Hello, FYI I'm getting ~68MB/s on two intel330 in RAID1 aswell on vanilla 3.8.8 and 3.9.0-rc3 when writing random data and ~236MB/s writing from /dev/zero mdadm -C /dev/md0 -l 1 -n 2 --assume-clean --force --run /dev/sdb /dev/sdc openssl enc -aes-128-ctr -pass pass:"$(dd if=/dev/urandom bs=128 count=1 2>/dev/null | base64)" -nosalt < /dev/zero | pv -pterb > /run/fill ~1.06GB/s dd if=/run/fill of=/dev/null bs=1M count=1024 iflag=fullblock ~5.7GB/s dd if=/run/fill of=/dev/md0 bs=1M count=1024 oflag=direct ~68MB/s dd if=/dev/zero of=/dev/md0 bs=1M count=1024 oflag=direct ~236MB/s iostat claiming 100% util on both drives when doing so, running both deadline and noop scheduler, doing the same with 4 threads and offset by 1.1GB on the disk and taske set to 4 cores makes no difference, still ~68MB/s with random data # for x in `seq 0 4`; do taskset -c $x dd if=/run/fill of=/dev/md0 bs=1M count=1024 seek=$(($x * 1024)) oflag=direct & done /Tommy 2013/4/21 Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx>: > On 4/20/2013 6:26 PM, Andrei Banu wrote: > >> They are connected through SATA2 ports (this does explain the read speed >> but not the pitiful write one) in AHCI. > > These SSDs are capable of 500MB/s, and cost ~$1000 USD. Spend ~$200 USD > on a decent HBA. The 6G SAS/SATA LSI 9211-4i seems perfectly suited to > your RAID1 SSD application. It is a 4 port enterprise JBOD HBA that > also supports ASIC level RAID 1, 1E, 10. > > Also, the difference in throughput your show between RAID maintenance, > direct device access, and filesystem access suggests you have something > running between the block and filesystem layers, for instance LUKS. > Though LUKS alone shouldn't hammer your CPU and IO throughput so > dramatically. However, if the SSDs do compression or encryption > automatically, and I believe the 840s do, the LUKS encrypted blocks may > cause the SSD firmware to take considerably more time to process the blocks. > > -- > Stan > > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
