AHCI versus RST in Laptop

Last Modified: Thu, 20 Jul 2023 02:38:53 +0000 ; Created: Thu, 20 Jul 2023 02:38:53 +0000

Laptops in the last 5 years (2018-2023) include Intel RST support for fake-RAID or Optane configurations. Linux does not support the Intel RST found in laptops versus the much older RSTi implementations.

I benchmarked two NVMe SSDs in a Lenovo P1 Gen 3 laptop in multiple configuration modes to see what the performance was like.

Mode	Drive	Q	READ (MB/s)	WRITE (MB/s)
AHCI	C	SEQ1M Q8T1	3280	2538
AHCI	C	SEQ1M Q1T1	2119	1745
AHCI	C	RND4K Q32T1	305	304
AHCI	C	RND4K Q1T1	35	95
AHCI	D	SEQ1M Q8T1	3504	2011
AHCI	D	SEQ1M Q1T1	2315	1727
AHCI	D	RND4K Q32T1	323	330
AHCI	D	RND4K Q1T1	44	98
RST	C	SEQ1M Q8T1	3101	2187
RST	C	SEQ1M Q1T1	2088	1583
RST	C	RND4K Q32T1	269	313
RST	C	RND4K Q1T1	35	101
RST	D	SEQ1M Q8T1	3546	2256
RST	D	SEQ1M Q1T1	2079	1860
RST	D	RND4K Q32T1	275	310
RST	D	RND4K Q1T1	40	103
RST	RAID0	SEQ1M Q8T1	3195	3217
RST	RAID0	SEQ1M Q1T1	2303	1889
RST	RAID0	RND4K Q32T1	235	252
RST	RAID0	RND4K Q1T1	41	85

Conclusion

There was not a significant difference in performance for NVMe PCIe storage devices even in RAID0 stripe mode. The addition of an Intel RST driver could make installation more complicated although the Windows 10 installer did recogonize the disk volumes without help. There could be battery life impacts for the RST mode instead, but this was not tested.