[DRBD-user] Getting TRIM to Work with DRBD

Lars Ellenberg lars.ellenberg at linbit.com
Mon Jul 24 11:46:26 CEST 2017

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Fri, Jul 21, 2017 at 06:21:15PM +0000, Eric Robinson wrote:
>Folks, does anyone know why trim does not show as enabled for drbd?
>The physical drives support it. The raid array supports it. I can trim non-drbd volumes just fine. But the drbd devices show trim as not supported.
># lsblk -D
>sda                0      512B       4G         1
>├─sda1             0      512B       4G         1
>│ └─md0            0      128K     256M         0
>├─sda2             0      512B       4G         1
>│ └─md1            0      128K     256M         0
>├─sda3             0      512B       4G         1
>├─sda4             0      512B       4G         1
>├─sda5             0      512B       4G         1
>│ └─md2            0      128K     256M         0
>│   └─drbd0        0        0B       0B         0          <-- Note: DISC-GRAN and DISC-MAX should be non-zero.
>I'm using drbd 9.0.1.

For DRBD 9, we will pretty much ignore any complaints against anything
older than "latest", which currently is 9.0.8.

The up-merge of the write-same and discard support from 8 to 9
was unfortunately broken in many ways.
It has just received yet an other fix (unrelated to your scenario,
related to the request size verification) even post 9.0.8.
So yes, it *will* help.

And no, you will not have any luck with 9.0.1. Not at all.
And not only for discards.

: Lars Ellenberg
: LINBIT | Keeping the Digital World Running
: DRBD -- Heartbeat -- Corosync -- Pacemaker

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