General question on shared storage
Hi! I have a question for HA scenarios, where multiple hosts connect to a shared block device: AFAIK, Linux buffers blocks from block devices. So if host A reads a block from shared storage (e.g. the MBR), and later host B modifies that block, will host A still have the last block read in cache? If so there's a big problem. Consider that you want to mount a non-clustered filesystem alternatingly on two hosts (like for a HA failover). If host A used the filesystem, the host B took over the filesystem without booting host A, and later host A takes back the filesystem from host B, host A might have some obsolete blocks in its buffer. Does the application have to flush the buffers explicitly, and if so: Where on a multipath device (i.e. on every path or only on the multipath device)? Sorry, if that's not directly connected to iSCSI, but to shared block storage in general. Regards, Ulrich -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com. To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en.
Disk not ready-error while booting the Initiator
Hello, as the subject says, I have the problem that after I configured everything properly (the iscsi-disk is accessible from my initiator, can be mounted and files can even be copied to it) and then restart my Ubuntu-Initiator-PC I get the mentioned error on boot. More precisely, the error message says that the disk /storage is not accessible or ready (with /storage being my mounting point of the iscsi-disk). I have to press S every time I boot the PC and then manually mount the iscsi-disk, which then works perfectly normal again! Anyone knows what might be the cause of this problem??? -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com. To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en.
Re: Disk not ready-error while booting the Initiator
Hi Adnan, Can you give some more detail How you exactly mounting disk to your mount point(while rebooting the system). Did you list your iscsi device under /etc/fstab ? Regards, Manish On Tue, May 17, 2011 at 2:48 PM, Adnan Pasic pq...@yahoo.de wrote: Hello, as the subject says, I have the problem that after I configured everything properly (the iscsi-disk is accessible from my initiator, can be mounted and files can even be copied to it) and then restart my Ubuntu-Initiator-PC I get the mentioned error on boot. More precisely, the error message says that the disk /storage is not accessible or ready (with /storage being my mounting point of the iscsi-disk). I have to press S every time I boot the PC and then manually mount the iscsi-disk, which then works perfectly normal again! Anyone knows what might be the cause of this problem??? -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com. To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en. -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com. To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en.
Re: Disk not ready-error while booting the Initiator
Hello! thanks for your answer. Yes, indeed I have listed the device under fstab, as you can see here: /dev/sdb1 /srv/cloud/images_netdev 0 0 Shouldn't this be enough? Mounting the device by myself after the initiator has booted works without any flaws (sudo mount /dev/sdb1 /srv/cloud/images), but only the automatic mounting by boot doesn't work. I hope these informations are enough?? On 17 Mai, 15:17, manish singh tumbin1...@gmail.com wrote: Hi Adnan, Can you give some more detail How you exactly mounting disk to your mount point(while rebooting the system). Did you list your iscsi device under /etc/fstab ? Regards, Manish On Tue, May 17, 2011 at 2:48 PM, Adnan Pasic pq...@yahoo.de wrote: Hello, as the subject says, I have the problem that after I configured everything properly (the iscsi-disk is accessible from my initiator, can be mounted and files can even be copied to it) and then restart my Ubuntu-Initiator-PC I get the mentioned error on boot. More precisely, the error message says that the disk /storage is not accessible or ready (with /storage being my mounting point of the iscsi-disk). I have to press S every time I boot the PC and then manually mount the iscsi-disk, which then works perfectly normal again! Anyone knows what might be the cause of this problem??? -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com. To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en. -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com. To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en.
iscsiadm error
Hi All: Can anyone help? I installed open-iscsi in Slitaz and get the following error messages. root@slitaz:~# iscsiadm -m discovery -t sendtargets -p 192.168.1.6:3260 -d 7 iscsiadm: Max file limits 1024 1024 iscsiadm: can not connect to iSCSI daemon (111)! iscsiadm: Could not get config file for sync config iscsiadm: Looking for config file /etc/iscsi/send_targets/192.168.1.6,3260 iscsiadm: Looking for config file /etc/iscsi/send_targets/192.168.1.6,3260 config st_config. iscsiadm: Looking for config file /etc/iscsi/send_targets/192.168.1.6,3260 iscsiadm: iface_for_each_iface found iface.example iscsiadm: looking for iface conf /etc/iscsi/ifaces/iface.example iscsiadm: iface is not valid Iface settings [hw=,ip=,net_if=,iscsi_if=iface.example] iscsiadm: Could not scan /sys/class/iscsi_transport. iscsiadm: Could not scan /sys/class/iscsi_transport. iscsiadm: starting sendtargets discovery, address 192.168.1.6:3260, iscsiadm: can not connect to iSCSI daemon (111)! iscsiadm: Cannot perform discovery. Initiatorname required. iscsiadm: Discovery process to 192.168.1.6:3260 failed to create a discovery session. iscsiadm: Could not perform SendTargets discovery. Thanks! Hsuanyeh -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com. To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en.
Re: General question on shared storage
AFAIK, Linux buffers blocks from block devices. So if host A reads a block from shared storage (e.g. the MBR), and later host B modifies that block, will host A still have the last block read in cache? If so there's a big problem. I am only familiar with GFS and ASM, and both of those will typically disable any sort of caching. Consider that you want to mount a non-clustered filesystem alternatingly on two hosts (like for a HA failover). If host A used the filesystem, the host B took over the filesystem without booting I would recommend only logging in from one host at a time. Some SAN types (e.g. EqualLogic) will allow multiple hosts to discover the target, but will only allow one to be logged in. This will help with split brain corruption issues. In general, though, you should be careful of trying to force a SAN type of solution when you really need NAS. NFS and Samba are quite mature and easy to deal with. Mark -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com. To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en.
Re: Disk not ready-error while booting the Initiator
On 05/17/2011 04:18 AM, Adnan Pasic wrote: Hello, as the subject says, I have the problem that after I configured everything properly (the iscsi-disk is accessible from my initiator, can be mounted and files can even be copied to it) and then restart my Ubuntu-Initiator-PC I get the mentioned error on boot. More precisely, the error message says that the disk /storage is not accessible or ready (with /storage being my mounting point of the iscsi-disk). I have to press S every time I boot the PC and then manually mount the iscsi-disk, which then works perfectly normal again! I am not familiar with ubuntu. It might be that the network is not fully up when iscsi starts up. So when the auto mount code is run iscsi is not ready. I think if you use something like network manager this can happen a lot in older distros or distros not setup to handle that type of situation. When you get the not ready errors is that coming from mount or some sort of disk management app? What else is in /var/log/messages around that time? Any type of iscsi or network messages? Is the iscsi disk even set up at this time (can you see the iscsi/scsi disk setup messages in /var/log/messages)? -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com. To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en.
Re: iscsiadm error
On 05/17/2011 08:37 AM, Hsuan-Yeh Chang wrote: Hi All: Can anyone help? I installed open-iscsi in Slitaz and get the following error messages. Where did you get the open-iscsi programs? Were they from the distro or from open-iscsi.org/kernel.org? If the latter then I think the init scripts probably do not work for your distro. The problem below is caused by not having iscsid running and iscsi_tcp loaded. So before you run the discovery command do # modprobe iscsi_tcp # iscsid # iscsiadm -m discovery -t sendtargets -p 192.168.1.6:3260 root@slitaz:~# iscsiadm -m discovery -t sendtargets -p 192.168.1.6:3260 -d 7 iscsiadm: Max file limits 1024 1024 iscsiadm: can not connect to iSCSI daemon (111)! iscsiadm: Could not get config file for sync config iscsiadm: Looking for config file /etc/iscsi/send_targets/192.168.1.6,3260 iscsiadm: Looking for config file /etc/iscsi/send_targets/192.168.1.6,3260 config st_config. iscsiadm: Looking for config file /etc/iscsi/send_targets/192.168.1.6,3260 iscsiadm: iface_for_each_iface found iface.example iscsiadm: looking for iface conf /etc/iscsi/ifaces/iface.example iscsiadm: iface is not valid Iface settings [hw=,ip=,net_if=,iscsi_if=iface.example] iscsiadm: Could not scan /sys/class/iscsi_transport. iscsiadm: Could not scan /sys/class/iscsi_transport. iscsiadm: starting sendtargets discovery, address 192.168.1.6:3260, iscsiadm: can not connect to iSCSI daemon (111)! iscsiadm: Cannot perform discovery. Initiatorname required. iscsiadm: Discovery process to 192.168.1.6:3260 failed to create a discovery session. iscsiadm: Could not perform SendTargets discovery. Thanks! Hsuanyeh -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com. To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en.
