced Storage features
Fast Cloning
Snapshots
Fast and simple upgrade
Backwards compatible
LVM does not offer features like Fast Cloning and thin provisioning, EXT does but has performance issues because of the ext3 support for AIO+DIO. LVHD addresses this by hosting VHD files directly on LVM volumes.
Backwards compatible: LVHD can handle raw VDIs previously created by LVM SR

8. Multipathing

9. Why using Multipathing?
Path redundancy to storage
Performance increase by load sharing algorithms
Many fibre channel environments by default have multiple paths
LUN 1
FC HBA 1
LUN 1
Storage controller 1
LUN 1
LUN 1
FC HBA 2
Storage controller 2
LUN 1
XenServer
FC Switches
Storage Subsystem

10. Enabling Multipathing
xe host-param-set other- config:multipathing=true uuid=host_uuid
xe host-param-set other- config:multipathhandle=dmp uuid=host_uuid
Note: Do not enable multipathing by other ways (e.g. CLI)!!!

11. XenServer supports 2 multipathing technologies
Device Mapper Multipathing (DMP)
RDAC MPP (mppVhba)
Default
yes no
XenServer version
>= CLI
>= 5.0 Update 2
Management by XenCenter
Support
wide storage range
only LSI controller based storage
Driver / Daemon
multipathd
mppVhba driver
CLI path check
multipath –ll
mpputil
Configuration
/etc/multipath-enabled.conf
/etc/mpp.conf (requires execution of /opt/xensource/bin/update-initrd)
See details:

12. DMP vs RDAC MPP Check if RDAC MPP is running Use only 1 technology
lsmod | grep mppVhba
„multipath –ll“ would show MD device as output (if DMP is active)
Use only 1 technology
When RDAP MPP is running use it
Otherwise use DMP

13. MPP RDAC: Path check mpputil
Lun #0 - WWN: 600a0b80001fdf d9c49b0caa1
LunObject: present
DevState: OPTIMAL
Controller 'A' Path
Path #1: LunPathDevice: present
DevState: OPTIMAL
Path #2: LunPathDevice: present
Controller 'B' Path
mpputil

14. DMP: Path check Monitoring using XenCenter Monitoring using CLI
Command: multipath -ll

15. Multipathing & Software iSCSI

16. iSCSI with Software Initiator
IP addressing to be done by XenServer Dom-0
Multipathing also to be done by XenServer Dom-0
Dom-0 IP configuration is essential
Storage LAN Ctrl 1
XenServer
Dom-0
LUN 1
LUN 1 IP IP
LUN 1 IP
NIC 1
LUN 1
XenServer
Switches
Storage Subsystem

17. Best practice configuration: iSCSI storage with multipathing
Subnet:
Separation of subnets also on IP base
Subnet 1
Storage LAN Adapter 1
Port 1 IP:
NIC 1
NIC 1 IP:
Port 2 IP:
NIC 2
NIC 2 IP:
Storage LAN Adapter 2
Port 1 IP:
LUN 1
Port 2 IP:
XenServer
Subnet 2
FC Switches
Storage Subsystem

18. Not recommended configurations for multipathing and iSCSI:
Both server NICs in same subnet
Mixing of NIC teaming and multipathing
Subnet 1
Subnet 1
NIC 1
NIC 1 IP:
NIC 1
Team IP:
NIC 2
NIC 2 IP:
NIC 2
XenServer
XenServer

19. Multipathing with Software Initiator XenServer 5
XenServer 5 supports Multipathing with iSCSI software initiator
Prerequisites are:
iSCSI target uses same IQN on all ports
iSCSI target ports operate in portal mode
Multipathing reliability has been enhanced massively in XenServer 5.5

20. How to check if iSCSI target operates in portal mode?
Execute iscsiadm -m discovery --type sendtargets --portal <ip address of 1 target>
Output must show alls IPs of the target ports with identical IQN
Example: :3260,1 iqn.strawberry:litchie :3260,2 iqn.strawberry:litchie
When connecting to iSCSI target using XenCenter Storage Repository Wizard, also all target IPs should show up after Discovery

21. NetApp Integration

22. NetApp Storage NetApp Storage supports Multipathing
For configuring NetApp storage and modification of multipath.conf see whitepaper
NetApp typically supports portal mode for iSCSI  multipathing for iSCSI SW Initiator is supported
Especially for low-end NetApp storage (e.g. FAS2020) with limited LAN adapters special considerations take place

23. NetApp low-end storage (iSCSI)
Often limited by NIC configuration
Example: 2 NICs per head
1 aggregate / LUN is represented by 1 head at a time (other head for fault tolerance)
Thus: 2 NICs effectively can be used for storage connection
Typically Filer delivers non-block-based protocols (e.g. CIFS) which also require redundancy as well as block based protocols (e.g. iSCSI)

24. Controller 1 (fault tolerance)
Example FAS2020: Scenario 1 no network reduncancy for iSCSI and CIFS separation of networks
CIFS Network
Controller 0 (active)
NIC 0
NIC 1
NIC 0
Controller 1 (fault tolerance)
NIC 1
NIC 0
NIC 1
iSCSI Network

25. Controller 1 (fault tolerance)
Example FAS2020: Scenario 2 network redundancy for iSCSI and CIFS no separation of networks
CIFS & iSCSI Network
Controller 0
(active)
NIC 0
vif / bond
NIC Bond
NIC 1
NIC 0
Controller 1 (fault tolerance)
NIC 1
NIC 0
vif / bond
NIC 1

26. Controller 1 (fault tolerance)
Example FAS2020: Scenario 3 network redundancy for iSCSI (multipathing) and CIFS separation of networks
NIC Bond
Ctrl 1 (active)
CIFS VLAN
CIFS VLAN
NIC 0
iSCSI VLAN
NIC 1
iSCSI VLAN
NIC 0
Vif /
bond
NIC 1
Multipathing
Controller 1 (fault tolerance)
Same configuration
NIC 2
NIC 3

27. Dell / Equalogic Integration

28. Dell Equalogic Support
XenServer 5.5 includes Adapter (min. firmware required)
Redundant path configuration does not depend on using adapter or not
All PS series are supported as running same OS
StorageLink Gateway support planned

29. Dell / Equalogic
See whitepaper for Dell / Equalogic storage
Each Equalogic has two controllers
Only 1 controller is active
Uses „Group ID“ address on storage side (similar to bonding / teaming on server side)
Only connection over group ID, no direct connection to the iSCSI ports possible
Therefore multipathing cannot be used  bonding on XenServer side

30. Datacore Integration

31. Multipathing architecture with Datacore
Subnet:
Different IQNs for targets – no portal mode possible!!
Subnet 1
Storage Controller 1
Port 1 IP:
NIC 1
NIC 1 IP:
IQN 1
NIC 2
NIC 2 IP:
Storage Controller 2
IQN 2
LUN 1
Port 2 IP:
XenServer
Subnet 2
Switches

32. Datacore hints Special attention for software iSCSI
Follow Datacore technical bulletin: TB15 ftp://support.datacore.com/psp/tech_bulletins/Tech BulletinsAll/TB15b_Citrix%20XenServer_config_50 1.pdf
Datacore in VM
O.k. when not using HA
Configuration possible, but take care about booting the whole environment
Take care when updating XenServer

33. StorageLink

34. Logical advancement of XenServer integrated storage adapters
Netapp & Equalogic
Storage adapter

35. Citrix StorageLink Overview (XenServer)
Data Path
XenServer
Control Path
Guest
SAN Storage Cloud
iSCSI / FC
One point worth mentioning…
StorageLink does not inject any agents or drivers into the control path, control is provided either through support for the native API of the storage or through SMI-S
Also, once StorageLink has created the storage, and wired it to the Control Domain (or Parent Partition for HV), StorageLink gets out of the way and lets the VM talk to that storage LUN as it always would.
For XenServer, the storage is allocated by StorageLink, and appears as a regular XenServer Storage Repository, from which guest virtual machines can create their virtual disks.
Snap-in
for XenServer
StorageLink

36. Leveraging the best of virtualization and storage
StorageLink as basis for
Citrix Essentials
Storage vendor functionalities
Quick provisioning
Snapshots
Quick cloning
Thin-provisioning
Deduplication
Backup and Restore capabilities
We’ve had a definite approach to the marriage of storage and server virtualization ever since the addition of the NetApp SR in XenServer 4.1. With this release, we take this philosophy to the next level. You buy intelligent storage for its powerful thin provisioning, snapshot, replication and deduplication capabilities, as well as the simplification of backup/restore and disaster recovery. We think virtualization infrastructure should let servers and hypervisors do smart computing, arrays and switches do smart storage management, and a single set of interfaces allow you to manage them together.

37. Virtual Storage Manager
StorageLink Overview
XenServer
Hyper-V
Netapp
EqualLogic
DOM0
VSM
Bridge
Parent
Partition
VDS
XenServer
Hyper-V
Data Path
Data Path
Virtual Storage Manager
SAN/NAS
Control Path

38. StorageLink Gateway Overview
SMI-S is the preferred method of integration as it requires no custom development work
XenServer
Dell
At the heart of the new StorageLink is the StorageLink Gateway, a platform that integrates management of the control path for multiple types of storage – from different vendors, via different connection types, and even across different hypervisors.
Storage with providers for the standardized SMI-S interfaces can plug right into StorageLink. Custom adapters can be built by vendors for non-SMI-S devices. With StorageLink, rather than implementing that device-specific interface on every server, it only needs to live in one place, on the StorageLink Gateway – and it can be leveraged by every server running the StorageLink Bridge SR, even in multiple resource pools.
Vendor-specific VSM Storage Adapters run in separate processes

39. Storage Technologies + XenServer 5.5 XenServer 5.5 iSCSI / FC
Storage Repository
Storage Repository
LUN
LUN
LUN
VHD header
VHD header
LVM
Logical
Volume
LVM
Logical
Volume
LVM Volume Group
VM virtual disk

40. Essentials Enterprise
Snapshot types
XenServer (free)
Essentials Enterprise
Snapshot type
Software based snapshot
Hardware based snapshot
(also software based snapshot possible when not using StorageLink)
LUN access model
LVM (1 LUN=x times VDI)
LUN-per-VDI (1 LUN = 1 VDI)
Performance
Good
Superior
Utilization
On XenServer host
On storage subsystem
Overhead
Low
lowest

41. StorageLink: Microsoft look-and-feel

42. Essentials: Example usage scenario Effective creation of VMs from template
VM clone 1x
1. Copy of LUN
2. Modification of Zoning
3. Creation of VM
4. Assignment of LUN to VM
VM clone 3x
1. Copy of LUN
2. Modification of Zoning
3. Creation of VM
4. Assignment of LUN to VM
few mouse clicks VM
Template
Huge manual effort
Effectiveness:
Fast-Cloning using Storage Snapshots
Fully automated storage and SAN configuration
for FC and iSCSI
LUN

43. StorageLink: Supported Storages
StorageLink HCL