# Re: \[PATCH 0/1\] RFC: Unreliable discard performance can cripple RAID1

- From: Martin K. Petersen \<hidden\>
- Date: 2015-06-25 01:05:07 
- List: linux-raid
- Page: https://ratatoskr.run/linux-raid/2015/06/6629938
- Thread: https://ratatoskr.run/linux-raid/2015/06/6629938/t.md

```text
>>>>> "Jes" == Jes Sorensen [ref] writes:

>> Or is this some non-SATA/SCSI SSD that has a 'make_request_fn'
>> driver?  I think I came across one of those before (NVMe).  In that
>> case - the driver needs to be fixed.

Jes> Nope the block layer doesn't merge the requests at this point.

Then something broke it. Discard merging used to work.

-- 
Martin K. Petersen	Oracle Linux Engineering
```