[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-users] Re: Xen + SAN
On Thu, Jun 23, 2011 at 4:04 PM, Shaun Reitan <mailinglists@xxxxxxxxxxxxxxxx> wrote: > I don't know about AOE but with ISCSI the problem I'm seeing is that if i > create a volume group on the SAN there is no way to export that volume > group. ÂI could export the device that the volume group was created on but > then the host doesn't see that VG. I'm assuming i would need to use > clustered LVM for that which i have been told to stay far away from. Another > option was to carve out the LV's on the SAN and to export each LV to the > initiators but still the problem is that the host assigns these luns to > /dev/sd devices and there's no simple nice way to map them to who owns what > disk. ÂLeast not that I've found yet. ÂI'm fairly new to ISCSI though so > maybe there's something I'm missing. your problem has two parts: A: the sharing/splitting. iSCSI shares block devices, and (as you've found) a VG is not a block device. you have to either export PVs or LVs there are three (main) ways to do it: 1: don't worry about partitions/LVM on the target. Export disks (or rather, arrays). On the initator(s) set those as PVs to create a VG and then LVs. typically you do it on only one initiator and then vgscan on all the others (like John Madden). pros: simple, manageable. cons: no lock protection, resizing LVs can be dangerous without suspending initiators. 2: do as 1, but use cLVM. any LVM management done on any initiator is automatically and atomically seen by all of them. pros: safer. cons: the lock manager itself is a big pain to manage. 3: do all the LVM management on the target(s), export each LV as an iSCSI LUN. Most commercial iSCSI appliances include management on par with LVM, at the very least. pros: much safer, easier to handle, no need of shared locks. cons: you can't have a LV spanning two targets. B: the Linux iSCSI initiator exposes each LUN as a full drive: /dev/sdd, /dev/sde, etc., not as a 'partition' /dev/sdX1, /dev/sdX2, etc. That's because they're exactly the same as SCSI disks. but, just like SCSI disks, those LUNs are partitionable with any tool. just do `parted /dev/sdX` and create a full-size /dev/sdX1 partition. (BTW, wasn't there an iSCSI-specific 'phy:' driver? something like 'phy:iscsi:<lun name>'.... or am i mixing faint memories?) -- Javier _______________________________________________ Xen-users mailing list Xen-users@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-users
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