Re: read only access on 1 LUN for multiple initiators
Remember that clients (especially Linux) doe cache blocks locally Doesn't kernel refresh the read cache for blocks at some intervals? If I make a new file on target locally, and waiting for sometime, hitting read command like ls on initiator side will read data from block device, not from stale cache, so that I can read updated data. I believed that this is how the file-system is supposed to work, but it is not? they do not invalidate that cache. Clients not invalidating cache means that they do not update their read cahce unless the volume is remounted? 2010/3/1, Ulrich Windl ulrich.wi...@rz.uni-regensburg.de: On 27 Feb 2010 at 0:23, Kapetanakis Giannis wrote: Hi, This probably have been brought up before, but I couldn't find any info. I'd like to setup multiple initiators (web/ftp cluster) to access read-only the same iscsi target. I would prefer to do this without cluster fs (ie GFS) if possible. However I want to have right access on the target server locally. I managed to do this but I have the following problem: When I write something on the target (locally on the server) the updates are not propagated to the initiators. Naturally, read-only media don't propagate changes, because they don't change. Remember that clients (especially Linux) doe cache blocks locally, and they do not invalidate that cache. So you could even experience application crashes when accessing data structures that were partially cached while being changed on the original. If I unmount and mount again I can see the changes. Naturally, because unmount invalidates the cached blocks for the device. Regards, Ulrich I'm sharing /dev/vg01/iscsi which is an ext3 fs. It's locally mounted on server and also mounted (/dev/sde - /mnt) on clients. Server is centos 5.4 scsi-target-utils-0.0-6.20091205snap.el5_4.1 target iqn.2008-09.com.example:server.target2 backing-store /dev/vg01/iscsi incominguser user pass initiator-address 10.0.0.0/26 write-cache off /target client is Fedora 12 iscsi-initiator-utils-6.2.0.870-10.fc12.1.x86_64 scsi22 : iSCSI Initiator over TCP/IP scsi 22:0:0:0: RAID IET Controller 0001 PQ: 0 ANSI: 5 scsi 22:0:0:0: Attached scsi generic sg5 type 12 scsi 22:0:0:1: Direct-Access IET VIRTUAL-DISK 0001 PQ: 0 ANSI: 5 sd 22:0:0:1: Attached scsi generic sg6 type 0 sd 22:0:0:1: [sde] 16777216 512-byte logical blocks: (8.58 GB/8.00 GiB) sd 22:0:0:1: [sde] Write Protect is off sd 22:0:0:1: [sde] Mode Sense: 79 00 00 08 sd 22:0:0:1: [sde] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA sde: unknown partition table sd 22:0:0:1: [sde] Attached SCSI disk kjournald starting. Commit interval 5 seconds EXT3-fs: mounted filesystem with ordered data mode. so is GFS the only option? Giannis -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-is...@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-is...@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-is...@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: read only access on 1 LUN for multiple initiators
Remember that clients (especially Linux) doe cache blocks locally Doesn't kernel refresh the read cache for blocks at some intervals? If I make a new file on target locally, and waiting for sometime, hitting read command like ls on initiator side will read data from block device, not from stale cache, so that I can read updated data. I believed that this is how the file-system is supposed to work, but it is not? they do not invalidate that cache. Clients not invalidating cache means that they do not update their read cahce unless the volume is remounted? Thanks. kim 2010/3/1, Ulrich Windl ulrich.wi...@rz.uni-regensburg.de: On 27 Feb 2010 at 0:23, Kapetanakis Giannis wrote: Hi, This probably have been brought up before, but I couldn't find any info. I'd like to setup multiple initiators (web/ftp cluster) to access read-only the same iscsi target. I would prefer to do this without cluster fs (ie GFS) if possible. However I want to have right access on the target server locally. I managed to do this but I have the following problem: When I write something on the target (locally on the server) the updates are not propagated to the initiators. Naturally, read-only media don't propagate changes, because they don't change. Remember that clients (especially Linux) doe cache blocks locally, and they do not invalidate that cache. So you could even experience application crashes when accessing data structures that were partially cached while being changed on the original. If I unmount and mount again I can see the changes. Naturally, because unmount invalidates the cached blocks for the device. Regards, Ulrich I'm sharing /dev/vg01/iscsi which is an ext3 fs. It's locally mounted on server and also mounted (/dev/sde - /mnt) on clients. Server is centos 5.4 scsi-target-utils-0.0-6.20091205snap.el5_4.1 target iqn.2008-09.com.example:server.target2 backing-store /dev/vg01/iscsi incominguser user pass initiator-address 10.0.0.0/26 write-cache off /target client is Fedora 12 iscsi-initiator-utils-6.2.0.870-10.fc12.1.x86_64 scsi22 : iSCSI Initiator over TCP/IP scsi 22:0:0:0: RAID IET Controller 0001 PQ: 0 ANSI: 5 scsi 22:0:0:0: Attached scsi generic sg5 type 12 scsi 22:0:0:1: Direct-Access IET VIRTUAL-DISK 0001 PQ: 0 ANSI: 5 sd 22:0:0:1: Attached scsi generic sg6 type 0 sd 22:0:0:1: [sde] 16777216 512-byte logical blocks: (8.58 GB/8.00 GiB) sd 22:0:0:1: [sde] Write Protect is off sd 22:0:0:1: [sde] Mode Sense: 79 00 00 08 sd 22:0:0:1: [sde] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA sde: unknown partition table sd 22:0:0:1: [sde] Attached SCSI disk kjournald starting. Commit interval 5 seconds EXT3-fs: mounted filesystem with ordered data mode. so is GFS the only option? Giannis -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-is...@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-is...@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-is...@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: read only access on 1 LUN for multiple initiators
so is GFS the only option? Is NFS an option? -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-is...@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: read only access on 1 LUN for multiple initiators
so is GFS the only option? Is NFS an option? -- Romeo Theriault -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-is...@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: read only access on 1 LUN for multiple initiators
On 27 Feb 2010 at 0:23, Kapetanakis Giannis wrote: Hi, This probably have been brought up before, but I couldn't find any info. I'd like to setup multiple initiators (web/ftp cluster) to access read-only the same iscsi target. I would prefer to do this without cluster fs (ie GFS) if possible. However I want to have right access on the target server locally. I managed to do this but I have the following problem: When I write something on the target (locally on the server) the updates are not propagated to the initiators. Naturally, read-only media don't propagate changes, because they don't change. Remember that clients (especially Linux) doe cache blocks locally, and they do not invalidate that cache. So you could even experience application crashes when accessing data structures that were partially cached while being changed on the original. If I unmount and mount again I can see the changes. Naturally, because unmount invalidates the cached blocks for the device. Regards, Ulrich I'm sharing /dev/vg01/iscsi which is an ext3 fs. It's locally mounted on server and also mounted (/dev/sde - /mnt) on clients. Server is centos 5.4 scsi-target-utils-0.0-6.20091205snap.el5_4.1 target iqn.2008-09.com.example:server.target2 backing-store /dev/vg01/iscsi incominguser user pass initiator-address 10.0.0.0/26 write-cache off /target client is Fedora 12 iscsi-initiator-utils-6.2.0.870-10.fc12.1.x86_64 scsi22 : iSCSI Initiator over TCP/IP scsi 22:0:0:0: RAID IET Controller 0001 PQ: 0 ANSI: 5 scsi 22:0:0:0: Attached scsi generic sg5 type 12 scsi 22:0:0:1: Direct-Access IET VIRTUAL-DISK 0001 PQ: 0 ANSI: 5 sd 22:0:0:1: Attached scsi generic sg6 type 0 sd 22:0:0:1: [sde] 16777216 512-byte logical blocks: (8.58 GB/8.00 GiB) sd 22:0:0:1: [sde] Write Protect is off sd 22:0:0:1: [sde] Mode Sense: 79 00 00 08 sd 22:0:0:1: [sde] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA sde: unknown partition table sd 22:0:0:1: [sde] Attached SCSI disk kjournald starting. Commit interval 5 seconds EXT3-fs: mounted filesystem with ordered data mode. so is GFS the only option? Giannis -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-is...@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-is...@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.
read only access on 1 LUN for multiple initiators
Hi, This probably have been brought up before, but I couldn't find any info. I'd like to setup multiple initiators (web/ftp cluster) to access read-only the same iscsi target. I would prefer to do this without cluster fs (ie GFS) if possible. However I want to have right access on the target server locally. I managed to do this but I have the following problem: When I write something on the target (locally on the server) the updates are not propagated to the initiators. If I unmount and mount again I can see the changes. I'm sharing /dev/vg01/iscsi which is an ext3 fs. It's locally mounted on server and also mounted (/dev/sde - /mnt) on clients. Server is centos 5.4 scsi-target-utils-0.0-6.20091205snap.el5_4.1 target iqn.2008-09.com.example:server.target2 backing-store /dev/vg01/iscsi incominguser user pass initiator-address 10.0.0.0/26 write-cache off /target client is Fedora 12 iscsi-initiator-utils-6.2.0.870-10.fc12.1.x86_64 scsi22 : iSCSI Initiator over TCP/IP scsi 22:0:0:0: RAID IET Controller 0001 PQ: 0 ANSI: 5 scsi 22:0:0:0: Attached scsi generic sg5 type 12 scsi 22:0:0:1: Direct-Access IET VIRTUAL-DISK 0001 PQ: 0 ANSI: 5 sd 22:0:0:1: Attached scsi generic sg6 type 0 sd 22:0:0:1: [sde] 16777216 512-byte logical blocks: (8.58 GB/8.00 GiB) sd 22:0:0:1: [sde] Write Protect is off sd 22:0:0:1: [sde] Mode Sense: 79 00 00 08 sd 22:0:0:1: [sde] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA sde: unknown partition table sd 22:0:0:1: [sde] Attached SCSI disk kjournald starting. Commit interval 5 seconds EXT3-fs: mounted filesystem with ordered data mode. so is GFS the only option? Giannis -- You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-is...@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.
