tag:blogger.com,1999:blog-3993498847203183398.post8086190124467046327..comments2024-03-28T09:19:27.451+00:00Comments on RevK<sup>®</sup>'s ramblings: Night shiftRevKhttp://www.blogger.com/profile/12369263214193333422noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-3993498847203183398.post-84518243053336197572012-03-28T22:50:38.235+01:002012-03-28T22:50:38.235+01:00APC let you run their UPS's as an N+1 farm wit...APC let you run their UPS's as an N+1 farm with the right software. If set properly, if one UPS fails, then the other won't initiate the shutdown unless the relevant redundnacy has been breached.<br />The load is evenly split across the UPS's for servers with dual feeds etc. For routers firewalls etc, you have to take a chance, unless you have dual links etc. Cisco StackPower is quite funky for situations like this - no need for additional PSU's have and reduce your MTBF....<br />I did my loadings based on one UPS having to run the rack - i've done a full load test and it works fine.<br />Also set your UPS's to self load test regularily and at different times in case one dies - which I have seen before.<br />Also, its a good idea as with anything to pull the plug and see what happens every now and then :)Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-84861016452843044172012-03-28T17:36:36.519+01:002012-03-28T17:36:36.519+01:00Be careful with connecting redundant PSUs to both ...Be careful with connecting redundant PSUs to both mains and a UPS, especially if you have diverse power feeds. If your UPS is set to auto-powerdown the servers, power failure on the UPS feed will still initiate shutdown even if the redundant feed is still live. Also remember that the reported runtime of the UPS during normal ops will be 2x or more than the real runtime - I've seen some awkward moments as a result of that!Timthornhttps://www.blogger.com/profile/01821597114397421921noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-44067394609153396702012-03-28T13:33:24.035+01:002012-03-28T13:33:24.035+01:00I stopped using UPSs at home because they kept fai...I stopped using UPSs at home because they kept failing and killing everything. Plus they take up a lot of space ;)1https://www.blogger.com/profile/04266030296611845502noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-67990534324904310622012-03-28T12:51:58.074+01:002012-03-28T12:51:58.074+01:00I've never seen a UPS fail out of the blue, on...I've never seen a UPS fail out of the blue, only when there's a power cut and it fails to take over (dead batteries are a favourite).<br /><br />If you have devices with redundant PSUs (servers, usually) then you connect one direct to the mains and the other via a UPS, assuming you can't afford two UPSs.<br /><br />And change the batteries at regular intervals! (Sad, when they cost so much, but the alternative is a surprisingly quick running out of juice).<br /><br />Cheers,<br />HowardHDRWhttps://www.blogger.com/profile/09148633895717850549noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-37163342318950270352012-03-28T12:49:50.567+01:002012-03-28T12:49:50.567+01:00As Timthorn was saying, look at ATS' from WTI ...As Timthorn was saying, look at ATS' from WTI (http://www.wti.com/p-166-pts-8ne15-1-automatic-power-transfer-switch.aspx) and TrippLite. Basically you feed a PDU both UPS and secondary power (could be another UPS, could be commercial power) and if the active one fails it switches to other. It would have addressed the issue you had.Frank Bulkhttps://www.blogger.com/profile/02004215342995023858noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-86619943935662855882012-03-28T10:49:22.100+01:002012-03-28T10:49:22.100+01:00Unfortunately I've seen quite a few problems c...Unfortunately I've seen quite a few problems caused by UPS failures - my favourite being one where the protected main powering our desktops failed, but the unprotected circuit powering the coffee machine was fine.<br /><br />I've taken to wrapping UPSs in an automatic transfer switch. They take two mains inputs and connect one through to a single output directly via a relay. If that source fails, it switches to the other. As it's just a relay they're quite reliable, though you should ensure that the UPS feed is the primary.Timthornhttps://www.blogger.com/profile/01821597114397421921noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-39269237365033401142012-03-28T09:46:24.954+01:002012-03-28T09:46:24.954+01:00Maybe its just a coincidence, but our UPS reports ...Maybe its just a coincidence, but our UPS reports a 1 second power outage last night @ 2.25, then another @ 3:05. This is about a mile away from your Bracknell offices.Kevin Pearceyhttps://www.blogger.com/profile/10113548997286414290noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-10671911918318555422012-03-28T09:08:17.869+01:002012-03-28T09:08:17.869+01:00Reliability is sometimes quite a difficult concept...Reliability is sometimes quite a difficult concept. I have had to explain on more than one occasion that if you start with a system that has a single point of failure, and you add a new device without thinking it through properly, you will then have two single points of failure, not zero.Psimonkeyhttps://www.blogger.com/profile/02066370602756543973noreply@blogger.com