An off-the-cuff observation with little real thought put into it: offloading an A feed in one hall and a B feed in the other (if at the same time) seems a reasonable method - intentional or not - of keeping the cumulative data centre load even across feeds.
They should be fine standalone anyway, but high current loads have a way of finding any weakness in the circuit path. As mentioned, use redundant power/ATS whatever to ensure your critical kit up, and have faith in your choice of DC. Karl > On 10/08/2017, at 10:39 AM, Simon Cooper <s...@inbox.com> wrote: > > Thanks guys, appreciate the feedback. > > At NEXTDC we work very hard to keep critical infrastructure maintenance that > impacts racks or the environment within the data hall to an absolute minimum. > > However, some works are required to happen from time to time by law and one > of those activities is a de-energisation and inspection of each of our major > switchboards. This is all about ensuring that the electrical system is safe, > and is an unavoidable piece of work. Rightly so. > > Every rack in a NEXTDC data centre has 2N power feeds offered to it, and we > highly recommend that they are used for every device in the rack. This > occasional maintenance is one of the many reasons we provide this capability. > Any device using the 2N supplies (aka A & B feeds) will simply see its power > swing from one feed to the other. Any rack that is drawing no more that its > contracted power level will have no issue when all devices move from A to B > or vice versa. > > Our notifications were made well in advance, as we want to give customers > time to consider the management of these works and we don't assume that every > rack is perfectly deployed: We are here 24/7 to assist customers with rack > inspections or specific circuit down tests or maybe a controlled move prior > to the day (e.g. for devices that are single fed). > > Also, as we work though those discussions with customers we understand the > timing in relation to their businesses, and we work very hard to coordinate > schedules despite each switch board supporting many different customers and > customer instances across the data centre. Occasionally that means we have > to make a difficult decisions which may result in schedule changes. When > that does happen, we do not compromise our notification periods. > > I'll be happy to discuss these works with anyone - probably best offline or > on the phone - but trust me when I say we are doing our absolute best to keep > your data centre operating safely and reliably for many years to come. > > Thanks, > Simon > COO, NEXTDC > > -----Original Message----- > From: nat...@nightsys.net > Sent: Thu, 10 Aug 2017 05:39:02 +1000 > To: sh...@rackcentral.com > Subject: Re: [AusNOG] NextDC Melbourne - Scheduled Power Maintenance - 15th > August > > This seems reasonable? As long as no single Data Hall has both A and B feeds > removed simultaneously, that seems normal. Doing B on Hall 2 and A on Hall 3 > on the same day does seem slightly adventurous, but not entirely unreasonable > (mostly in terms of if something goes bad in both, staff get stretched thin > remediating issues). > > A and B feeds are designed to provide redundancy to equipment, allowing one > feed to fail and systems to continue on the other. Anything mission critical > should be able to draw from either feed as required (dual PSU), and if there > is a power deficit on one feed (causing circuits to trip), that would imply > the circuits are incorrectly sized? > > In addition, anything mission critical with a single power supply would be on > an ATS you would assume, or a pair of equivalent devices installed with one > on each rail? > > Things break in datacentres, planned maintenance happens sometimes, better > than no maintenance at all :) The fact they are notifying you is better than > not, and it being scheduled is probably still better than unscheduled :) > (easier to ensure sufficient staffing to keep a close eye on things) > > Nathan. > > On Wed, Aug 9, 2017 at 3:43 PM, Shaun McGuane <sh...@rackcentral.com > <mailto:sh...@rackcentral.com>> wrote: > Here is the entire scheduled maintenance windows for all the halls we occupy. > > > > DataHall 2 > > A Feed - Tuesday 8th August 2017 07:00 UTC +10 until 16:00 UTC +10. > B Feed - Tuesday 15th August 2017 07:00 UTC +10 until 16:00 UTC +10. > > > > DataHall 3 > > A Feed - Tuesday 15th August 2017 07:00 UTC +10 until 16:00 UTC +10 > B Feed - Monday 14th August 2017 07:00 UTC +10 until 16:00 UTC +10 > > > > DataHall 4 > > B Feed - Tuesday 15th August 2017 07:00 UTC +10 until 16:00 UTC +10. > > > > · So looks like no power on 3 data halls B feeds on the same day. > > · Data Hall 2 was scheduled for A rail on the 8th of August but has > been re-scheduled with no new date of works. > > · Data Hall 3 was scheduled for A rail on the > > > > Problem is that I have 3x separate dates on 3 separate e-mails for Data Hall > 3 and I have requested a revised clarification > > Just now on the above as there has already been re-schedules for Data Hall 2 > and 3. > > > > This feels like it’s going sideways and it has not even started. > > > > Regards > > Shaun > > > > > > From: AusNOG [mailto:ausnog-boun...@lists.ausnog.net > <mailto:ausnog-boun...@lists.ausnog.net>] On Behalf Of Murat Sener > Sent: Wednesday, 9 August 2017 3:20 PM > To: Matthew VK3EVL <hit...@itglowz.com <mailto:hit...@itglowz.com>>; > ausnog@lists.ausnog.net <mailto:ausnog@lists.ausnog.net> > > Subject: Re: [AusNOG] NextDC Melbourne - Scheduled Power Maintenance - 15th > August > > > > We have been told only Feed B in Data hall 2 will be effected as per original > schedule and Feed A is yet to be rescheduled. <> > > > > > > > <image001.png> > > Murat Sener Datacentre Manager > > PREMIER Technology Solutions > P. 1300 76 76 48 F. 1300 76 76 49 M. 0450 604 350 > > > > How am I doing? Let us know! > SIMPLY CLICK ON A FACE TO GIVE FEEDBACK > > GREAT > > AVERAGE > > BAD > > <image002.png> > <https://www.crewhu.com/survey.html?crewHuID=qm0Hxbzstp&employeeID=rLeIz2SkIa&type=signat&rating=5> > > <image003.png> > <https://www.crewhu.com/survey.html?crewHuID=qm0Hxbzstp&employeeID=rLeIz2SkIa&type=signat&rating=0> > > <image004.png> > <https://www.crewhu.com/survey.html?crewHuID=qm0Hxbzstp&employeeID=rLeIz2SkIa&type=signat&rating=-5> > > > From: AusNOG [mailto:ausnog-boun...@lists.ausnog.net > <mailto:ausnog-boun...@lists.ausnog.net>] On Behalf Of Matthew VK3EVL > Sent: Wednesday, 9 August 2017 3:13 PM > To: ausnog@lists.ausnog.net <mailto:ausnog@lists.ausnog.net> > Subject: Re: [AusNOG] NextDC Melbourne - Scheduled Power Maintenance - 15th > August > > > > What about both feeds happening on the same day at the same time? > > > > On 9/08/2017 2:55 PM, Shaun McGuane wrote: > > HI Damien, > > > > My apologies that’s correct – but isn’t anyone concerned about the works > being completed during business hours? > > What about increased loading of the active rail once one of them is switched > off for these works? > > > > Regards > > Shaun > > > > > > From: Damien Gardner Jnr [mailto:rend...@rendrag.net > <mailto:rend...@rendrag.net>] > Sent: Wednesday, 9 August 2017 2:39 PM > To: <ausnog@lists.ausnog.net> <mailto:ausnog@lists.ausnog.net> > <ausnog@lists.ausnog.net> <mailto:ausnog@lists.ausnog.net>; Shaun McGuane > <sh...@rackcentral.com> <mailto:sh...@rackcentral.com> > Subject: Re: [AusNOG] NextDC Melbourne - Scheduled Power Maintenance - 15th > August > > > > It says 7am -> 4pm in what you quoted? (UTC+10 is AEST) > > > > On Wed, 9 Aug 2017 at 2:36 pm, Shaun McGuane <sh...@rackcentral.com > <mailto:sh...@rackcentral.com>> wrote: > > HI Noggers, > > > > Has anyone seen this scheduled maintenance notification happening next week? > > They maybe upgrading feeds or boards throughout the datacentre – has everyone > seen this notification of works? > > It appears to be happening starting 5PM through to 2AM AEST for all Datahalls > on the same date. > > > > > > WHAT: > NEXTDC M1 Melbourne data centre, with the assistance of specialist > contractors, will conduct offline preventative electrical maintenance work on > high-voltage and low-voltage main isolators. This will affect A and B feeds > to the racks in Data Hall 2/3/4 on the 15th of August. > > WHEN: > A Feed - Tuesday 15th August 2017 07:00 UTC +10 until 16:00 UTC +10. > B Feed - Tuesday 15th August 2017 07:00 UTC +10 until 16:00 UTC +10. > > HOW AM I AFFECTED? > Due to the nature of the work a single feed will be removed as per the dates > and times above. We recommend that customers balance the power between both > power rails to minimise impact during this period. If you have single feed > devices we recommend you: > > > > Regards > > Shaun > > > > > > > > _______________________________________________ > AusNOG mailing list > AusNOG@lists.ausnog.net <mailto:AusNOG@lists.ausnog.net> > http://lists.ausnog.net/mailman/listinfo/ausnog > <http://lists.ausnog.net/mailman/listinfo/ausnog> > -- > > Damien Gardner Jnr > VK2TDG. Dip EE. GradIEAust > rend...@rendrag.net <mailto:rend...@rendrag.net> - http://www.rendrag.net/ > <http://www.rendrag.net/> > -- > We rode on the winds of the rising storm, > We ran to the sounds of thunder. > We danced among the lightning bolts, > and tore the world asunder > > > > > _______________________________________________ > AusNOG mailing list > AusNOG@lists.ausnog.net <mailto:AusNOG@lists.ausnog.net> > http://lists.ausnog.net/mailman/listinfo/ausnog > <http://lists.ausnog.net/mailman/listinfo/ausnog> > > > > MESSAGE PROTECTED BY PREMIER TECHNOLOGY SOLUTIONS > <http://www.premiertech.com.au/> - POWERED BY MAILGUARD > <http://www.mailguard.com.au/mg>. > Report this message as spam > <https://console.mailguard.com.au/ras/1RqQHQIE5J/6DWUZjiMDnlts7JYyCLNB3/0> > > > > MESSAGE PROTECTED BY PREMIER TECHNOLOGY SOLUTIONS > <http://www.premiertech.com.au/> - POWERED BY MAILGUARD > <http://www.mailguard.com.au/mg>. > > > > _______________________________________________ > AusNOG mailing list > AusNOG@lists.ausnog.net <mailto:AusNOG@lists.ausnog.net> > http://lists.ausnog.net/mailman/listinfo/ausnog > <http://lists.ausnog.net/mailman/listinfo/ausnog> > > > _______________________________________________ > AusNOG mailing list > AusNOG@lists.ausnog.net > http://lists.ausnog.net/mailman/listinfo/ausnog
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