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rjt
Asked: 2016-03-30 20:47:52 +0800 CST

Active/Active MultiPathIO to two HP d2700s?

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Our XenServer 6.5 hosts connect over ethernet to shared SAS storage via a single Linux based HP DL360 G6 "bridge". This single StorageServer bridges ethernet to SAS and shares out via an iSCSI daemon.

3x HP DL380 G6 <---> Ethernet<-->HP DL 360 G6 with HP p411 SAS RAID card<---mini SAS cables --->Two HP d2700 SAS enclosures <--> dual port SAS drives.

Can we add a second DL 360 with p411 (other cards not ruled out) to get Active/Active pathways from the XEN hosts to the iSCSI/SAS dual port drives?
Not only to increase redundancy but also increase performance.

Is Citrix XenServer really smart enough to limit which hosts talks to the LVM such that the same LVM is not accessed by two different channels?

Even if XEN is that smart, how would the RAID cards in two different servers coordinate rebuilds of the arrays when drives go bad?

XenServer 6.5 is based on RHEL / CentOS 5. Device Mapper compatibility is listed in /usr/share/doc/device-mapper-multipath-0.X.Y/multipath.conf.defaults. This file in CentOS6.7 mentions the big brothers to the d2700 such as the P2000 G3 and the MSA2012i among others. multipath.conf.defaults does NOT list the d2700 nor d2600.

xen

1 Answers

  1. Best Answer

    No. This won't be possible.

    • The HP D2700 is a JBOD enclosure. It is intended for connection to a single server or to a SAN (cascaded JBOD attached to an MSA2000, MSA2040 or P2000 SAN)
    • The HP Smart Array RAID controllers don't support multi-controller high availability.
    • If you want a real HA solution, you could move to an HP P2000 G3 or MSA2040 SAN. The disks you have in your D2700 are compatible. The D2700 can be used as expansion for the SAN.
    • If you replace the P411 controllers with SAS HBAs (e.g. LSI 9211-8i), you could build a solution using two servers and multipath SAS to the D2700s using ZFS or any storage appliance OS (Nexenta, QuantaStor, Open-E) that's capable of this configuration. These would still be Active/Passive since there's a need to control (fence) which disks are available to which head node.
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