ZFS SLOG benchmark er på vei.

[siDDis]

http://freshbsd.org/commit/freebsd/r321928

 

 

MFC r320683: Add naive benchmark for SSDs in ZFS SLOG role.ZFS SLOGs have very specific access pattern with many cache flushes,which none of benchmarks I know can simulate.  Since SSD vendors rarelyspecify cache flush time, this measurement can be useful to explain whysome ZFS pools are slower then expected.  This test writes data chunksof different size followed by cache flush, alike to what ZFS SLOG does,and measures average time.To illustrate, here is result for 6 years old SATA Intel 710 Series SSD:Synchronous random writes:         0.5 kbytes:    138.3 usec/IO =      3.5 Mbytes/s           1 kbytes:    137.7 usec/IO =      7.1 Mbytes/s           2 kbytes:    151.1 usec/IO =     12.9 Mbytes/s           4 kbytes:    158.2 usec/IO =     24.7 Mbytes/s           8 kbytes:    175.6 usec/IO =     44.5 Mbytes/s          16 kbytes:    210.1 usec/IO =     74.4 Mbytes/s          32 kbytes:    274.2 usec/IO =    114.0 Mbytes/s          64 kbytes:    416.5 usec/IO =    150.1 Mbytes/s         128 kbytes:    776.6 usec/IO =    161.0 Mbytes/s         256 kbytes:   1503.1 usec/IO =    166.3 Mbytes/s         512 kbytes:   2968.7 usec/IO =    168.4 Mbytes/s        1024 kbytes:   5866.8 usec/IO =    170.5 Mbytes/s        2048 kbytes:  11696.6 usec/IO =    171.0 Mbytes/s        4096 kbytes:  23329.6 usec/IO =    171.5 Mbytes/s        8192 kbytes:  46779.5 usec/IO =    171.0 Mbytes/s, and much newer and supposedly much faster NVMe Samsung 950 PRO SSD:Synchronous random writes:         0.5 kbytes:   2092.9 usec/IO =      0.2 Mbytes/s           1 kbytes:   2013.1 usec/IO =      0.5 Mbytes/s           2 kbytes:   2014.8 usec/IO =      1.0 Mbytes/s           4 kbytes:   2090.7 usec/IO =      1.9 Mbytes/s           8 kbytes:   2044.5 usec/IO =      3.8 Mbytes/s          16 kbytes:   2084.8 usec/IO =      7.5 Mbytes/s          32 kbytes:   2137.1 usec/IO =     14.6 Mbytes/s          64 kbytes:   2173.4 usec/IO =     28.8 Mbytes/s         128 kbytes:   2923.9 usec/IO =     42.8 Mbytes/s         256 kbytes:   3085.3 usec/IO =     81.0 Mbytes/s         512 kbytes:   3112.2 usec/IO =    160.7 Mbytes/s        1024 kbytes:   2430.6 usec/IO =    411.4 Mbytes/s        2048 kbytes:   3788.9 usec/IO =    527.9 Mbytes/s        4096 kbytes:   6198.0 usec/IO =    645.4 Mbytes/s        8192 kbytes:  10764.9 usec/IO =    743.2 Mbytes/sWhile the first one obviously has maximal throughput limitations, thesecond one has so high cache flush latency (about 2 millisecond), thatit makes one almost useless in SLOG role, despite of its good throughputnumbers.  Power loss protection is out of scope of this test, but Isuspect it can be related.

 

 

Prakteksempel på hvor treig "bånnmodellen" Samsung 960 Pro er.

[Nizzen]

http://freshbsd.org/commit/freebsd/r321928

 

 

MFC r320683: Add naive benchmark for SSDs in ZFS SLOG role.ZFS SLOGs have very specific access pattern with many cache flushes,which none of benchmarks I know can simulate.  Since SSD vendors rarelyspecify cache flush time, this measurement can be useful to explain whysome ZFS pools are slower then expected.  This test writes data chunksof different size followed by cache flush, alike to what ZFS SLOG does,and measures average time.To illustrate, here is result for 6 years old SATA Intel 710 Series SSD:Synchronous random writes:         0.5 kbytes:    138.3 usec/IO =      3.5 Mbytes/s           1 kbytes:    137.7 usec/IO =      7.1 Mbytes/s           2 kbytes:    151.1 usec/IO =     12.9 Mbytes/s           4 kbytes:    158.2 usec/IO =     24.7 Mbytes/s           8 kbytes:    175.6 usec/IO =     44.5 Mbytes/s          16 kbytes:    210.1 usec/IO =     74.4 Mbytes/s          32 kbytes:    274.2 usec/IO =    114.0 Mbytes/s          64 kbytes:    416.5 usec/IO =    150.1 Mbytes/s         128 kbytes:    776.6 usec/IO =    161.0 Mbytes/s         256 kbytes:   1503.1 usec/IO =    166.3 Mbytes/s         512 kbytes:   2968.7 usec/IO =    168.4 Mbytes/s        1024 kbytes:   5866.8 usec/IO =    170.5 Mbytes/s        2048 kbytes:  11696.6 usec/IO =    171.0 Mbytes/s        4096 kbytes:  23329.6 usec/IO =    171.5 Mbytes/s        8192 kbytes:  46779.5 usec/IO =    171.0 Mbytes/s, and much newer and supposedly much faster NVMe Samsung 950 PRO SSD:Synchronous random writes:         0.5 kbytes:   2092.9 usec/IO =      0.2 Mbytes/s           1 kbytes:   2013.1 usec/IO =      0.5 Mbytes/s           2 kbytes:   2014.8 usec/IO =      1.0 Mbytes/s           4 kbytes:   2090.7 usec/IO =      1.9 Mbytes/s           8 kbytes:   2044.5 usec/IO =      3.8 Mbytes/s          16 kbytes:   2084.8 usec/IO =      7.5 Mbytes/s          32 kbytes:   2137.1 usec/IO =     14.6 Mbytes/s          64 kbytes:   2173.4 usec/IO =     28.8 Mbytes/s         128 kbytes:   2923.9 usec/IO =     42.8 Mbytes/s         256 kbytes:   3085.3 usec/IO =     81.0 Mbytes/s         512 kbytes:   3112.2 usec/IO =    160.7 Mbytes/s        1024 kbytes:   2430.6 usec/IO =    411.4 Mbytes/s        2048 kbytes:   3788.9 usec/IO =    527.9 Mbytes/s        4096 kbytes:   6198.0 usec/IO =    645.4 Mbytes/s        8192 kbytes:  10764.9 usec/IO =    743.2 Mbytes/sWhile the first one obviously has maximal throughput limitations, thesecond one has so high cache flush latency (about 2 millisecond), thatit makes one almost useless in SLOG role, despite of its good throughputnumbers.  Power loss protection is out of scope of this test, but Isuspect it can be related.

 

 

Prakteksempel på hvor treig "bånnmodellen" Samsung 960 Pro er.

Vel... de testet med 950....

 

Igjen, så kommer det ann på hva man skal bruke det til. 

 

En traktor er overlegen en ferrari bil i mange tilfeller, og omvendt