First number after S or U is bootloader number, in S7 Edge we have U4BQA6 witch red number indicate that bootloader is V4
U or S - Update Software or Security Update
4 - number after S or U Bootloader version
B - next version of Android. In example if last (6.1.1) was A next (7.0) will be B
Q - Year, A will be 01, Q- is 17
A - Month of creation of software , A-January, last one was K with was November we did not have L - December (edge users) because last security patch is from November.
Last number is version of software patch , can be multiple for same month release on different month
3 заходимо в папку
This post will show you how to enable or disable a service to start on boot, on a RHEL or CentOS 7.
You manage your services on RHEL/CentOS 7 through
systemctl, the systemd service manager.
In addition, keep in mind that MD (software raid) does not support discards. In contrast, the logical volume manager (LVM) and the device-mapper (DM) targets that LVM uses do support discards. The only DM targets that do not support discards are dm-snapshot, dm-crypt, and dm-raid45. Discard support for the dm-mirror was added in Red Hat Enterprise Linux 6.1.
Red Hat also warns that software RAID levels 1, 4, 5, and 6 are not recommended for use on SSDs. During the initialization stage of these RAID levels, some RAID management utilities (such as mdadm) write to all of the blocks on the storage device to ensure that checksums operate properly. This will cause the performance of the SSD to degrade quickly.
echo writemostly > /sys/block/md127/md/dev-sde1/state
You can enable "write-mostly" for a RAID component in the following way:
echo writemostly > /sys/block/md6/md/dev-sdc6/state and disable it this way:
echo -writemostly > /sys/block/md6/md/dev-sdc6/state If for some reason you cannot set a component of a RAID1 to "write-mostly", you can kick it from the array and re-add it with the write-mostly flag active. This will temporarily lower your redundancy level. Backup before doing this is recomended.
To set /dev/sdc6 from the last example to "write-mostly" would work as follows:
To kick, first set it to "faulty":
mdadm --fail /dev/md6 /dev/sdc6 Then kick it:mdadm --remove /dev/md6 /dev/sdc6 Then add it again:mdadm --add /dev/md6 --write-mostly /dev/sdc6 Wait for the RAID1 resync to complete, and /dev/sdc6 will now only be read when needed.
(updated Feb 29th 2016)
One problem that can comes up with the fantastic Centos Linux distro is that it sticks to the proven but also old packages. I needed some newer features several times. The only (good) way to upgrade Postfix to the newest package is to build it up from the source.
First, we need the link to the newest package (take a look here). In my case, it’s 2.11 stable, so let’s download it:
Now we need to isntall the development packages and the dependencies. These are the packages that I needed but You might need to install more, depending on which features You want to compile into it. For a standard featured Postfix MTA with SASL and MySQL support you’ll need the following:
Let’s celan up the makefiles now, and build new ones (because by the supplied makefile Postfix won’t be compiled with SASL and SQL support), and at the end let’s build the whole package:
The last step (build) will take a while, depeding on the CPU power of Your Linux box. At this moment, if it maneges to build without errors, you’ll have a ready to upgrade package. If not, you will need to yum groupinstall “Development Tools” and retry.
Regarding the arguments about building the makefile (step 3 above), depending on the features You want built in the new Postfix package please refer to the chapter 4.4 of the Postfix documentation. Basically, I never needed anything more than this, except that sometimes I want to use PgSQL instead of MySQL, then you will need to yum install postgresql-devel package and insert the correct arguments when creating the makefile.
creating the makefile in this example is done for Centos 6.x x64. If you are building for the 32-bit verion you will have to replace all the /usr/lib64 arguments with /usr/lib.
If everything is errorless, perform the update:
Done. Please also read the suggested articles during install about the new features, and sugested changes to the master.cf and main.cf files.
Regarding the package, since You done it by compiling from the source, the RPM package will stay at version 2.6.x but when you finally do a service postfix restart you will see:
Dec 3 09:23:56 one postfix/master: daemon started — version 3.0.3, configuration /etc/postfix
root@ismo:~# dmesg |grep command [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-2.6.32-25-generic root=UUID=b59249ce-9490-400d-a435-4c6669cb53ed ro splash
[root@sol-fttb ~]# hdparm -tT /dev/sdf
Timing cached reads: 17890 MB in 2.00 seconds = 8953.05 MB/sec
Timing buffered disk reads: 320 MB in 3.01 seconds = 106.40 MB/sec
You have new mail in /var/spool/mail/root
[root@sol-fttb ~]# hdparm -tT /dev/sdg
Timing cached reads: 17310 MB in 2.00 seconds = 8662.82 MB/sec
Timing buffered disk reads: 300 MB in 3.12 seconds = 96.25 MB/sec
hdparm -I /dev/sdf
NCQ (англ. Native Command Queuing — апаратна установка черговості команд) — технологія, що використовується в SATA-пристроях починаючи з SATA/300 для підвищення швидкодії. Пристрої з підтримкою NCQ здатні приймати декілька запитів одночасно та реорганізовувати порядок їх виконання для досягнення максимальної ефективності (продуктивності) з урахуванням внутрішньої архітектури пристрою (мінімізуючи кількість переміщень головок та очікування потрібного сектора на треку). NCQ підвищує продуктивність завдань, пов'язаних з довільним читанням, обробкою даних від двох і більше джерел, одночасну роботу декількох програм. (Типове навантаження для сервера — одночасне виконання запитів від декількох клієнтів).
You may disable NCQ, and use normal READ/WRITE DMA commands, by setting the queue depth to 1:...
A few years ago I worked as a Linux system administrator at a small (few hundred users) Internet service provider. Among all the regular system administrator duties, I also had the privilege to write various software and tools for Linux. One of my tasks was to write a tool to record how much traffic each of the clients was using.
The network for this provider was laid out in a very simple way. The gateway to the Internet was a single Linux box, which was a router, a firewall and performed traffic shaping. Now it had to be extended to do traffic accounting as well....
My Linux nas server connected to APC SmartUPS using usb cable and I would like to detect a power failure. If power is not restored my server must shutdown when the battery is exhausted. How do I configure and use my APC SmartUPS under Debina / Ubuntu / RHEL / CentOS / Fedora / Scientific Linux operating system for power management?
Linux comes with GPL licensed open source apcupsd server ( daemon ) that can be used for power mangement and controlling most of APC's UPS models on Linux, BSD, Unix and MS-Windows operating systems. Apcupsd works with most of APC's Smart-UPS models as well as most simple signalling models such a Back-UPS, and BackUPS-Office. During a power failure, apcupsd will inform the users about the power failure and that a shutdown may occur. If power is not restored, a system shutdown will follow when the battery is exhausted, a timeout (seconds) expires, or runtime expires based on internal APC calculations determined by power consumption rates.
можна подивитися на приклад чату https://github.com/socketio/socket.io/tree/master/examples/chat
але щоб недуже загубитися в двох сторінках коду є простий приклад який на ссервері пише в консоль а на браузері в консоль браузера