[other] Hard drives very slow

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http://ubuntuforums.org – I have a number of drives that are acting very weird. There are 7x Seagate Barricuda 2TB 5900 RPM hard drives and 1 WD 750 GB Black. They are currently in a SAS-to-SATA expander, connected to an LSI raid card. They used to each get at least 100 MB/s read/write speeds. For the last few weeks the read/write speed has dropped to 10 MB/s or less. The speed stays the same under Ubuntu 12.04 (live USB), Linux Mint 13 (SSD), Windows 7 and Windows Server 2008. The speed stays the same after complete formats, and under multiple file systems. The speed stays the same if they are in the exp (Hardware)