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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.

rjt
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1 Answers1

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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.
ewwhite
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  • HPE believed that with two new Gen 9 servers running a new Windows Server Storage Matrix software, that Active/Active might be possible with d2700s. – rjt Mar 30 '16 at 13:25
  • @rjt Just buy a SAN if you need true High Availability. – ewwhite Mar 30 '16 at 13:42
  • Also, I don't think you'll see a performance increase with the types of disks you're working with. – ewwhite Mar 30 '16 at 13:46
  • If closest solution is still just Active / Passive, then i would not expect a performance improvement. – rjt Mar 30 '16 at 14:34
  • I can not take it offline now to check, but could not we just disable one of the RAID cards from doing rebuilds? – rjt Mar 30 '16 at 20:24
  • This is silly. I explained why this won't work. You can either use that information to alter your configuration to something more desirable, or you can give up on the idea of using the current setup in an active/active fashion. – ewwhite Mar 30 '16 at 20:30
  • Nexenta, QuantaStor, Open-E aren't the best solutions you could do. Nexenta is based on aging Solaris and switching to Linux soon, Quanta is basically one-man show and Open-E went downhill many years ago. Being a MSP we used all of them and don't use any of them now. FreeBSD, ZFS, and HAST / RSF-1 (?) will give you higher uptime and better stability. Community is friendly. OpenSUSE can do ZFS as well. There are others. IMHO. – BaronSamedi1958 Mar 31 '16 at 01:30
  • @BaronSamedi1958 I was giving examples. I wouldn't use any of them nowadays. The OP should just find a low-cost HP MSA and reuse his disks/D2700 enclosure. I avoid FreeBSD on HP ProLiant hardware because of poor driver and agent support. – ewwhite Mar 31 '16 at 01:34
  • @ ewwhite You right! Good catch about HPE stuff. We're nearly entirely Dell shop so I dodge the bullet. – BaronSamedi1958 Mar 31 '16 at 01:37
  • @ewwhite, switching to MSA or P2000 requires a total reimaging of our disks, some serious downtime. lowcost MSA is oxymoron. iirc, the MSA can use two SSDs for caching, speeding up everything... that i like. Dont see giving up block level storage for file storage. – rjt Mar 31 '16 at 01:51
  • @rjt I sell HP equipment. P2000 G3 SAN units, which are period-correct for your equipment, range from $2500-$7000, depending on controller. Add disks. Current MSA2040 are more expensive, but there's an option for an MSA1040 as well. They are in the $9k-$20k range, depending on your capacity needs. – ewwhite Mar 31 '16 at 01:57
  • We're one of HPE's biggest storage customers worldwide and they had us test their 'Windows Server Storage Matrix software' (StoreEasy they called it at the time) - it was rubbish - hard to setup, didn't always failover correctly and their own support people barely knew the product - avoid. – Chopper3 Mar 31 '16 at 10:59