Re: Block device naming

[Alibek Amaev]

Is there really no comment or suggestions how to avoid server failure
when changing the LUN number?


On Thu, May 9, 2019 at 11:43 PM Alibek A. <alibek.a@xxxxxxxxx> wrote:
>
> Hi!
>
> I want to address the following problem:
> On the system with hot-attached new storage volume, such as FC-switch update configuration for connected FC-HBA on servers, linux kernel reorder block devices and change names of block devices. Becouse scsi-id, wwn-id and other is a symbol links to block device names than on change block device name change path to device.
> This causes the server to stop working.
>
> For example, on server present ZFS pool with attached device by scsi-id
> # zpool status
>   pool: pool
>  state: ONLINE
>   scan: scrub repaired 0 in 1h39m with 0 errors on Sun Oct  8 02:03:34 2017
> config:
>
>     NAME                                      STATE     READ WRITE CKSUM
>     pool                                      ONLINE       0     0     0
>       scsi-3600144f0c7a5bc61000058d3b96d001d  ONLINE       0     0     0
>
> Before export new block device from storage to hba, scsi-id have next path to device:
> /dev/disk/by-id/scsi-3600144f0c7a5bc61000058d3b96d001d -> ../../sdd
>
> When added new block device by FC-switch, FC-HBA kernel change block device names:
> /dev/disk/by-id/scsi-3600144f0c7a5bc61000058d3b96d001d -> ../../sdf
>
> and ZFS can't access to device until reboot (partprobe, zpool online -e pool scsi-3600144f0c7a5bc61000058d3b96d001d - may help or may not help)
>
> Is there any way to fix or change this behavior of the kernel?
>
> It may be more reasonable to immediately assign an unique persistent identifier of device and linking other identifiers with it?
>
>
> With regards, Alibek!
>