I don't believe I have this kind of behavior. AFAIK, files are created or modified by only 1 client at a time.
On Mon, May 21, 2018, 19:06 Brady Deetz <bde...@gmail.com> wrote: > What is your expected behavior for when Client A writes to File B in > Datacenter 1 and Client C writes to File B in Datacenter 2 at the exact > same time? > > I don't think you can perfectly achieve what you are requesting with Ceph > or many other storage solutions. > > On Mon, May 21, 2018 at 9:33 AM, Up Safe <upands...@gmail.com> wrote: > >> I'll explain. >> Right now we have 2 sites (racks) with several dozens of servers at each >> accessing a NAS (let's call it a NAS, although it's an IBM v7000 Unified >> that serves the files via NFS). >> >> The biggest problem is that it works active-passive, i.e. we always >> access one of the storages for read/write >> and the other one is replicated once every few hours, so it's more for >> backup needs. >> >> In this setup once the power goes down in our main site - we're stuck >> with a bit (several hours) outdated files >> and we need to remount all of the servers and what not. >> >> The multi site ceph was supposed to solve this problem for us. This way >> we would have only local mounts, i.e. >> each server would only access the filesystem that is in the same site. >> And if one of the sited go down - no pain. >> >> The files are rather small, pdfs and xml of 50-300KB mostly. >> The total size is about 25 TB right now. >> >> We're a low budget company, so your advise about developing is not going >> to happen as we have no such skills or resources for this. >> Plus, I want to make this transparent for the devs and everyone - just an >> infrastructure replacement that will buy me all of the ceph benefits and >> allow the company to survive the power outages or storage crashes. >> >> >> >> On Mon, May 21, 2018 at 5:12 PM, David Turner <drakonst...@gmail.com> >> wrote: >> >>> Not a lot of people use object storage multi-site. I doubt anyone is >>> using this like you are. In theory it would work, but even if somebody has >>> this setup running, it's almost impossible to tell if it would work for >>> your needs and use case. You really should try it out for yourself to see >>> if it works to your needs. And if you feel so inclined, report back here >>> with how it worked. >>> >>> If you're asking for advice, why do you need a networked posix >>> filesystem? Unless you are using proprietary software with this >>> requirement, it's generally lazy coding that requires a mounted filesystem >>> like this and you should aim towards using object storage instead without >>> any sort of NFS layer. It's a little more work for the developers, but is >>> drastically simpler to support and manage. >>> >>> On Mon, May 21, 2018 at 10:06 AM Up Safe <upands...@gmail.com> wrote: >>> >>>> guys, >>>> please tell me if I'm in the right direction. >>>> If ceph object storage can be set up in multi site configuration, >>>> and I add ganesha (which to my understanding is an "adapter" >>>> that serves s3 objects via nfs to clients) - >>>> won't this work as active-active? >>>> >>>> >>>> Thanks >>>> >>>> On Mon, May 21, 2018 at 11:48 AM, Up Safe <upands...@gmail.com> wrote: >>>> >>>>> ok, thanks. >>>>> but it seems to me that having pool replicas spread over sites is a >>>>> bit too risky performance wise. >>>>> how about ganesha? will it work with cephfs and multi site setup? >>>>> >>>>> I was previously reading about rgw with ganesha and it was full of >>>>> limitations. >>>>> with cephfs - there is only one and one I can live with. >>>>> >>>>> Will it work? >>>>> >>>>> >>>>> On Mon, May 21, 2018 at 10:57 AM, Adrian Saul < >>>>> adrian.s...@tpgtelecom.com.au> wrote: >>>>> >>>>>> >>>>>> >>>>>> We run CephFS in a limited fashion in a stretched cluster of about >>>>>> 40km with redundant 10G fibre between sites – link latency is in the >>>>>> order >>>>>> of 1-2ms. Performance is reasonable for our usage but is noticeably >>>>>> slower >>>>>> than comparable local ceph based RBD shares. >>>>>> >>>>>> >>>>>> >>>>>> Essentially we just setup the ceph pools behind cephFS to have >>>>>> replicas on each site. To export it we are simply using Linux kernel NFS >>>>>> and it gets exported from 4 hosts that act as CephFS clients. Those 4 >>>>>> hosts are then setup in an DNS record that resolves to all 4 IPs, and we >>>>>> then use automount to do automatic mounting and host failover on the NFS >>>>>> clients. Automount takes care of finding the quickest and available NFS >>>>>> server. >>>>>> >>>>>> >>>>>> >>>>>> I stress this is a limited setup that we use for some fairly light >>>>>> duty, but we are looking to move things like user home directories onto >>>>>> this. YMMV. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> *From:* ceph-users [mailto:ceph-users-boun...@lists.ceph.com] *On >>>>>> Behalf Of *Up Safe >>>>>> *Sent:* Monday, 21 May 2018 5:36 PM >>>>>> *To:* David Turner <drakonst...@gmail.com> >>>>>> *Cc:* ceph-users <ceph-users@lists.ceph.com> >>>>>> *Subject:* Re: [ceph-users] multi site with cephfs >>>>>> >>>>>> >>>>>> >>>>>> Hi, >>>>>> >>>>>> can you be a bit more specific? >>>>>> >>>>>> I need to understand whether this is doable at all. >>>>>> >>>>>> Other options would be using ganesha, but I understand it's very >>>>>> limited on NFS; >>>>>> >>>>>> or start looking at gluster. >>>>>> >>>>>> >>>>>> >>>>>> Basically, I need the multi site option, i.e. active-active >>>>>> read-write. >>>>>> >>>>>> >>>>>> >>>>>> Thanks >>>>>> >>>>>> >>>>>> >>>>>> On Wed, May 16, 2018 at 5:50 PM, David Turner <drakonst...@gmail.com> >>>>>> wrote: >>>>>> >>>>>> Object storage multi-site is very specific to using object storage. >>>>>> It uses the RGW API's to sync s3 uploads between each site. For CephFS >>>>>> you >>>>>> might be able to do a sync of the rados pools, but I don't think that's >>>>>> actually a thing yet. RBD mirror is also a layer on top of things to >>>>>> sync >>>>>> between sites. Basically I think you need to do something on top of the >>>>>> Filesystem as opposed to within Ceph to sync it between sites. >>>>>> >>>>>> >>>>>> >>>>>> On Wed, May 16, 2018 at 9:51 AM Up Safe <upands...@gmail.com> wrote: >>>>>> >>>>>> But this is not the question here. >>>>>> >>>>>> The question is whether I can configure multi site for CephFS. >>>>>> >>>>>> Will I be able to do so by following the guide to set up the multi >>>>>> site for object storage? >>>>>> >>>>>> >>>>>> >>>>>> Thanks >>>>>> >>>>>> >>>>>> >>>>>> On Wed, May 16, 2018, 16:45 John Hearns <hear...@googlemail.com> >>>>>> wrote: >>>>>> >>>>>> The answer given at the seminar yesterday was that a practical limit >>>>>> was around 60km. >>>>>> >>>>>> I don't think 100km is that much longer. I defer to the experts here. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> On 16 May 2018 at 15:24, Up Safe <upands...@gmail.com> wrote: >>>>>> >>>>>> Hi, >>>>>> >>>>>> >>>>>> >>>>>> About a 100 km. >>>>>> >>>>>> I have a 2-4ms latency between them. >>>>>> >>>>>> >>>>>> >>>>>> Leon >>>>>> >>>>>> >>>>>> >>>>>> On Wed, May 16, 2018, 16:13 John Hearns <hear...@googlemail.com> >>>>>> wrote: >>>>>> >>>>>> Leon, >>>>>> >>>>>> I was at a Lenovo/SuSE seminar yesterday and asked a similar question >>>>>> regarding separated sites. >>>>>> >>>>>> How far apart are these two geographical locations? It does matter. >>>>>> >>>>>> >>>>>> >>>>>> On 16 May 2018 at 15:07, Up Safe <upands...@gmail.com> wrote: >>>>>> >>>>>> Hi, >>>>>> >>>>>> I'm trying to build a multi site setup. >>>>>> >>>>>> But the only guides I've found on the net were about building it with >>>>>> object storage or rbd. >>>>>> >>>>>> What I need is cephfs. >>>>>> >>>>>> I.e. I need to have 2 synced file storages at 2 geographical >>>>>> locations. >>>>>> >>>>>> Is this possible? >>>>>> >>>>>> Also, if I understand correctly - cephfs is just a component on top >>>>>> of the object storage. >>>>>> >>>>>> Following this logic - it should be possible, right? >>>>>> >>>>>> Or am I totally off here? >>>>>> >>>>>> Thanks, >>>>>> >>>>>> Leon >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> ceph-users mailing list >>>>>> ceph-users@lists.ceph.com >>>>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>>>>> >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> ceph-users mailing list >>>>>> ceph-users@lists.ceph.com >>>>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>>>>> >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> ceph-users mailing list >>>>>> ceph-users@lists.ceph.com >>>>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>>>>> >>>>>> _______________________________________________ >>>>>> ceph-users mailing list >>>>>> ceph-users@lists.ceph.com >>>>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>>>>> >>>>>> >>>>>> Confidentiality: This email and any attachments are confidential and >>>>>> may be subject to copyright, legal or some other professional privilege. >>>>>> They are intended solely for the attention and use of the named >>>>>> addressee(s). They may only be copied, distributed or disclosed with the >>>>>> consent of the copyright owner. If you have received this email by >>>>>> mistake >>>>>> or by breach of the confidentiality clause, please notify the sender >>>>>> immediately by return email and delete or destroy all copies of the >>>>>> email. >>>>>> Any confidentiality, privilege or copyright is not waived or lost because >>>>>> this email has been sent to you by mistake. >>>>>> >>>>> >>>>> >>>> >> >> _______________________________________________ >> ceph-users mailing list >> ceph-users@lists.ceph.com >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >> >
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