On 6/7/23 08:55, Jianlin Lv wrote:
1. MegaRAID adapters associated with 24 local disks. The disks are named sequentially as "sda," "sdb," and so on, up to "sdx." 2. STAT controllers associated with the root disk, named "sdy." Both the MegaRAID adapters and the SATA controller (PCH) are accessed via the PCIe bus. In theory, depending on their PCIe bus ID in ascending order, the devices should be initialized in ascending order as well.
Hmm ... I don't think there is anything that prevents the PCIe maintainer from changing the PCIe probing behavior from synchronous to asynchronous? In other words, I don't think it is safe to assume that PCIe devices are always scanned in the same order.
For cloud deployment, the local volume provisioner detects and creates PVs for each local disk (from sda to sdx) on the host, and it cleans up the disks when they are released. This requires the logical names of the disks to be deterministic.
I see two possible solutions: - Change the volume provisioner such that it uses disk references that do not depend on the probing order, e.g. /dev/disk/by-id/... - Implement an algorithm in systemd that makes disk names predictable. An explanation of how predictable names work for network interfaces is available here: https://wiki.debian.org/NetworkInterfaceNames. The systemd documentation about predictable network names is available here: https://www.freedesktop.org/software/systemd/man/systemd.net-naming-scheme.html These alternatives have the advantage that disk scanning remains asynchronous. Thanks, Bart.
