On Thu, Mar 8, 2018 at 11:59 AM, Lazuardi Nasution <mrxlazuardin@xxxxxxxxx> wrote: > Hi Mike, > > Since I have moved from LIO to TGT, I can do full ALUA (active/active) of > multiple gateways. Of course I have to disable any write back cache at any > level (RBD cache and TGT cache). It seem to be safe to disable exclusive > lock since each RBD image is accessed only by single client and as long as I > know mostly ALUA use RR of I/O path. How do you figure that's safe for preventing an overwrite with old data in an active/active path hiccup? > Best regards, > > On Mar 8, 2018 11:54 PM, "Mike Christie" <mchristi@xxxxxxxxxx> wrote: >> >> On 03/07/2018 09:24 AM, shadow_lin wrote: >> > Hi Christie, >> > Is it safe to use active/passive multipath with krbd with exclusive lock >> > for lio/tgt/scst/tcmu? >> >> No. We tried to use lio and krbd initially, but there is a issue where >> IO might get stuck in the target/block layer and get executed after new >> IO. So for lio, tgt and tcmu it is not safe as is right now. We could >> add some code tcmu's file_example handler which can be used with krbd so >> it works like the rbd one. >> >> I do know enough about SCST right now. >> >> >> > Is it safe to use active/active multipath If use suse kernel with >> > target_core_rbd? >> > Thanks. >> > >> > 2018-03-07 >> > ------------------------------------------------------------------------ >> > shadowlin >> > >> > ------------------------------------------------------------------------ >> > >> > *发件人：*Mike Christie <mchristi@xxxxxxxxxx> >> > *发送时间：*2018-03-07 03:51 >> > *主题：*Re: iSCSI Multipath (Load Balancing) vs RBD >> > Exclusive Lock >> > *收件人：*"Lazuardi Nasution"<mrxlazuardin@xxxxxxxxx>,"Ceph >> > Users"<ceph-users@xxxxxxxxxxxxxx> >> > *抄送：* >> > >> > On 03/06/2018 01:17 PM, Lazuardi Nasution wrote: >> > > Hi, >> > > >> > > I want to do load balanced multipathing (multiple iSCSI >> > gateway/exporter >> > > nodes) of iSCSI backed with RBD images. Should I disable exclusive >> > lock >> > > feature? What if I don't disable that feature? I'm using TGT >> > (manual >> > > way) since I get so many CPU stuck error messages when I was using >> > LIO. >> > > >> > >> > You are using LIO/TGT with krbd right? >> > >> > You cannot or shouldn't do active/active multipathing. If you have >> > the >> > lock enabled then it bounces between paths for each IO and will be >> > slow. >> > If you do not have it enabled then you can end up with stale IO >> > overwriting current data. >> > >> > >> > >> > >> > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > -- Jason _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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