Hi all,
Just read an interesting article in admin-magazine.com concerning raid and SSD's. According to the article controller write-back cache and controller read-ahead cache should be disabled. Disabling write-back cache gains 33% performance while disabling read-ahead cache gains 40% performance. Test was made with Intel DC S3500 and Avago (formerly LSI) Mega-RAID 9365. Performance wise mdadm based raid was on par with a raid controller.
Conclusion must be that if you only use SSD in your raid you gain very little by spending 400-600 $ on a raid controller and if you are limited in SATA ports stick to a HBA and spend the saved money on more SSD's.
Just read an interesting article in admin-magazine.com concerning raid and SSD's. According to the article controller write-back cache and controller read-ahead cache should be disabled. Disabling write-back cache gains 33% performance while disabling read-ahead cache gains 40% performance. Test was made with Intel DC S3500 and Avago (formerly LSI) Mega-RAID 9365. Performance wise mdadm based raid was on par with a raid controller.
Conclusion must be that if you only use SSD in your raid you gain very little by spending 400-600 $ on a raid controller and if you are limited in SATA ports stick to a HBA and spend the saved money on more SSD's.