> > Meanwhile i narrow it down to a iscsi-target problem. Doing strace i saw > > it requires exclusive open. So solve it it created an sort of an > > hack.. :) > > Ok, you cannot have local services and remote services accessing > the same raw data sectors at the same time. > > I expressedly made blockio open the device exclusively to avoid > just what you are trying to do. Why? Did you have any problems in this scenario? Using blockio iscsi-target does not use any cache, right? > If you really need access to the iSCSI target locally, then > you will need to install an iSCSI initiator on the server and > connect to the target and use the new disk volume that is > created. Ok.. and is the following scenario workable? HP package cluster with MSA500 (basically 2 servers connected to a scsi shared storage) both servers export the same msa500 volume on clients i use iscsi-initiator + multipath to support the failure of one server In this scenario there are two iscsi-target server accessing the same data but on different machines. Basically it's the same thing as another process accessing the exported volume... Do you agree? > > from hdb and using device-mapper i create a linear mapping to 2 devices: > > > > hdb-int > > hdb-ext > > > > Next i put hdb-ext in ietd.conf and hdb-int in lvm.conf. iscsi-target > > still opens in exclusive mode but it only opens hdb-ext device. > > clvmd uses hdb-int that has no exclusive lock. > > You are heading down a path here that is fully unsupported and > discouraged, if you loose your data it will be completely and > totally because of this. :( > > Another way that we rejected is to put "gray" machine exporting the iscsi > > volume to it self also and using that device in clvmd. This option also > > worked but has less performance as all local contend has to be encoded to > > iscsi and decoded in the same machine. > > iSCSI encoding/decoding is minimal and if you are using a loopback > to connect should be as fast as the machine can do it. Do not try > this with fileio unit types though or the page cache will deadlock > between iSCSI target/initiator. IMHO encoding and decoding it locally would be a performance penalty that would not be required.. I dind't used fileio exactly because it caches content. > > The problem of iscsi-target opening the device excluse remais. > > And it will continue to remain. > > Why not try to explain what it is your are trying to accomplish > and a valid solution or two can be given. What i'm trying to do is the following: 2 servers connected to msa500 exporting a volume through iscsi-target 6 servers with iscsi-initiator + multipath accessing the volume all 8 servers with clvmd accessing the volume so i can create LVs in any of the 8 servers. The LVs are to be used by Xen virtual machines in any machine in the cluster I didn't want to use iscsi-target + iscsi-initiator on the msa connected machines as it would be a performance penalty. Thanks, Nuno Fernandes -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
