View Full Version : Default File System for / in Azure

08-Jan-2019, 15:35
So somewhat new to the SUSE world and BTRFS. I deployed the following in Azure "SUSE Linux Enterprise Server 12 SP4 for SAP Applications x86_64 (64-bit)" and noticed XFS is used for everything. I was wondering why over what is normally BTRFS from what I've seen? Is XFS almost always used for SAP system on SUSE?

~> cat /etc/fstab
UUID=5e23c8a8-7fee-4a21-9904-1eeeb9a39c70 / xfs defaults 1 1
UUID=7251233a-4930-44bd-b581-c1dbd6fcd60f /boot xfs defaults 0 0

08-Jan-2019, 16:00
One of the key features of btrfs is the snapshot and roll back capability. However in a Cloud framework, Azure, EC2, GCE, OpenStack, root volumes are generally small and snapshots are generally taken externally, i.e. tooling provided by the framework. Given a small root volume snapshots internal to the filesystem, such as the btrfs snapshots, take up space that on a percentage basis is more valuable than on a physical server where the root volume may be 100 or more GB. Further, while in Azure and many other frameworks the boot menu can now be accessed via serial console that implies that GRUB boot timeout has to be set to a sufficient amount of time to get there, probably on the order of 45 seconds or more. This implies that every boot would be delayed by that amount of time whether one wants to boot into a previous snapshot or not. The btrfs feature of internal snapshot and roll back is more or less superseded by the features provided by the Cloud framework.

14-Jan-2019, 15:03
Thanks, that is a helpful explanation. Most on premise solutions we use also have snapshot based backups and not bare metal installs. Sounds like the recommendation is to not use BTRFS if that type of backup is available which is somewhat interesting. Understand the issue with access to the boot loader. An interesting thing to think about related to depending on the cloud architecture for the backups/rollbacks/snapshots is there are still limitations with the technologies available. For example, Azure Backup cannot support anything with a disk >1TB currently, which many SAP systems will obviously have.