I have 4 Samsung 840 Pro SSDs running in hardware RAID on an Intel RS2BL080 LSI RAID card. My read and write times are incredible:
$ dd bs=1M count=10000 if=/dev/zero of=test.img conv=fdatasync
10000+0 records in
10000+0 records out 10485760000 bytes (10 GB) copied, 6.3633 s, 1.6 GB/s
Read times are at about 2.0GB/s.
However, when I try duplicating a local file, I'll see my write speed drop to around 200MB/s. What could be going wrong here?
Here is my RAID card configuration, perhaps I misconfigured something? Any one of these drives can get >450MB/s write speed, I've seen it before while not using RAID.
Update
##Update##
InterestinglyInterestingly enough, I've found that some of these limitations have to do with the filesystem. ext4
starts out fast and slows down to a rate of about 230MB/s. btrfs
however, only slowed to about 830MB/s. ntfs
was slow like ext4
. Are there configuration options for ext4
to speed it up?