How to measure IOPS with linux
So many times I need to measure the amount of IOPS on a Linux disk/storage system. While there are many tools for the jobs they just don’t seem to give you a ‘number’. For example Splunk indexers require 1200+ IOPS according to hardware recommendation guides but how do you find out if your any where close to that number? Use ‘bonnie++’, ‘iozone’ or perhaps ‘fio’? Well use any of those tools will create the type of read / write sequence you would like to replicate - but where the damn magic number???
Easiest two ways are:
Method #1:
run iozone -a (or bonnie++) in one screen then in another session / terminal use nmon, pressing D (capital D) to get disk stats and get the number from the Xfers column. This is your magic number (or IOPS reading)
┌nmon─14i─────────────────────Hostname=reddragon─────Refresh= 2secs ───19:51.57─ │ Disk I/O ──/proc/diskstats────mostly in KB/s─────Warning:contains duplicates─ │DiskName Busy Read Write Xfers Size Peak% Peak-RW InFlight │sda 99% 699.9 14.0KB/s 178.0 4.0KB 493% 3658.8KB/s 1 │sda1 0% 0.0 0.0KB/s 0.0 0.0KB 0% 0.0KB/s 0 │sda2 99% 699.9 14.0KB/s 178.0 4.0KB 493% 3658.8KB/s 1 │dm-0 0% 0.0 0.0KB/s 0.0 0.0KB 0% 0.0KB/s 0 │dm-1 99% 699.9 14.0KB/s 178.5 4.0KB 494% 3658.8KB/s 1 │dm-2 0% 0.0 0.0KB/s 0.0 0.0KB 76% 2553.5KB/s 0 │Totals Read-MB/s=2.1 Writes-MB/s=0.0 Transfers/sec=534.4
In the above example I’m getting about 178 IOPS for my disk ’sda’
Method #2:
run fio with the correct workload (google how to use fio) and while it’s running it will actually tell you the IOPS.
[root@reddragon ~]# fio random-read-test.fio random-read: (g=0): rw=randread, bs=4K-4K/4K-4K/4K-4K, ioengine=sync, iodepth=1 fio-2.0.13 Starting 1 process Jobs: 1 (f=1): [r] [85.1% done] [736K/0K/0K /s] [184 /0 /0 iops] [eta 00m:28s]
In this example I am getting 184 IOPS. Also if you wait until fio finishes it run - you can the IOPS reading from there. Eg.
random-read: (g=0): rw=randread, bs=4K-4K/4K-4K/4K-4K, ioengine=sync, iodepth=1 fio-2.0.13 Starting 1 process Jobs: 1 (f=1): [r] [98.9% done] [2224K/0K/0K /s] [556 /0 /0 iops] [eta 00m:02s] random-read: (groupid=0, jobs=1): err= 0: pid=7239: Tue Feb 25 16:49:16 2014 read : io=131072KB, bw=747406 B/s, iops=182 , runt=179578msec clat (usec): min=107 , max=117530 , avg=5473.62, stdev=4112.08 lat (usec): min=107 , max=117531 , avg=5473.93, stdev=4112.08 clat percentiles (usec): | 1.00th=[ 245], 5.00th=[ 302], 10.00th=[ 370], 20.00th=[ 2480], <SNIP>
As you can see: iops=182 - pretty consistent with the other results!
Squid ICAP Syntax with F-Secure Internet Gate Keeper (IGK)
*** UPDATE September 2015 - This article has been updated with the correct syntax and confirmed working on Squid 3.3.8 ***
The doco for IGK is some what lacking for the ICAP settings but it does mention ” Refer to the documentation of the proxy for information on how to set it up”. That’s not very helpful so I contacted F-Secure technical support and asked them. This is the reply:
You will need to add these lines to Squid config file:
icap_enable on icap_send_client_ip on icap_service service_req reqmod_precache bypass=1 icap://[IP address of IGK]:1344/request adaptation_access service_req allow all icap_service service_resp respmod_precache bypass=0 icap://[IP address of IGK]:1344/response adaptation_access service_resp allow all
Unfortunately that still doesn’t work for some unknown reason and I am only getting the error:
ErrPage: ERR_CANNOT_FORWARD
I don’t have anymore time to spend on this, I guess I’ll just use the F-Secure HTTP proxy as a parent proxy for squid.
Stop puppet spamming /var/log/messages
Hate Spam? Hate Puppet Spam in var/log/messages more? Quick buy now!
# Edit /etc/puppet/puppet.conf # In the [agent] section add: syslogfacility = local6 # Edit: vi /etc/rsyslog.conf # Do a quick to see if local6 is being used somewhere else first... # Add a line: local6.* /var/log/puppet/puppet.log # Add setup the permissions and file touch /var/log/puppet/puppet.log chown puppet:puppet /var/log/puppet/puppet.log chmod 640 /var/log/puppet/puppet.log service rsyslog reload
And your done!
Cleanup whitespace on partitions before compression
Just a quick tip to help reduce the size of compressed partitions; particularly useful if imaging a drive for cloning etc. This tip comes from Bowen and Vagrant
apt-get clean -y
apt-get autoclean -y
# Zero free space to aid VM compression
dd if=/dev/zero of=/EMPTY bs=1M
rm -f /EMPTY
# Remove bash history
unset HISTFILE
rm -f /root/.bash_history
# Cleanup log files
find /var/log -type f | while read f; do echo -ne '' > $f; done;
# Whiteout root
count=`df --sync -kP / | tail -n1 | awk -F ' ' '{print $4}'`;
let count--
dd if=/dev/zero of=/tmp/whitespace bs=1024 count=$count;
rm /tmp/whitespace;
# Whiteout /boot
count=`df --sync -kP /boot | tail -n1 | awk -F ' ' '{print $4}'`;
let count--
dd if=/dev/zero of=/boot/whitespace bs=1024 count=$count;
rm /boot/whitespace;
# Whiteout swap
swappart=`cat /proc/swaps | tail -n1 | awk -F ' ' '{print $1}'`
swapoff $swappart;
dd if=/dev/zero of=$swappart;
mkswap $swappart;
swapon $swappart;
Amavisd default action isn’t to discard spam
When you install amavisd-new it appears the spam still gets passed on to the sender.
The default action in /etc/amavisd.conf around line 163 is:
# final_spam_destiny => D_BOUNCE;
One would presume based on prior experience with config files that, while it is commented out, that would be the default action. From what I have seen it isn’t. What seems to actually happens is that if ‘$*_quarantine_to’ variable is assigned emails will get delivered there and to the original recipient. Suggesting the D_PASS is the default.
Anyway to fix it, just uncomment and change
# final_spam_destiny => D_BOUNCE;
to:
final_spam_destiny => D_DISCARD;
and restart amavisd service.
Further information:
D_PASS Mail will pass to recipients, regardless of bad contents. If a quarantine is configured, a copy of the mail will go there, if not, at least the recipient received the mail. Note that including a recipient in a @*_lovers_maps is functionally equivalent to setting $final_*_destiny = D_PASS; for that recipient.
D_BOUNCE Mail will not be delivered to its recipients. A non-delivery notification (bounce) will be created by amavisd-new and sent to the sender by amavisd-new. Exceptions: bounce (DSN) will not be sent if a virus name matches @viruses_that_fake_sender_maps , or to messages from mailing lists (Precedence: bulk|list|junk), or for spam level that exceeds the $sa_dsn_cutoff_level. If a quarantine is configured, a copy of the mail will go there. If not, we have lost the mail, but if the mail was legitimate, the sender should receive notification of the disposition of the message.
D_DISCARD Mail will not be delivered to its recipients and the sender normally will NOT be notified. If a quarantine is configured, a copy of the mail will go there. If not, we have lost the mail. Note that there are additional settings available that can send notifications to persons that normally may not be notified when an undesirable message is found, so it is possible to notify the sender even when using D_DISCARD.