On Tue, Jun 18, 2024 at 11:06:13AM +0800, Li Feng wrote: > > 2024年6月18日 00:26，Benjamin Block <bblock@xxxxxxxxxxxxx> 写道： > > On Sat, Jun 15, 2024 at 12:03:47AM +0800, Li Feng wrote: > >> There is a scenario where a large number of discard commands > >> are issued when the iscsi initiator connects to the target > >> and then performs a session rescan operation. > > > > Is this with just one specific target implementation? This sounds like a > > broken/buggy target, or is there a reason why this happens in general? > > > > And broken target sounds like device quirk, rather than impacting every > > possible target. > > This is a common problem. Before sending a rescan, discard has been > negotiated to UNMAP. After the rescan, there will be a short window for > it to become WS16, and then it will immediately become UNMAP. > However, during this period, a small amount of discard commands > may become WS16, resulting in a strange problem. Ok, interesting. Do you know why this short window happens? > >> There is a time > >> window, most of the commands are in UNMAP mode, and some > >> discard commands become WRITE SAME with UNMAP. > >> > >> The discard mode has been negotiated during the SCSI probe. If > >> the mode is temporarily changed from UNMAP to WRITE SAME with > >> UNMAP, IO ERROR may occur because the target may not implement > >> WRITE SAME with UNMAP. Keep the discard mode stable to fix this > >> issue. > >> > >> Signed-off-by: Li Feng <fengli@xxxxxxxxxx> > >> --- -- Best Regards, Benjamin Block / Linux on IBM Z Kernel Development IBM Deutschland Research & Development GmbH / https://www.ibm.com/privacy Vors. Aufs.-R.: Wolfgang Wendt / Geschäftsführung: David Faller Sitz der Ges.: Böblingen / Registergericht: AmtsG Stuttgart, HRB 243294
