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Investigating Problems with Disks
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I've exhausted all my research on this, so I'm turning to the mind-hive for help. I have an 6TB RAID 5 array in an OWC Thunderbay enclosure, with Thunderbolt connection to my MacPro (which has 64GB RAM, and an internal SSD). There are four identical Toshiba 2TB drives, model DT01ACA200, which are the drives installed when I got the thing. I use this RAID to store photos, video and music. There are literally hundreds of thousands of files of these types, so I recognize I'll get a performance hit of some degree because of that. There is about 200GB free on the array, which again, I know will give me a performance hit. Write cache is enabled. No i/o errors reported on any drive. Drive is formatted HFS+.
I can usually sit and wait, but read speeds of 43 MB/s and write speeds of 27 MB/s? I can't believe there would be this level of degradation in speeds due to drive capacity, but I'm willing to be told that I need to clean the drive up. I'm using the latest version of SoftRAID XT 5.7.2, with the same version driver. By contrast, the internal SSD gets about 1500MB/s read/785MB/s write, and the USB3 attached Time Machine volume gets about 200/190 r/w.
HELP!!! What am I missing here?
TIA
dave
Posted : 08/12/2018 5:47 pm
That is what to expect when the volume gets that full.Not only are the drive limited to the slowest parts of the disks ,but they are likely very fragmented, causing the heads to seek all over the drive.
You can check if the disks are OK, by using SoftRAID to "verify disks" and see what throughput you are getting with Activity Monitor. Similarly, "validate" the volume and see what performance is available. (Should get >400MB/s)
A backup/restore will help performance. And delete some files so you have 15% free space, which is the recommended space available.
Posted : 10/12/2018 10:39 am
