I just bought a fast Intel series 520 SSD (240 GB, 550 MBytes/sec) to replace my slower series 320 SSD (120 GB, 250MBytes/sec). I was expecting the speed when reading the ssd to jump from my current read speeds of around 250 MBytes/sec to (hopefully) something at least twice that speed. The specs say the 520 does 550 MBytes/sec for read and almost that for write. To my surprise the series 520 was only ~130 MBytes/sec. This is observed under Fedora-17 using "dd if=/dev/sdb2 of=/dev/null bs=64k count=1000". The board is an older Asus M3A78T and has been happily running the 320 at full rated speed for 1.5 years. Intel series 320: dd if=/dev/sda2 of=/dev/null bs=64K count=1000 1000+0 records in 1000+0 records out 65536000 bytes (66 MB) copied, 0.254144 s, 258 MB/s Intel series 520: dd if=/dev/sdb2 of=/dev/null bs=64K count=1000 1000+0 records in 1000+0 records out 65536000 bytes (66 MB) copied, 0.494915 s, 132 MB/s These number stay relatively constant, no matter how many seconds of transfer I do. Ditto for changing block size (bs=...) up to 1MByte. I see these numbers for the 520 when I attach it on the same SATA 3Gbit/sec link as the 320 or if I attach it on a new SATA 6Gbit/sec controller (Highpoint Rocket 620, a Marvel 88SE9125 PCIe SATA 6.0 Gb/s controller). I do see it attach at 3 Gbit/sec on the old controller and 6 Gbit/sec on the new controller. (So it isn't going down to SATA-1 speeds as far as the printf's I can see indicate.) Is the 520 defective? Ideas? The reviews of the 520 all show it really truly doing > 500MBytes/sec. These suckers can really fly. Just not for me... Google searches show that some folks running MS software have had similar problems and they managed to fix things by downgrading their BIOS setting to use IDE settings for the SSD. Other hits mentioned something about power management on the SATA being the culprit and IDE drivers nailed the power on instead of letting it flap in the wind. Is this something I can turn off from userland without recompiling the kernel? -wolfgang -- g+: https://plus.google.com/114566345864337108516/about -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
