Date: Fri, 03 May 2019 03:00:05 +1000 From: Michelle Sullivan <michelle@sorbs.net> To: "N.J. Mann" <njm@njm.me.uk> Cc: freebsd-stable <freebsd-stable@freebsd.org> Subject: Re: ZFS... Message-ID: <0D0C3E6C-3ED3-4629-BD26-B4D23ABC3800@sorbs.net> In-Reply-To: <51f1813c-5666-33a4-2155-59ba706a1948@sorbs.net> References: <30506b3d-64fb-b327-94ae-d9da522f3a48@sorbs.net> <CAOhm=5oRTkr6L037fzh4DKpqgMY5XJVp60t934en3%2BrGCnbFJw@mail.gmail.com> <6D7D690B-31DA-4A86-BB34-64A977B91D4F@sorbs.net> <22E6AED197D46F831645E296@triton.njm.me.uk> <51f1813c-5666-33a4-2155-59ba706a1948@sorbs.net>
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Michelle Sullivan http://www.mhix.org/ Sent from my iPad > On 03 May 2019, at 02:24, Michelle Sullivan <michelle@sorbs.net> wrote: >=20 > N.J. Mann wrote: >> Hi, >>=20 >>=20 >> On Thursday, May 02, 2019 09:27:36 +1000 Michelle Sullivan <michelle@sorb= s.net> wrote: >>>> On 02 May 2019, at 02:16, Chris <chrcoluk@gmail.com> wrote: >>>>=20 >>>> Your story is so unusual I am wondering if its not fiction, I mean all >>>> sorts of power cuts where it just so happens the UPS fails every time, >>> The only =E2=80=9Cfiction=E2=80=9D is the date.. was the 10th not the 19= th March... https://www.southcoastregister.com.au/story/5945663/homes-left-w= ithout-power-after-electrical-pole-destroyed-in-sanctuary-point-accident/ >>>=20 >>> UPSes do glitch out sometimes, but rarely.. they do have problems when 1= 1kv comes down a 240v line though... >> I am sorry to hear about your loss of data, but where does the 11kV come f= rom? >> I can understand 415V, i.e. two phases in contact, but the type of overhe= ad >> lines in the pictures you reference are three phase each typically 240V t= o >> neutral and 415V between two phases. >>=20 > Bottom lines on the power pole are normal 240/415 .. top lines are the 11K= V distribution network. >=20 Oh and just so you know, it=E2=80=99s sorta impossible to get 415 down a 24= 0v connection, for that to happen you=E2=80=99d need to disconnect any retur= n (neutral) and then connect it to another phase... and as most connections= are TNE that means dropping the cables on the incoming connection and havin= g a really dodgy connection. =20 It is very unusual to get 11kv down a distribution phase and pretty much the= only time I have ever seen it is when a cable is cut (a 11kv line) and it f= alls onto a supply cable... lightning strikes are the most common case. The= second most common (and they are really not) is someone taking out a pole. The system is designed to drop power out instantly when it happens which is w= hy it is rare to do damage but we (sparkles) all know that it=E2=80=99s mill= iseconds not =E2=80=9Cinstantly=E2=80=9D. Unfortunate part of this is if th= ey hit the power pole next up the road.. there was no 11kv distribution cabl= es.. as you can=E2=80=99t see in the photos the pole on the other side of t= he road had a transformer (not the same one that blew the night before...) It was a classic example of Murphy=E2=80=99s law, (if something can go wrong= to make @ bad situation worse, it will).. if it wasn=E2=80=99t in the midd= le of a resilver it would not have had this issue. If a transformer hadn=E2= =80=99t blown on the network 6 hours before I wouldn=E2=80=99t have even bee= n connected to that substation. If the transformer that blew hadn=E2=80=99t= ZFS would have just don=E2=80=99t the rollback I did the night before... i= f I hadn=E2=80=99t gone to the server room and checked everything and restar= ted the resilver it wouldn=E2=80=99t have been doing anything to the drives.= If the UPSes hadn=E2=80=99t failed on the night it would have probably bee= n waiting for me to rollback the 5 seconds when the pole was taken out...etc= ...etc... So many... =E2=80=9Cif this didn=E2=80=99t happens it would have been ok...=E2= =80=9D >=20 >> Best wishes, >> Nick. >=20 >=20 > --=20 > Michelle Sullivan > http://www.mhix.org/ >=20 > _______________________________________________ > freebsd-stable@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org"
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