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Thread: What network power supply are you using?

  1. #1
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    Default What network power supply are you using for fencing?

    Hi all,
    I was just interested in hearing recommendations, comments, experiences, etc. on what network power supplies you are using (for those folks doing clusters). I know APC or WTI are the recommended vendors, but after searching through the forums and documentation, I noticed that no specific models were mentioned. Anyone have anything to share?

    Cheers,

    Andy
    Last edited by ahurt; 05-22-2006 at 12:30 PM.

  2. #2
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    APC's with PowerChute are amazing.
    I only use APC's. I have a network with 5 T1's, t3, and OC to 3 remote sites from the POP.

    In Tombstone, we have lot's of power outages, and they keep me going.

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    Oops. Are you talking about UPS? I was meaning networked power switches for fencing a malfunctioning server during a failover event.

    Cheers,
    Andy

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    Hi Andy,

    Either the WTI or the APC will work great as a fence device for Red Hat Cluster Suite. In my experience, I liked the WTI a better better: it had some cool features like the ability to log events to remote syslog, easy modem integration, web UI. The physical construction is also really solid.

    However, in my experience the APCs are easier and quicker to order as APC is a bigger company with more VARs.

    Also, although I like the CLI of the WTI over APC, in all likelihood you will use the CLI exactly once (when you first set up the cluster) and then forget it's even there...

    - Ari
    Bugzilla - Wiki - Downloads - Before posting... Search!

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    Just as an FYI, this is not for UPS. These are smart power switches for cluster failover. When a spare machine takes over service for a live machine which has crashed, it uses a "fence device" to make sure its partner is really dead.

    Otherwise, you could have 2 hosts sending SCSI commands to the same shared storage at the same time, a phenomenon known as "split brain syndrome." Needless to say, split brain is a great way to scramble a file system in a hurry.

    If your servers have a "lights out" interface (a lot of high-end chassis' from HP, IBM, etc. have these) you can use that as a fence device. Some SANs also support the ability for one host to log in and lock out another.

    Otherwise, a crude but effective fence device is a smart power switch, as discussed above. Red Hat Cluster Suite ships with send/expect scripts to telnet into the power switch and power down a failed server.

    - Ari
    Bugzilla - Wiki - Downloads - Before posting... Search!

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    Right. I think I used some bad "phraseology" when I said "network power supply." Sorry guys. I am only asking about the network power switch used for fencing as you mention. I just wondered if anyone had anything good/bad to say about specific models of APC or WTI. I should mention that I am working on Apple Xserves, so no "lights-out interfaces" for me. We are doing a highly customized installation on the Mac platform while trying to duplicate some of the redundancy found on the RedHat version. We are doing a couple of Xserves in a failover pair using OS X's built-in IP Failover capabilities (heartbeatd and failoverd +failover scripts). The actual data (store, index, conf, redolog, openldap-data, db, and logger folders) lives on an Xsan volume. This is strictly active/passive failover rather than true clustering mind you. Anyway, one of the issues we have is that the primary server could drop network connectivity, thus triggering a failover event in which the secondary server does an IP takeover and fires up Zimbra. However, if the primary doesn't completely die, it is still connected to the fibre channel fabric and could potentially do bad writes to the Xsan volume ("spurious I/O" as they say in Zimbra-land). Hence, the need for a network power device.

    Cheers,

    Andy

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    Hi,

    I am about to deploy clustered zimbra soon. Would be glad if you guys could point out the specific model for APC networked power supply that supported by redhat/zimbra?

    Would not mind the price, but I need to get the correct hardware ASAP.

    Thanks.

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