> 2024年6月18日 16:47，Benjamin Block <bblock@xxxxxxxxxxxxx> 写道： > > 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? I have explained it in other emails, you can read them. Thanks, Li > >>>> 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
