Re: [Linux-cluster] SCSI Reservations Red Hat Cluster Suite
Tomasz Sucharzewski napisał(a): Hello, Ryan O'Hara wrote: 4 - Limitations ... - Multipath devices are not currently supported. What is the reason - it is strongly required to use at least two HBA in a SAN network, which is useless when using scsi reservation. Hello, There is need to use multipath in production environments, and it is the main drawback of SCSI Reservations for Red Hat Cluster Suite. Here [1] You can read more about the problems with SCSI Reservations http://www.mail-archive.com/linux-cluster@redhat.com/msg00524.html Best Regards Maciej Bogucki -- Linux-cluster mailing list Linux-cluster@redhat.com https://www.redhat.com/mailman/listinfo/linux-cluster
Re: [Linux-cluster] SCSI Reservations Red Hat Cluster Suite
I believe that this is only a limitation for RHEL4. RHEL5 should have a fix that allows dm-multipath to properly pass ioctls to all devices. Hello, One problem is registration, but another problem is un-registration fe. when there is failover from one HBA to another and failback. Third problem is active-standby LB for two or more HBA, and how to handle this. Best Regards Maciej Bogucki -- Linux-cluster mailing list Linux-cluster@redhat.com https://www.redhat.com/mailman/listinfo/linux-cluster
Re: [Linux-cluster] SCSI Reservations Red Hat Cluster Suite
Nice overview. Wish I had this a few weeks ago :-) I am curious as to why LVM2 is required? With simple modification of the scsi_reserve (and maybe fence_scsi), using an msdos partitioned disk seems to work fine. This is only in testing but I haven't seen any issues as of yet. Ryan O'Hara wrote: Attached is the latest version of the Using SCSI Persistent Reservations with Red Hat Cluster Suite document for review. Feel free to send questions and comments. -Ryan -- Jeff Macfarland ([EMAIL PROTECTED]) Nexa Technologies - 972.747.8879 Systems Administrator GPG Key ID: 0x5F1CA61B GPG Key Server: hkp://wwwkeys.pgp.net -- Linux-cluster mailing list Linux-cluster@redhat.com https://www.redhat.com/mailman/listinfo/linux-cluster
Re: [Linux-cluster] SCSI Reservations Red Hat Cluster Suite
Hello, Ryan O'Hara wrote: 4 - Limitations ... - Multipath devices are not currently supported. What is the reason - it is strongly required to use at least two HBA in a SAN network, which is useless when using scsi reservation. Regards, Tomasz Sucharzewski On Fri, 28 Mar 2008 09:20:53 -0500 Ryan O'Hara [EMAIL PROTECTED] wrote: 4 - Limitations In addition to these requirements, fencing by way of SCSI persistent reservations also some limitations. - Multipath devices are not currently supported. -- Tomasz Sucharzewski [EMAIL PROTECTED] -- Linux-cluster mailing list Linux-cluster@redhat.com https://www.redhat.com/mailman/listinfo/linux-cluster
Re: [Linux-cluster] SCSI Reservations Red Hat Cluster Suite
On Fri, Mar 28, 2008 at 8:15 AM, Ryan O'Hara [EMAIL PROTECTED] wrote: The reason for the cluster LVM2 requirement is for device discovery. The scripts use LVM commands to find cluster volumes and then gets a list of devices that make up those volumes. Consider the alternative -- users would have to manually define a list of devices that need registrations/reservations. This would have to be defined on each node. What make this even more problematic is that each node may have different device names for shared storage devices (ie. what may be /deb/sdb on one node may be /deb/sdc on another). Furthermore, those device names could change between reboots. The general solution is to query clvmd for a list of cluster volumes and get a list of devices for those volumes. You can also use symbolic links under /dev/disk/by-id/ which are persistent across nodes/reboots. -Alex -- Linux-cluster mailing list Linux-cluster@redhat.com https://www.redhat.com/mailman/listinfo/linux-cluster
Re: [Linux-cluster] SCSI Reservations Red Hat Cluster Suite
True. Any solution for auto discovery? I've no problem with statically defining a device, but that would be pretty nice if possible. Alex Kompel wrote: On Fri, Mar 28, 2008 at 8:15 AM, Ryan O'Hara [EMAIL PROTECTED] wrote: The reason for the cluster LVM2 requirement is for device discovery. The scripts use LVM commands to find cluster volumes and then gets a list of devices that make up those volumes. Consider the alternative -- users would have to manually define a list of devices that need registrations/reservations. This would have to be defined on each node. What make this even more problematic is that each node may have different device names for shared storage devices (ie. what may be /deb/sdb on one node may be /deb/sdc on another). Furthermore, those device names could change between reboots. The general solution is to query clvmd for a list of cluster volumes and get a list of devices for those volumes. You can also use symbolic links under /dev/disk/by-id/ which are persistent across nodes/reboots. -Alex -- Linux-cluster mailing list Linux-cluster@redhat.com https://www.redhat.com/mailman/listinfo/linux-cluster ___ Inbound Email has been scanned by Nexa Technologies Email Security Systems. ___ -- Jeff Macfarland ([EMAIL PROTECTED]) Nexa Technologies - 972.747.8879 Systems Administrator GPG Key ID: 0x5F1CA61B GPG Key Server: hkp://wwwkeys.pgp.net -- Linux-cluster mailing list Linux-cluster@redhat.com https://www.redhat.com/mailman/listinfo/linux-cluster
