From owner-freebsd-fs@freebsd.org Thu Aug 18 07:32:32 2016 Return-Path: Delivered-To: freebsd-fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 42D7ABBE15A for ; Thu, 18 Aug 2016 07:32:32 +0000 (UTC) (envelope-from juergen.gotteswinter@internetx.com) Received: from mx1.internetx.com (mx1.internetx.com [62.116.129.39]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id C02C51A25 for ; Thu, 18 Aug 2016 07:32:31 +0000 (UTC) (envelope-from juergen.gotteswinter@internetx.com) Received: from localhost (localhost [127.0.0.1]) by mx1.internetx.com (Postfix) with ESMTP id 359D145FC0FB; Thu, 18 Aug 2016 09:32:23 +0200 (CEST) X-Virus-Scanned: InterNetX GmbH amavisd-new at ix-mailer.internetx.de Received: from mx1.internetx.com ([62.116.129.39]) by localhost (ix-mailer.internetx.de [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id fV-FbX44V-04; Thu, 18 Aug 2016 09:32:16 +0200 (CEST) Received: from [192.168.100.26] (pizza.internetx.de [62.116.129.3]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by mx1.internetx.com (Postfix) with ESMTPSA id E59964C4C688; Thu, 18 Aug 2016 09:32:16 +0200 (CEST) Reply-To: juergen.gotteswinter@internetx.com Subject: Re: HAST + ZFS + NFS + CARP References: <61283600-A41A-4A8A-92F9-7FAFF54DD175@ixsystems.com> <20160704183643.GI41276@mordor.lan> <20160704193131.GJ41276@mordor.lan> <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> To: linda@kateley.com, Chris Watson Cc: freebsd-fs@freebsd.org From: InterNetX - Juergen Gotteswinter Organization: InterNetX GmbH Message-ID: <7468cc18-85e8-3765-2b2b-a93ef73ca05a@internetx.com> Date: Thu, 18 Aug 2016 09:32:14 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <6b866b6e-1ab3-bcc5-151b-653e401742bd@kateley.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 Aug 2016 07:32:32 -0000 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 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 > > 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 >>>>>>>> > 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 >>>>>> >>>>>> - 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 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 >>>>>> >>>>>> 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 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 >>> " > > _______________________________________________ > 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"