On 6 November 2012 01:32, James Sefton <james@xxxxxxxxxxxx> wrote: > Joseph Glanville <joseph.glanville@...> writes: > >> >> On 6 November 2012 00:15, James Sefton <james@...> wrote: >> > James Sefton <james@...> writes: >> > >> > Aha, I have more information. >> > >> > ls /dev/block -l >> > >> > <filtered results to relevant> >> > lrwxrwxrwx 1 root root 10 Nov 5 12:51 252:0 -> ../bcache0 >> > lrwxrwxrwx 1 root root 10 Nov 5 12:51 252:1 -> ../bcache1 >> > lrwxrwxrwx 1 root root 12 Nov 5 12:51 252:2 -> ../bcache1p1 >> > >> > >> > Our script does things in the following order: >> > 1. Registers bcache0 - OK >> > - links bcache0 in /dev/block/252:0 >> > 2. Registers bcache1 - OK >> > - links bcache1 in /dev/block/252:1 >> > 3. Partitions bcache1 - OK (single partition at the moment) >> > - links bcache1p1 in /dev/block/252:2 >> > 4. Partitions bcache0 - Partition table writes okay, but bcache0p1 does not > get >> > created. >> > - presumably attempts to link /dev/block/252:1 or something, and fails. >> > 5. Registers bcache2 - FAIL, prevents any further bcache devices being >> > registered and prevents system shut-down. >> > - attempts to link bcache2 in /dev/block/252:2, which is already used for >> > bcache1p1. >> > >> > Probably explains why this has not been seen before since we only just added >> > support for partitions with the patch details you recently gave me. >> > >> > Any chance of a patch to fix the numbering? >> > (I wish my C++ was up to scratch so that I could do it myself as it looks > like >> > it could be relatively simple!) >> > >> > Many Thanks, >> > >> > James >> > >> > >> > -- >> > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in >> > the body of a message to majordomo@... >> > More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> Though not a fix, a workaround could be to use LVM rather than partitions. >> >> LVM ontop of bcache works quite nicely you just need to add the >> following to /etc/lvm.conf >> >> types = [ "bcache", 16 ] >> >> Also check your filter line to ensure that /dev/bcacheX will be scanned as a > PV. >> >> Once you have done that you can create a volume group as usual: >> >> vgcreate vg0 /dev/bcache0 >> >> And then any number of LVs: >> >> lvcreate -n root -L50G vg0 >> >> In my opinion this is considerably better than partitions. >> >> Joseph. >> > > > Hi Joseph, > > Many thanks for the suggestion. > > I wish I could do that but the cache devices are being exposed to virtual > machines as virtual disks and so the clients could easily repartition them back > which would then reproduce the conflicting block device numbers. > > I am also not sure how well LVM might cope if the PV's (etc..) were detected > both in the host operating system and within a guest. > > Even if LVM could work - I would still need to be able to accommodate a client > the does not want LVM and chooses to repartition the device, and currently that > would break the host server. What kind of guests are these? If I am correct this is some sort of VPS environment, probably Xen or KVM? In that case if you pass through a logical volume and you properly adjust the filter in the host OS to only scan the bcache devices and not traverse recursively this works perfectly. The guest OS will be able to partition the logical volume and the guest will not be able the see the underlying volume group. > > I do really appreciate the suggestion though. > > Regards, > > James > > -- > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html Joseph. -- CTO | Orion Virtualisation Solutions | www.orionvm.com.au Phone: 1300 56 99 52 | Mobile: 0428 754 846 -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
