Usb2 vs usb3 under linux

Lately I've been buying laptop for myself. And was wandering if I need one with usb3 ports. I've already got usb3 mobile 2'5 hdd, but I've thought that 5400rpm hdd doesn't really need usb3. Finally I've got laptop with usb3 so I have to run some tests ;).
Used bonnie++ on hdd connected to usb3 port and usb2 port. Here are results:



In quest of perfect laptop

Lately (for like 3 years), I've been looking for perfect laptop. I've been using 10+ of them during that period owned two, having three company ones. One of company laptops was almost perfect.
What is perfect laptop for me? Having those features:
* cpu with virtualization (to let me use windows VMs),
* cpu with AES (to let me use my luks crypted disks without loosing too much performance),
* gpu with vdpau support, which means nvidia card (with at least pure video feature set C),
* fast 300GB+ hdd – 7200 rpm, hybrid or ssd,

Useful shell/kernel commands

Some useful commands you can issue from shell, to change some kernel/system parameters. Guess there gonna be more later, but now some I use very often.

echo "scheduler_name" > /sys/block/"device_name"/queue/scheduler
changes ioscheduler for block device "device_name" (e.g. sda, xvda, hda), to "scheduler_name", where "scheduler_name" could be: noop, anticipatory, deadline or cfq.

To rescan SCSI device use:
echo "1" > /sys/bus/scsi/drivers/sd/"device_address"/rescan where "device_address" is something like 0:2:0:0.

Bonnie++ results database

Finally I've just found small amount of time to write 2 PHP scripts and create database with all bonnie++ results I've got. All tests were run by me. Some tests do not have character speeds (those got -1 value there). You can sort results by: block write speed, character write speed, rewrite, block read speed, character read speed and seeks. You can also narrow results down by filtering LVM, encryption and filesystem type. Every new bonnie++ runs gonna go there.

Hope some of you gonna find this useful. Link is

vSphere 5 hardware dependant iSCSI vs software iSCSI on Broadcom NetXtreme II 5709c

Recently I've been setting up vSphere 5 infrastructure with 2 iSCSI storages.

LUKS and intel AES extension performance

Finally I've just got cpu with AES-NI to play with. And finally I was able to check performance gain using hadrware with LUKS volumes.
Edit: most important info, tested CPU was Intel Xeon X5650.

First of all I've checked block device speed (which was 2 SAS 300GB RAID1 set) without encryption. Device has ext4 and I used bonnie++ as usual.


Setting RAID alerts with amCLI

All modern raid controllers comes with nice graphics interfaces, but this tools needs time to setup and resources to run (most of them are java based). But all LSI controllers (almost in every modern IBM x series or Fujitsu TX, RX series) got nice console tool to manage them (amCLI). It's even easier to set up mail alerts with this tool than with GUI, but manual for amCLI is rather lame.

LVM based backup of virtual machines

LVM is one of the greatest things in linux. So much powerful, elastic and smooth approach to block devices.
You can use it almost everywhere.

How to crack LM Hash online

LMHash is algorithm to encrypt password in some MS windows versions. Almost every administrator knows that LMhash is not safe way to keep paswords, but some ppl still use it especially for backwards compatibility. I would call it stupidity, but you can call it however you want.
There are tons of tools over the internet to extract those hashes from windows machines, from ldap databases and so on.

iotop and Centos 5.6

Kernel 2.6.20+ got real-time process IO statistics accounting. Nice tool to monitor this is iotop, but even thought it's available in rpm, it's not working well on Centos.
If you want install iotop on Centos just install it from EPEL repository. Kernel got already all needed options turned on.
So just add EPEL repo to your system and then
yum install iotop

Another nice tool to monitor system I/O is dstat especially with options --top-bio-adv and --top-io-adv.



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by Dr. Radut