Date: Thu, 18 Aug 2016 12:17:37 +0100 From: Gary Palmer <gpalmer@freebsd.org> To: Ben RUBSON <ben.rubson@gmail.com> Cc: FreeBSD FS <freebsd-fs@freebsd.org> Subject: Re: HAST + ZFS + NFS + CARP Message-ID: <20160818111737.GB47566@in-addr.com> In-Reply-To: <B668A4BF-FC28-4210-809A-38D23C214A3B@gmail.com> References: <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> <B668A4BF-FC28-4210-809A-38D23C214A3B@gmail.com>
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Isn't this exactly what the lockf command was designed to do for you? I'd also suggest rmdir rather than rm -rf On Thu, Aug 18, 2016 at 09:40:50AM +0200, Ben RUBSON wrote: > 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: > > > > uhm, dont really investigated if it is or not. add a "sync" after that? > > or replace it? > > > > but anyway, thanks for the hint. will dig into this! > > > > Am 18.08.2016 um 09:36 schrieb krad: > >> I didnt think touch was atomic, mkdir is though > >> > >> On 18 August 2016 at 08:32, InterNetX - Juergen Gotteswinter > >> <juergen.gotteswinter@internetx.com > >> <mailto:juergen.gotteswinter@internetx.com>> wrote: > >> > >> > >> > >> 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.. > >>> > >>> 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. > >> > >> no offense, but it sounds a bit like marketing. > >> > >> here: running nexenta ha setup since several years with one catastrophic > >> failure due to split brain > >> > >>> > >>> You do risk losing data if you batch zfs send. It is very hard to run > >>> that real time. > >> > >> depends on how much data changes aka delta size > >> > >> > >> 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. > >> > >> thats the reason why lock files where invented, tools like zrep handle > >> that themself via additional zfs properties > >> > >> or, if one does not trust a single layer > >> > >> -- 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 -- > >> > >> something like this, simple > >> > >> If you lose the sending host before > >>> the receive is complete you won't have a full copy. > >> > >> if rsf fails, and you end up in split brain you loose way more. been > >> there, seen that. > >> > >> 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. > >>> > >>> Anytime you run anything sync it adds latency but makes things safer.. > >> > >> not surprising, it all depends on the usecase > >> > >>> 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. > >>> > >>> Most people I run into (these days) don't mind losing 5 or even 30 > >>> minutes of data. Small shops. > >> > >> you talk about minutes, what delta size are we talking here about? why > >> not using zrep in a loop for example > >> > >> 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. > >> > >> again, usecase. i bet 99% on this list are not operating fortune 500 > >> bank filers > >> > >> 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. > >>> > >>> > >>> 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. :) > >>>> > >>>> 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. > >>>> > >>>> 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? > >>>> > >>>> Chris > >>>> > >>>> Sent from my iPhone 5 > >>>> > >>>> 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: > >>>> > >>>>> 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. > >>>>> > >>>>> linda > >>>>> > >>>>> > >>>>> On 8/17/16 4:52 AM, Julien Cigar wrote: > >>>>>> On Wed, Aug 17, 2016 at 11:05:46AM +0200, InterNetX - Juergen > >>>>>> Gotteswinter wrote: > >>>>>>> > >>>>>>> Am 17.08.2016 um 10:54 schrieb Julien Cigar: > >>>>>>>> On Wed, Aug 17, 2016 at 09:25:30AM +0200, InterNetX - Juergen > >>>>>>>> Gotteswinter wrote: > >>>>>>>>> > >>>>>>>>> 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: > >>>>>>>>>>> > >>>>>>>>>>> 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. > >>>>>>>>>>> > >>>>>>>>>>> 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???t quite like the idea of > >>>>>>>>>> using an essentially unreliable transport > >>>>>>>>>> (Ethernet) for low-level filesystem operations. > >>>>>>>>>> > >>>>>>>>>> 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 .. :) > >>>>>>>> > >>>>>>>> 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: > >>>>>>>> > >>>>>>>> - 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): > >>>>>>>> > >> https://gist.github.com/silenius/f9536e081d473ba4fddd50f59c56b58f > >> <https://gist.github.com/silenius/f9536e081d473ba4fddd50f59c56b58f>; > >>>>>>>> > >>>>>>>> - 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: > >>>>>>>> > >> https://gist.github.com/silenius/344c3e998a1889f988fdfc3ceba57aaf > >> <https://gist.github.com/silenius/344c3e998a1889f988fdfc3ceba57aaf>; and > >>>>>>>> you will have a split-brain scenario > >>>>>>>> > >>>>>>>> - 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 > >>>>>>>> > >>>>>>>> - 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 > >>>>>>>> > >>>>>>>> - A zpool scrub should be run at regular intervals > >>>>>>>> > >>>>>>>> This is my MASTER -> BACKUP CARP script ATM > >>>>>>>> > >> https://gist.github.com/silenius/7f6ee8030eb6b923affb655a259bfef7 > >> <https://gist.github.com/silenius/7f6ee8030eb6b923affb655a259bfef7>; > >>>>>>>> > >>>>>>>> Julien > >>>>>>>> > >>>>>>> 100??? 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. > >>>>>> > >>>>>>> That script works for sure, within very limited cases imho > >>>>>>> > >>>>>>>>> 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 > >>>>>>>>> > >>>>>>>>>> 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???t roll back > >>>>>>>>>> zpool replications :) > >>>>>>>>>> > >>>>>>>>>> ZFS receive does a lot of sanity checks as well. As long as > >> your > >>>>>>>>>> zfs receive doesn???t involve a rollback > >>>>>>>>>> to the latest snapshot, it won???t destroy anything by mistake. > >>>>>>>>>> Just make sure that your replica datasets > >>>>>>>>>> aren???t mounted and zfs receive won???t complain. > >>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> Cheers, > >>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> Borja. > >>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> _______________________________________________ > >>>>>>>>>> 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>>" > >>>>>>>>>> > >>>>>>>>> _______________________________________________ > >>>>>>>>> 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>>" > >>>>> > >>>>> _______________________________________________ > >>>>> 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>>" > >>> > >>> _______________________________________________ > >>> 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>" > >> > >> > > _______________________________________________ > > 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" > > _______________________________________________ > 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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