Just did a blockwise test aswell with fio >
Single SSD :
# ./scst-trunk/scripts/blockdev-perftest -d -f -i 1 -j -m 10 -M 20 -s
30 -f /dev/sdb
blocksize W W(avg, W(std, W R R(avg,
R(std, R
(bytes) (s) MB/s) MB/s) (IOPS) (s) MB/s)
MB/s) (IOPS)
1048576 6.548 156.384 0.000 156.384 2.383 429.710
0.000 429.710
524288 6.311 162.256 0.000 324.513 2.521 406.188
0.000 812.376
262144 6.183 165.615 0.000 662.462 3.003 340.992
0.000 1363.969
131072 6.096 167.979 0.000 1343.832 3.140 326.115
0.000 2608.917
65536 5.973 171.438 0.000 2743.010 3.807 268.978
0.000 4303.651
32768 5.748 178.149 0.000 5700.765 4.609 222.174
0.000 7109.568
16384 5.693 179.870 0.000 11511.681 5.203 196.810
0.000 12595.810
8192 6.188 165.482 0.000 21181.642 7.339 139.529
0.000 17859.654
4096 10.190 100.491 0.000 25725.613 13.816 74.117
0.000 18973.943
2048 25.018 40.931 0.000 20956.431 26.136 39.180
0.000 20059.994
1024 39.693 25.798 0.000 26417.152 50.580 20.245
0.000 20731.040
RAID1 with two Intel330 SSDs:
# ./scst-trunk/scripts/blockdev-perftest -d -f -i 1 -j -m 10 -M 20 -s
30 -f /dev/md0
blocksize W W(avg, W(std, W R R(avg,
R(std, R
(bytes) (s) MB/s) MB/s) (IOPS) (s) MB/s)
MB/s) (IOPS)
1048576 7.053 145.186 0.000 145.186 2.384 429.530
0.000 429.530
524288 6.906 148.277 0.000 296.554 2.518 406.672
0.000 813.344
262144 6.763 151.412 0.000 605.648 2.871 356.670
0.000 1426.681
131072 6.558 156.145 0.000 1249.161 3.166 323.437
0.000 2587.492
65536 6.578 155.670 0.000 2490.727 3.835 267.014
0.000 4272.229
32768 6.311 162.256 0.000 5192.204 4.379 233.843
0.000 7482.987
16384 6.406 159.850 0.000 10230.409 5.953 172.014
0.000 11008.903
8192 7.776 131.687 0.000 16855.967 8.621 118.780
0.000 15203.805
4096 11.137 91.946 0.000 23538.116 14.138 72.429
0.000 18541.802
2048 38.440 26.639 0.000 13639.126 22.512 45.487
0.000 23289.268
1024 60.933 16.805 0.000 17208.672 43.247 23.678
0.000 24246.214
it sorta confirms that the performance goes down but I would kinda
expect that in a way aswell as the write confirm has to come from both
disks.
/Tommy
2013/4/21 Tommy Apel <tommyapeldk@xxxxxxxxx>:
> 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
>>
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