diff options
| author | Martin Schwenke <martin@meltin.net> | 2014-07-28 11:37:41 +1000 |
|---|---|---|
| committer | Martin Schwenke <martin@meltin.net> | 2014-07-28 11:37:41 +1000 |
| commit | 88d070962fa024e273ca0b1784f1ee738b70047f (patch) | |
| tree | b55feff6e7c4919f47d0589672a31d10ed2a8fee | |
| parent | d80bf18664677853232726284303014c890cfc4e (diff) | |
| download | autocluster-88d070962fa024e273ca0b1784f1ee738b70047f.tar.gz autocluster-88d070962fa024e273ca0b1784f1ee738b70047f.tar.xz autocluster-88d070962fa024e273ca0b1784f1ee738b70047f.zip | |
Default to virtio system disks
The qcow2 + virtio + writeback problem seems to be fixed.
Signed-off-by: Martin Schwenke <martin@meltin.net>
| -rw-r--r-- | README | 26 | ||||
| -rw-r--r-- | config.d/00base.defconf | 2 |
2 files changed, 20 insertions, 8 deletions
@@ -440,6 +440,19 @@ Keep it simple CTDB cluster. It is just extra node that can be used as a test client or similar. +Corrupt system disks +==================== + +Recent versions of KVM seem to have fixed problems where the +combination of qcow2 file format, virtio block devices and writeback +caching would cause result in corrupt. This means the default system +disk bus type (a.k.a. SYSTEM_DISK_TYPE) is now virtio. + +If using an older version of KVM or if you experience corruption of +the system disk, try using IDE system disks: + + SYSTEM_DISK_TYPE=ide + iSCSI shared disks ================== @@ -476,13 +489,12 @@ cluster will need to have a different setting for ISCSI_TID. Raw IDE system disks ==================== -RHEL versions of KVM do not support the SCSI block device emulation, -so autocluster now defaults to using an IDE system disk instead of a -SCSI one. Therefore, you can use virtio or ide system disks. -However, writeback caching, qcow2 and virtio are incompatible and -result in I/O corruption. So, you can use either virtio system disks -without any caching, accepting reduced performance, or you can use IDE -system disks with writeback caching, with nice performance. +Older RHEL versions of KVM did not support the SCSI block device +emulation, and produced corruption when virtio disks were used with +qcow2 disk images and writeback caching. In this case, you can use +either virtio system disks without any caching, accepting reduced +performance, or you can use IDE system disks with writeback caching, +with nice performance. For IDE disks, here are the required settings: diff --git a/config.d/00base.defconf b/config.d/00base.defconf index e380fa9..c93b456 100644 --- a/config.d/00base.defconf +++ b/config.d/00base.defconf @@ -77,7 +77,7 @@ defconf BASE_TEMPLATES "$installdir/base" \ defconf BASE_FORMAT "qcow2" \ "<fmt>" "format to use for the qemu base images" -defconf SYSTEM_DISK_TYPE "ide" \ +defconf SYSTEM_DISK_TYPE "virtio" \ "scsi|ide|virtio" "type of disks to use in nodes" rhel_disk_prefix () |