Date: Thu, 18 Aug 2016 09:40:50 +0200 From: Ben RUBSON <ben.rubson@gmail.com> To: FreeBSD FS <freebsd-fs@freebsd.org> Subject: Re: HAST + ZFS + NFS + CARP Message-ID: <B668A4BF-FC28-4210-809A-38D23C214A3B@gmail.com> In-Reply-To: <409301a7-ce03-aaa3-c4dc-fa9f9ba66e01@internetx.com> References: <61283600-A41A-4A8A-92F9-7FAFF54DD175@ixsystems.com> <20160704183643.GI41276@mordor.lan> <AE372BF0-02BE-4BF3-9073-A05DB4E7FE34@ixsystems.com> <20160704193131.GJ41276@mordor.lan> <E7D42341-D324-41C7-B03A-2420DA7A7952@sarenet.es> <20160811091016.GI70364@mordor.lan> <1AA52221-9B04-4CF6-97A3-D2C2B330B7F9@sarenet.es> <472bc879-977f-8c4c-c91a-84cc61efcd86@internetx.com> <20160817085413.GE22506@mordor.lan> <465bdec5-45b7-8a1d-d580-329ab6d4881b@internetx.com> <20160817095222.GG22506@mordor.lan> <52d5b687-1351-9ec5-7b67-bfa0be1c8415@kateley.com> <92F4BE3D-E4C1-4E5C-B631-D8F124988A83@gmail.com> <6b866b6e-1ab3-bcc5-151b-653e401742bd@kateley.com> <7468cc18-85e8-3765-2b2b-a93ef73ca05a@internetx.com> <CALfReydFhMfFpQ1v6F8nv5a-UN-EnY5ipYe_oe_edYJfBzjXVQ@mail.gmail.com> <409301a7-ce03-aaa3-c4dc-fa9f9ba66e01@internetx.com>
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Yep this is better : if mkdir <lockdir> then do_your_job rm -rf <lockdir> fi > On 18 Aug 2016, at 09:38, InterNetX - Juergen Gotteswinter = <juergen.gotteswinter@internetx.com> wrote: >=20 > uhm, dont really investigated if it is or not. add a "sync" after = that? > or replace it? >=20 > but anyway, thanks for the hint. will dig into this! >=20 > Am 18.08.2016 um 09:36 schrieb krad: >> I didnt think touch was atomic, mkdir is though >>=20 >> On 18 August 2016 at 08:32, InterNetX - Juergen Gotteswinter >> <juergen.gotteswinter@internetx.com >> <mailto:juergen.gotteswinter@internetx.com>> wrote: >>=20 >>=20 >>=20 >> Am 17.08.2016 um 20:03 schrieb Linda Kateley: >>> I just do consulting so I don't always get to see the end of the >>> project. Although we are starting to do more ongoing support so we = can >>> see the progress.. >>>=20 >>> I have worked with some of the guys from high-availability.com = <http://high-availability.com>; for maybe >>> 20 years. RSF-1 is the cluster that is bundled with nexenta. Does = work >>> beautifully with omni/illumos. The one customer I have running it in >>> prod is an isp in south america running openstack and zfs on freebsd = as >>> iscsi. Big boxes, 90+ drives per frame. If someone would like try = it, i >>> have some contacts there. Ping me offlist. >>=20 >> no offense, but it sounds a bit like marketing. >>=20 >> here: running nexenta ha setup since several years with one = catastrophic >> failure due to split brain >>=20 >>>=20 >>> You do risk losing data if you batch zfs send. It is very hard to = run >>> that real time. >>=20 >> depends on how much data changes aka delta size >>=20 >>=20 >> You have to take the snap then send the snap. Most >>> people run in cron, even if it's not in cron, you would want one to >>> finish before you started the next. >>=20 >> thats the reason why lock files where invented, tools like zrep = handle >> that themself via additional zfs properties >>=20 >> or, if one does not trust a single layer >>=20 >> -- snip -- >> #!/bin/sh >> if [ ! -f /var/run/replic ] ; then >> touch /var/run/replic >> /blah/path/zrep sync all >> /var/log/zfsrepli.log >> rm -f /var/run/replic >> fi >> -- snip -- >>=20 >> something like this, simple >>=20 >> If you lose the sending host before >>> the receive is complete you won't have a full copy. >>=20 >> if rsf fails, and you end up in split brain you loose way more. = been >> there, seen that. >>=20 >> With zfs though you >>> will probably still have the data on the sending host, however long = it >>> takes to bring it back up. RSF-1 runs in the zfs stack and send the >>> writes to the second system. It's kind of pricey, but actually much = less >>> expensive than commercial alternatives. >>>=20 >>> Anytime you run anything sync it adds latency but makes things = safer.. >>=20 >> not surprising, it all depends on the usecase >>=20 >>> There is also a cool tool I like, called zerto for vmware that sits = in >>> the hypervisor and sends a sync copy of a write locally and then an >>> async remotely. It's pretty cool. Although I haven't run it myself, = have >>> a bunch of customers running it. I believe it works with proxmox = too. >>>=20 >>> Most people I run into (these days) don't mind losing 5 or even 30 >>> minutes of data. Small shops. >>=20 >> you talk about minutes, what delta size are we talking here about? = why >> not using zrep in a loop for example >>=20 >> They usually have a copy somewhere else. >>> Or the cost of 5-30 minutes isn't that great. I used work as a >>> datacenter architect for sun/oracle with only fortune 500. There = losing >>> 1 sec could put large companies out of business. I worked with banks = and >>> exchanges. >>=20 >> again, usecase. i bet 99% on this list are not operating fortune = 500 >> bank filers >>=20 >> They couldn't ever lose a single transaction. Most people >>> nowadays do the replication/availability in the application though = and >>> don't care about underlying hardware, especially disk. >>>=20 >>>=20 >>> On 8/17/16 11:55 AM, Chris Watson wrote: >>>> Of course, if you are willing to accept some amount of data loss = that >>>> opens up a lot more options. :) >>>>=20 >>>> Some may find that acceptable though. Like turning off fsync with >>>> PostgreSQL to get much higher throughput. As little no as you are >> made >>>> *very* aware of the risks. >>>>=20 >>>> It's good to have input in this thread from one with more = experience >>>> with RSF-1 than the rest of us. You confirm what others have that >> said >>>> about RSF-1, that it's stable and works well. What were you = deploying >>>> it on? >>>>=20 >>>> Chris >>>>=20 >>>> Sent from my iPhone 5 >>>>=20 >>>> On Aug 17, 2016, at 11:18 AM, Linda Kateley <lkateley@kateley.com >> <mailto:lkateley@kateley.com> >>>> <mailto:lkateley@kateley.com <mailto:lkateley@kateley.com>>> wrote: >>>>=20 >>>>> The question I always ask, as an architect, is "can you lose 1 >> minute >>>>> worth of data?" If you can, then batched replication is perfect. = If >>>>> you can't.. then HA. Every place I have positioned it, rsf-1 has >>>>> worked extremely well. If i remember right, it works at the dmu. I >>>>> would suggest try it. They have been trying to have a full freebsd >>>>> solution, I have several customers running it well. >>>>>=20 >>>>> linda >>>>>=20 >>>>>=20 >>>>> On 8/17/16 4:52 AM, Julien Cigar wrote: >>>>>> On Wed, Aug 17, 2016 at 11:05:46AM +0200, InterNetX - Juergen >>>>>> Gotteswinter wrote: >>>>>>>=20 >>>>>>> Am 17.08.2016 um 10:54 schrieb Julien Cigar: >>>>>>>> On Wed, Aug 17, 2016 at 09:25:30AM +0200, InterNetX - Juergen >>>>>>>> Gotteswinter wrote: >>>>>>>>>=20 >>>>>>>>> Am 11.08.2016 um 11:24 schrieb Borja Marcos: >>>>>>>>>>> On 11 Aug 2016, at 11:10, Julien Cigar = <julien@perdition.city >>>>>>>>>>> <mailto:julien@perdition.city >> <mailto:julien@perdition.city>>> wrote: >>>>>>>>>>>=20 >>>>>>>>>>> As I said in a previous post I tested the zfs send/receive >>>>>>>>>>> approach (with >>>>>>>>>>> zrep) and it works (more or less) perfectly.. so I concur in >>>>>>>>>>> all what you >>>>>>>>>>> said, especially about off-site replicate and synchronous >>>>>>>>>>> replication. >>>>>>>>>>>=20 >>>>>>>>>>> Out of curiosity I'm also testing a ZFS + iSCSI + CARP at = the >>>>>>>>>>> moment, >>>>>>>>>>> I'm in the early tests, haven't done any heavy writes yet, = but >>>>>>>>>>> ATM it >>>>>>>>>>> works as expected, I havent' managed to corrupt the zpool. >>>>>>>>>> I must be too old school, but I don=E2=80=99t quite like the = idea of >>>>>>>>>> using an essentially unreliable transport >>>>>>>>>> (Ethernet) for low-level filesystem operations. >>>>>>>>>>=20 >>>>>>>>>> In case something went wrong, that approach could risk >>>>>>>>>> corrupting a pool. Although, frankly, >>>>>>>>>> ZFS is extremely resilient. One of mine even survived a SAS = HBA >>>>>>>>>> problem that caused some >>>>>>>>>> silent corruption. >>>>>>>>> try dual split import :D i mean, zpool -f import on 2 machines >>>>>>>>> hooked up >>>>>>>>> to the same disk chassis. >>>>>>>> Yes this is the first thing on the list to avoid .. :) >>>>>>>>=20 >>>>>>>> I'm still busy to test the whole setup here, including the >>>>>>>> MASTER -> BACKUP failover script (CARP), but I think you can >> prevent >>>>>>>> that thanks to: >>>>>>>>=20 >>>>>>>> - As long as ctld is running on the BACKUP the disks are locked >>>>>>>> and you can't import the pool (even with -f) for ex (filer2 >> is the >>>>>>>> BACKUP): >>>>>>>>=20 >> https://gist.github.com/silenius/f9536e081d473ba4fddd50f59c56b58f >> = <https://gist.github.com/silenius/f9536e081d473ba4fddd50f59c56b58f>; >>>>>>>>=20 >>>>>>>> - The shared pool should not be mounted at boot, and you should >>>>>>>> ensure >>>>>>>> that the failover script is not executed during boot time too: >>>>>>>> this is >>>>>>>> to handle the case wherein both machines turn off and/or >> re-ignite at >>>>>>>> the same time. Indeed, the CARP interface can "flip" it's = status >>>>>>>> if both >>>>>>>> machines are powered on at the same time, for ex: >>>>>>>>=20 >> https://gist.github.com/silenius/344c3e998a1889f988fdfc3ceba57aaf >> = <https://gist.github.com/silenius/344c3e998a1889f988fdfc3ceba57aaf>; and >>>>>>>> you will have a split-brain scenario >>>>>>>>=20 >>>>>>>> - Sometimes you'll need to reboot the MASTER for some $reasons >>>>>>>> (freebsd-update, etc) and the MASTER -> BACKUP switch should = not >>>>>>>> happen, this can be handled with a trigger file or something = like >>>>>>>> that >>>>>>>>=20 >>>>>>>> - I've still have to check if the order is OK, but I think >> that as >>>>>>>> long >>>>>>>> as you shutdown the replication interface and that you adapt = the >>>>>>>> advskew (including the config file) of the CARP interface >> before the >>>>>>>> zpool import -f in the failover script you can be relatively >>>>>>>> confident >>>>>>>> that nothing will be written on the iSCSI targets >>>>>>>>=20 >>>>>>>> - A zpool scrub should be run at regular intervals >>>>>>>>=20 >>>>>>>> This is my MASTER -> BACKUP CARP script ATM >>>>>>>>=20 >> https://gist.github.com/silenius/7f6ee8030eb6b923affb655a259bfef7 >> = <https://gist.github.com/silenius/7f6ee8030eb6b923affb655a259bfef7>; >>>>>>>>=20 >>>>>>>> Julien >>>>>>>>=20 >>>>>>> 100=E2=82=AC question without detailed looking at that script. = yes from a >>>>>>> first >>>>>>> view its super simple, but: why are solutions like rsf-1 such = more >>>>>>> powerful / featurerich. Theres a reason for, which is that >> they try to >>>>>>> cover every possible situation (which makes more than sense >> for this). >>>>>> I've never used "rsf-1" so I can't say much more about it, but >> I have >>>>>> no doubts about it's ability to handle "complex situations", = where >>>>>> multiple nodes / networks are involved. >>>>>>=20 >>>>>>> That script works for sure, within very limited cases imho >>>>>>>=20 >>>>>>>>> kaboom, really ugly kaboom. thats what is very likely to = happen >>>>>>>>> sooner >>>>>>>>> or later especially when it comes to homegrown automatism >> solutions. >>>>>>>>> even the commercial parts where much more time/work goes >> into such >>>>>>>>> solutions fail in a regular manner >>>>>>>>>=20 >>>>>>>>>> The advantage of ZFS send/receive of datasets is, however, = that >>>>>>>>>> you can consider it >>>>>>>>>> essentially atomic. A transport corruption should not cause >>>>>>>>>> trouble (apart from a failed >>>>>>>>>> "zfs receive") and with snapshot retention you can even roll >>>>>>>>>> back. You can=E2=80=99t roll back >>>>>>>>>> zpool replications :) >>>>>>>>>>=20 >>>>>>>>>> ZFS receive does a lot of sanity checks as well. As long as >> your >>>>>>>>>> zfs receive doesn=E2=80=99t involve a rollback >>>>>>>>>> to the latest snapshot, it won=E2=80=99t destroy anything by = mistake. >>>>>>>>>> Just make sure that your replica datasets >>>>>>>>>> aren=E2=80=99t mounted and zfs receive won=E2=80=99t = complain. >>>>>>>>>>=20 >>>>>>>>>>=20 >>>>>>>>>> Cheers, >>>>>>>>>>=20 >>>>>>>>>>=20 >>>>>>>>>>=20 >>>>>>>>>>=20 >>>>>>>>>> Borja. >>>>>>>>>>=20 >>>>>>>>>>=20 >>>>>>>>>>=20 >>>>>>>>>> _______________________________________________ >>>>>>>>>> freebsd-fs@freebsd.org <mailto:freebsd-fs@freebsd.org> >> <mailto:freebsd-fs@freebsd.org <mailto:freebsd-fs@freebsd.org>> >> mailing list >>>>>>>>>> https://lists.freebsd.org/mailman/listinfo/freebsd-fs >> <https://lists.freebsd.org/mailman/listinfo/freebsd-fs>; >>>>>>>>>> To unsubscribe, send any mail to >>>>>>>>>> "freebsd-fs-unsubscribe@freebsd.org >> <mailto:freebsd-fs-unsubscribe@freebsd.org> >>>>>>>>>> <mailto:freebsd-fs-unsubscribe@freebsd.org >> <mailto:freebsd-fs-unsubscribe@freebsd.org>>" >>>>>>>>>>=20 >>>>>>>>> _______________________________________________ >>>>>>>>> freebsd-fs@freebsd.org <mailto:freebsd-fs@freebsd.org> >> <mailto:freebsd-fs@freebsd.org <mailto:freebsd-fs@freebsd.org>> >> mailing list >>>>>>>>> https://lists.freebsd.org/mailman/listinfo/freebsd-fs >> <https://lists.freebsd.org/mailman/listinfo/freebsd-fs>; >>>>>>>>> To unsubscribe, send any mail to >>>>>>>>> "freebsd-fs-unsubscribe@freebsd.org >> <mailto:freebsd-fs-unsubscribe@freebsd.org> >>>>>>>>> <mailto:freebsd-fs-unsubscribe@freebsd.org >> <mailto:freebsd-fs-unsubscribe@freebsd.org>>" >>>>>=20 >>>>> _______________________________________________ >>>>> freebsd-fs@freebsd.org <mailto:freebsd-fs@freebsd.org> >> <mailto:freebsd-fs@freebsd.org <mailto:freebsd-fs@freebsd.org>> >> mailing list >>>>> https://lists.freebsd.org/mailman/listinfo/freebsd-fs >> <https://lists.freebsd.org/mailman/listinfo/freebsd-fs>; >>>>> To unsubscribe, send any mail to >> "freebsd-fs-unsubscribe@freebsd.org >> <mailto:freebsd-fs-unsubscribe@freebsd.org> >>>>> <mailto:freebsd-fs-unsubscribe@freebsd.org >> <mailto:freebsd-fs-unsubscribe@freebsd.org>>" >>>=20 >>> _______________________________________________ >>> freebsd-fs@freebsd.org <mailto:freebsd-fs@freebsd.org> mailing list >>> https://lists.freebsd.org/mailman/listinfo/freebsd-fs >> <https://lists.freebsd.org/mailman/listinfo/freebsd-fs>; >>> To unsubscribe, send any mail to >> "freebsd-fs-unsubscribe@freebsd.org >> <mailto:freebsd-fs-unsubscribe@freebsd.org>" >> _______________________________________________ >> freebsd-fs@freebsd.org <mailto:freebsd-fs@freebsd.org> mailing = list >> https://lists.freebsd.org/mailman/listinfo/freebsd-fs >> <https://lists.freebsd.org/mailman/listinfo/freebsd-fs>; >> To unsubscribe, send any mail to = "freebsd-fs-unsubscribe@freebsd.org >> <mailto:freebsd-fs-unsubscribe@freebsd.org>" >>=20 >>=20 > _______________________________________________ > freebsd-fs@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org"
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