adm blog

ffmpeg -i ./some.mp4 -vcodec hevc_nvenc -b:v 5000k -r 30 ./nvenc.mp4

dism /online /cleanup-image /startcomponentcleanup /resetbase

вырезаем из всего выхлопа только фуллчейн и ключ. нормализуем.

cat ./response.json |jq .data[].fullchain |tr -d \" |sed -s 's/\\r\\n/\n/g' |sed 's/\\r\\n/\n/g' |sed 's/\\n-----BEGIN CERTIFICATE-----/-----BEGIN CERTIFICATE-----/' > ./cert.chain
cat ./response.json |jq '.data[].privateKeyEncrypted.key' |tr -d \" |base64 -d > ./enc.private.pem

распароливаем

openssl rsa -in ./enc.private.pem  -out ./private.pem
Enter pass phrase for ./enc.private.pem:
writing RSA key

или однострочником

cat ./response.json |jq .data[].root |tr -d \" |sed 's/\\r\\n/\n/g' > ./cert.chain && cat ./response.json |jq .data[].fullchain |tr -d \" |sed 's/\\r\\n/\n/g' |sed 's/\\n-----BEGIN CERTIFICATE-----/-----BEGIN CERTIFICATE-----/' >> ./cert.chain && cat ./response.json |jq '.data[].privateKeyEncrypted.key' |tr -d \" |base64 -d > ./enc.private.pem && openssl rsa -in ./enc.private.pem  -out ./private.pem && cat ./private.pem >> ./cert.chain

ls -l /sys/block/sd* | sed 's/.*\(sd.*\) -.*\(ata.*\)\/h.*/\2 => \1/'

fastest way to test streams:

ffmpeg -i rtsp://<user>:<pass>@<ipaddress>:554/path ./output.mp4 (if terminal only)
ffplay rtsp://<user>:<pass>@<ipaddress>:554/path (gui)

find paths on ispydb or in zm hcl

If you are new to security software, read:
https://wiki.zoneminder.com/Dummies_Guide

docker pull grafana/grafana
docker stop grafana
docker rm grafana
docker run -d --name=grafana -p 3000:3000 --restart=always -v /var/lib/grafana:/var/lib/grafana grafana/grafana

meshtastic docker run

docker run -d -p 8081:8080 --restart always --name Meshtastic-Web ghcr.io/meshtastic/web

board info

ipmitool -I lanplus -H IPSRV -U admin -P PASSWORD fru

ipmi reset

ipmitool -I lanplus -H IPSRV -U admin -P PASSWORD mc reset cold

file.mib to file.txt

for i in *.mib; do mv $i `basename $i mib`txt; done

список хостов:

cat ./list
host1
host2

команда

for i in `cat ./list`; do host $i |cut -d ' ' -f 4; done

https://wiki.openjdk.java.net/display/shenandoah/Main

Basic configuration

Basic configuration and command line options:

-Xlog:gc (since JDK 9) or -verbose:gc (up to JDK 8) would print the individual GC timings.

-Xlog:gc+ergo (since JDK 9) or -XX:+PrintGCDetails (up to JDK 8) or would print the heuristics decisions, which might shed light on outliers, if any.

-Xlog:gc+stats (since JDK 9) or -verbose:gc (up to JDK 8) would print the summary table on Shenandoah internal timings at the end of the run.

It is almost always a good idea to run with logging enabled. This summary table conveys important information about GC performance, and we would almost inevitably ask for one in a performance bug report. Heuristics logs are useful to figure out GC outliers.

Other recommended JVM options are:

-XX:+AlwaysPreTouch: committing heap pages into memory helps to reduce latency hiccups

-Xms and -Xmx: making the heap non-resizeable with -Xms = -Xmx reduces hiccups with heap management. Coupled with AlwaysPreTouch, the -Xms = -Xmx would commit all memory on startup, which avoids hiccups when memory is finally used. -Xms also defines the low boundary for memory uncommit, so with -Xms = -Xmx all memory would stay committed. That said, if you want to configure Shenandoah for lower footprint, then setting lower -Xms is recommended. You need to decide how low to set it to balance the commit/uncommit overhead vs memory footprint. In many cases, setting -Xms arbitrarily low would be fine.

Using large pages greatly improves performance on large heaps. There are two ways to opt-in. -XX:+UseLargePages would enable hugetlbfs (Linux) or Windows (with appropriate privileges) support. -XX:+UseTransparentHugePages would enable it transparently. With transparent huge pages, it is recommended to set /sys/kernel/mm/transparent_hugepage/enabled and /sys/kernel/mm/transparent_hugepage/defrag to «madvise». When running with AlwaysPreTouch, it will also pay the defrag costs upfront at startup.

-XX:+UseNUMA: while Shenandoah does not support NUMA explicitly yet, it is a good idea to enable this to enable NUMA interleaving on multi-socket hosts. Coupled with AlwaysPreTouch, it provides better performance than the default out-of-the-box configuration

-XX:-UseBiasedLocking: there is a tradeoff between uncontended (biased) locking throughput, and the safepoints JVM does to enable and disable them as needed. For latency-oriented workloads, it makes sense to turn biased locking off.

-XX:+DisableExplicitGC: invoking System.gc() from user code forces Shenandoah to perform additional GC cycle; it might be profitable to disable this to protect from the code that abuses System.gc(). It usually does not hurt, as -XX:+ExplicitGCInvokesConcurrent gets enabled by default, which means the concurrent GC cycle would be invoked, not the STW Full GC.

Heuristics

transport.type: netty3
http.type: netty3


# Recover only after the given number of nodes have joined the cluster. Can be seen as "minimum number of nodes to attempt recovery at all".
gateway.recover_after_nodes: 8
# Time to wait for additional nodes after recover_after_nodes is met.
gateway.recover_after_time: 5m
# Inform ElasticSearch how many nodes form a full cluster. If this number is met, start up immediately.
gateway.expected_nodes: 10


yum install java-latest-openjdk

vim /etc/sysconfig/elasticsearch
JAVA_HOME=/usr/lib/jvm/java-13-openjdk-13.0.1.9-2.rolling.el7.x86_64

vim /etc/elasticsearch/jvm.options

#13 java
-XX:+UnlockExperimentalVMOptions
-XX:+UseShenandoahGC

#-XX:+UseConcMarkSweepGC
#-XX:CMSInitiatingOccupancyFraction=75
#-XX:+UseCMSInitiatingOccupancyOnly

https://click.ru/jiufs

-XX:MaxDirectMemorySize=16g
-Djdk.nio.maxCachedBufferSize=262144

mmapfs -> niofs -> hybridfs

jdk13
-XX:+UnlockExperimentalVMOoptons
-XX:+ShenandoahGC

thread_pool.write.queue_size 200 -> 300
http.max_content_length = 500mb

es6 — use_adaptive_replica_selection: true

curl -s -XPOST -H "Content-Type: application/json" 'http://localhost:9200/_license/start_basic?acknowledge=true'

add snipet section

<Extension charconv>
    Module xm_charconv
    AutodetectCharsets windows-1251, utf-8
</Extension>

and add to any log inputs — verbatim configuration

Exec                convert_fields("auto", "utf-8");

reboot
echo 1 > /proc/sys/kernel/sysrq 
echo b > /proc/sysrq-trigger

halt
echo 1 > /proc/sys/kernel/sysrq 
echo o > /proc/sysrq-trigger

keep SysRq enabled all the time
kernel.sysrq = 1

apt install letsencrypt

stop nginx/apache

certbot certonly --standalone -d mydomain.tld

прогнать диски

создаем в _текущем_ каталоге файлы для тестов. 10 штук. суммарным размером 100 гигов. про блок — не уверен, требует проверки.

sysbench --file-total-size=100G --file-block-size=4K --file-num=10 fileio prepare

и пускаем 32 потока, fsync после каждого записанного блока. тест случайных записи и чтения. в подготовленные 10 файлов, общим размером в 100Гигов. длинна теста секундах, у нас — 2 часа.

sysbench --file-total-size=100G --file-test-mode=rndrw --time=7200 --file-block-size=4K --file-num=10 --threads=32 --file-fsync-all=on fileio run

прогнать процессор в 72 потока, на 2 часа.

sysbench --time=7200 --threads=72 cpu run

parted -s -a optimal /dev/nvme2n1 mklabel GPT print mkpart primary xfs 0% 100% name 1 'nvme03' print