Linux disk test with dd

Laptop Example
In this example, the test data will be written to /dev/sda2. The test system (a Thinkpad T43 Type 2668-4GG) had 1.5 GByte of RAM and a Fujitsu MHT2060AH hard disk rotating at 5,400 rpm.

Laptop Throughput (Streaming I/O)
One gigabyte was written for the test, first with the cache activated (hdparm -W1 /dev/sda):

root@grml ~ # dd if=/dev/zero of=/dev/sda2 bs=1G count=1 oflag=direct
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 32.474 s, 33.1 MB/s
root@grml ~ #
Then, with the cache deactivated (hdparm -W0 /dev/sda):

root@grml ~ # dd if=/dev/zero of=/dev/sda2 bs=1G count=1 oflag=direct  
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 123.37 s, 8.7 MB/s
root@grml ~ #
Laptop Latency
In this test, 512 bytes were written one thousand times, first with the cache activated (hdparm -W1 /dev/sda):

root@grml ~ # dd if=/dev/zero of=/dev/sda2 bs=512 count=1000 oflag=direct
1000+0 records in
1000+0 records out
512000 bytes (512 kB) copied, 0.36084 s, 1.4 MB/s
root@grml ~ #
Then, with the cache deactivated (hdparm -W0 /dev/sda): One thousand accesses required 11.18 seconds, meaning one access took 11.18 ms.

root@grml ~ # dd if=/dev/zero of=/dev/sda2 bs=512 count=1000 oflag=direct
1000+0 records in
1000+0 records out
512000 bytes (512 kB) copied, 11.1865 s, 45.8 kB/s
root@grml ~ #
Server with RAID10 Example
In this example, the test data was written to an empty partition. The test system was an 2HE Intel Dual-CPU SC823 Server with six 147 GB SAS Fujitsu MBA3147RC (15,000 rpm) hard disks and an Adaptec 5805 RAID controller with the cache activated and a BBU.

Server Throughput (Streaming I/O)
One gigabyte was written for the test:

test-sles10sp2:~ # dd if=/dev/zero of=/dev/sda6 bs=1G count=1 oflag=dsync
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 5.11273 seconds, 210 MB/s
test-sles10sp2:~
Server Latency
In this test, 512 bytes were written one thousand times. Thereby, the 0.084 seconds that were measured for one thousand accesses corresponded to precisely 0.084 ms for each access. This value is so low because of the RAID controller’s cache:

test-sles10sp2:~ # dd if=/dev/zero of=/dev/sda6 bs=512 count=1000 oflag=dsync
1000+0 records in
1000+0 records out
512000 bytes (512 kB) copied, 0.083902 seconds, 6.1 MB/s
test-sles10sp2:~ #
source

Freebsd ping: sendto: No buffer space available

Put in your loader.conf

kern.ipc.nmbclusters=524288
hw.igb.rxd=4096
hw.igb.txd=4096
hw.em.rxd=4096
hw.em.txd=4096

net.inet.tcp.recvbuf_max=20097152
net.inet.tcp.sendbuf_max=20097152