HP SATA SSD vs SAS HDD

[NotmenHK]

Hi All,

I just got a HP DL380Gen9 server with 2x SATA SSD 120GB (D drive), and 2x SAS 300GB HDD (C drive) . Both raid 1.

SSD: HP 120GB 6G SATA VE 2.5in SC EV G1 SSD

SAS HDD: HP 300GB 6G SAS 15K 2.5in SC ENT HDD

Installed Windows 2008 R2 Enterprise through intelligent provionsing tools. (hope all drivers are updated).

Just run some HDD benchmark tools. And found that SAS HDD is faster than SSD HDD....... Attached the results....

Any suggest about the odd result? Or this is the fact?

Thanks.

Notmen

[Charlie K. (PL)]

Impossible :)

Don't you have Smart Cache software functionality enabled maybe ? It seemes to be some cache (PCIe NVME cache ?) acceleration active for SAS. Because results of SAS are totally inproper considering that technology.

Disable all cachings, then make tests with long period of time and big packages of data.

Regards / Charlie K.

[NotmenHK]

Chalie you are right. after I disable the cache on SAS dirve, the result is totally different.

Attached some results.

But with the cache enabled, the performance of SAS drive is very close to SSD drive in normal situation.

SSD performance is stable, even in extreme case, like random read/write 16Gbi data. While SAS drive performance will drop in this case, even the cache is enabled.

I expect SSD should out perform alot than SAS drive. Maybe SAS SSD or M.2 SSD will be much faster.

Thanks,

Notmen

[Charlie K. (PL)]

The truth is when you read or write as big as 16GB data. Compare Crystal results then at SAS RAID-1 with results of 100MB. See the difference ? With 100MB or even 1GB - you just measured cache speed, not disk speed :) SSD please notice - even with bigger part of data is stable and gives constantly high transfer results.

Second advantage of SSD - SSD has got 100 times smaller access time, so seeking data with SSD vs seeking data with SAS drives is 2-5 times faster. These are my personal observations.

And for tests - just use SSD in PCI Express technologi (NVMe). Then you will see what "devil" results mean ;D  NVMe SSDs are 2-4 times faster then regular "fast" SATA SSDs.