Date: Thu, 18 Aug 2016 12:13:51 -0500 From: Linda Kateley <lkateley@kateley.com> To: freebsd-fs@freebsd.org Subject: Re: HAST + ZFS + NFS + CARP Message-ID: <7828fdbc-3a5b-3998-ac54-a896cf02927f@kateley.com> In-Reply-To: <69234c7d-cda9-2d56-b5e0-bb5e3961cc19@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> <B668A4BF-FC28-4210-809A-38D23C214A3B@gmail.com> <69234c7d-cda9-2d56-b5e0-bb5e3961cc19@internetx.com>
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Cool, thanks linda On 8/18/16 3:02 AM, InterNetX - Juergen Gotteswinter wrote: > new day, new things learned :) > > thanks! > > but like said, zrep does its on locking in zfs properties. so even this > is fine > > while true; do zrep sync all; done > > > see > > http://www.bolthole.com/solaris/zrep/ > > the properties look like this > > tank/vmail redundant_metadata all default > tank/vmail zrep:savecount 5 local > tank/vmail zrep:lock-time 20160620101703 local > tank/vmail zrep:master yes local > tank/vmail zrep:src-fs tank/vmail local > tank/vmail zrep:dest-host stor1 local > tank/vmail zrep:src-host stor2 local > tank/vmail zrep:dest-fs tank/vmail local > tank/vmail zrep:lock-pid 10887 local > > > it also takes care of the replication partner, the replicated datasets > are read only until you tell zrep "go go go, become master" > > Simple usage summary: > zrep (init|-i) ZFS/fs remotehost remoteZFSpool/fs > zrep (sync|-S) [-q seconds] ZFS/fs > zrep (sync|-S) [-q seconds] all > zrep (sync|-S) ZFS/fs@snapshot -- temporary retroactive sync > zrep (status|-s) [-v] [(-a|ZFS/fs)] > zrep refresh ZFS/fs -- pull version of sync > zrep (list|-l) [-Lv] > zrep (expire|-e) [-L] (ZFS/fs ...)|(all)|() > zrep (changeconfig|-C) [-f] ZFS/fs remotehost remoteZFSpool/fs > zrep (changeconfig|-C) [-f] [-d] ZFS/fs srchost srcZFSpool/fs > zrep failover [-L] ZFS/fs > zrep takeover [-L] ZFS/fs > > > zrep failover pool/ds -> master sets pool read only, connects to slave, > sets pool on slave rw > > should be easy to combine with carp/devd, but this is the land of vodoo > automagic again which i dont trust that much. > > > Am 18.08.2016 um 09:40 schrieb Ben RUBSON: >> 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" >> > _______________________________________________ > 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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