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Remote SAP Basis & VMware Support


Gue barusan memproklamirkan diri (ha…ha..ha.. pake proklamasi segala)untuk menjadi Freelance Remote SAP Basis. Artinya company-company termasuk yang di Indonesia dan pakai SAP bisa hire gue untuk melakukan tugas-tugas sebagai SAP Basis secara remote.

Saat ini gue menambahkan vmware kedalam daftar aplikasi yang gue support.

Rate salary negotiable. Untuk lebih detailnya, silakan klik disini.

Atau bisa kontak langsung saya.

YM ID : Ardhian

Email : devratt@yahoo.com

SAP XI Installation Part#2


Setelah melakukan step prerequisites check (opsional), silakan lanjutkan ke proses instalasi.

Masuk ke direktori installation master dan set beberapa environment setting, antara lain SAPINST_JRE_HOME, JAVA_HOME, LD_LIBRARY_PATH (karena gw pake Linux), dan umask.

Selanjutnya jalankan file sapinst dan pilih Standard System.

Pilih Custom. (more…)

SAP XI Installation part#1


Berangkat dari iseng aja, kemaren gw mencoba untuk melakukan instalasi SAP XI. Setelah melihat beberapa video dan dokumentasi dari beberapa forum, akhirnya gw download beberapa software yang diperlukan untuk melakukan instalasi SAP XI (SAP Exchange Infrastructure). Yang gw download dan install ini masih versi yang agak lama tapi overall versi baru masih sama.

Beberapa software yang perlu disiapkan (dapat didownload dari SAP Marketplace portal) adalah

  • SAP XI Kernel
  • RDBMS dan client (dalam hal ini saya pake DB2, bisa pake RDBMS lain)
  • Bahasa (Language)
  • SAP XI Installation Master
  • SAP Export untuk ABAP Stack
  • SAP Export untuk Java Stack (jika memakai dual stack)
  • SAP DB2 License (tidak perlu jika memakai DB lain, misal Oracle)

Sekarang step untuk memeriksa prerequisite. (more…)

ZRAM vs ZSWAP vs ZCACHE


Another interesting to “oprex” :

Summary of what to use when:

  1. ZRAM if you have no HDD/SSD swap partition.
  2. ZSWAP if you do have a HDD/SSD swap partition.
  3. ZCACHE: It does what ZSWAP does and ALSO compresses and speeds the filesystem page cache. (It is internally much more complicated and is not in the mainline kernel as it is still under development).

Summary of their implementations:

  1. ZRAM is a compressed RAM based swap device
  2. ZSWAP is a compressed Cache if you already have a swap.
  3. ZCache is a backend for a special type of Virtual RAM thingy (Transcendent memory) that can be used to cache filesystem pages or swap data.

Details:

  • ZRAM: Makes a swap device in the RAM. Pages sent here are compressed as they are stored. It has a higher priority than other swap devices: pages that are swapped out are preferentially sent to the zram device till it is full, only then are any other swap devices used.
    • Benefits: Independent of other (physical) swap devices. It can be used when there is no swap partition to expand the available memory.
    • Disadvantages: If other swap devices (HDD/SSD) are present they are not used optimally. As the zram device is an independent swap device, once it is full, any new pages that need to be swapped out are sent to next swap device directly, hence:
      1. There is a real chance of LRU (least recently used) inversion: It will be the most recently swapped data that goes to the slow disk, while inactive pages that were swapped out long ago will remain in the fast ZRAM
      2. The data sent to and read from the disk will consume a lot of bandwidth as it is uncompressed.
        • Status: Merged into the mainline kernel 3.14. Once enabled on a system, it requires some userspace configuration to set up the swap devices and use them.
  • ZSWAP: The frontswap system hooks attempts to swap out pages and uses zswap as write-back-cache for a HDD/SSD swap device: An attempt is made to compress the page and if it contains poorly compressible data it is directly written two the disk. If the data is compressed, it is stored in the pool of zswap memory. If pages are swapped out of memory when the total compressed pages in RAM exceeds a certain size, the Least Recently Used (LRU) compressed page is written to the disk as it is unlikely to be required soon.
    • Benefits: Very efficient use RAM and disk based swap. Minimizes Disk I/O by both reducing the number of writes and reads required (data is compressed and held in RAM) and by reducing the bandwidth of these I/O operaions as the data is in a compressed form.
    • Limitations: It is an enhancement of disk based swap systems and hence depends on a swap partition on the hard disk.
    • Status: Merged into the 3.11 mainline linux kernel.
  • ZCache: It is a backend for the Transcendent memory system. Transcendent memory provides a RAM-like memory that can only be accessed a page at a time by using put and get calls. This is unlike normal memory that can be accessed a byte at a time. The frontswap and cleancache systems hook attempts to swap and reclaim file-system page caches respectively and send them to the transcendent memory backends. When zcache is used as a backend, the data is compressed and stored in the RAM. When it fills up, compressed pages are evicted to the swap. (an alternate backend is RAMster which shares a pool of RAM across networked computers). Using only the frontswap frontend with the zcache backend works just like zswap. (In fact zswap is a simplified subset of zcache)
    • Benefits Provides compressed caching both for swap and for filesystem caches.
    • Status: Still not mainlined as it is very complicated and is being worked on.

The best resources I found were:

Step by step instalasi DB2 10.5 FP4 di SLES 11 SP 3


Versi terbaru DB2 10.5 yang disupport oleh SAP saat ini adalah DB2 10.5 FP 4. Berikut step by step instalasi disertai screenshot.

Sebelum melakukan instalasi, siapkan dulu OS-nya (dalam hal ini saya pake SuSE Linux Enterprise Server 11 SP 3). Untuk lebih memperlancar proses instalasi, maka saya lakukan prerequisite check terlebih dahulu.

Hasil prereqcheck :

Start instalasi dengan db2setup. (more…)

Tuning Browser Performance dengan Profile-Sync-Daemon


Setelah melakukan tuning di sisi direktori sementara (temporary directory, /tmp, sekarang gw mencoba melakukan tuning sekali lagi pada sisi akses profile browser. Gw pake beberapa browser (Firefox, Google-Chrome, dan Opera), namun gw hanya akan melakukan tuning di Firefox aja. Sebenarnya bisa semua profile browser, tapi hanya akan membebani RAM karena gw sekali lagi akan memanfaatkan tmpfs yang seperti diketahui sangat bergantung pada RAM.

Ada script kecil yaitu profile-sync-daemon yang dapat melakukan itu semua. Cukup mudah instalasinya di Ubuntu dan turunannya.

sudo add-apt-repository ppa:graysky/utils
sudo apt-get update
sudo apt-get install profile-sync-daemon

(more…)

Setting Up a NFS Server on Top of tmpfs /dev/shm


tmpfs has blazing speed. Why not set up a high speed NFS server on top of tmpfs?

A little trick is required for setting NFS server on top of /dev/shm. If we add a normal entry in /etc/export and them run

# exportfs -a

exportfs will give us a warning like this: exportfs: Warning: /dev/shm requires fsid= for NFS export

When we try to mount this NFS server, we may get a error message from mount: mount.nfs: access denied by server while mounting nfsserver:/dev/shm

How to solve this problem? Just add the option fsid=1 to the /dev/shm entry in /etc/exports:

/dev/shm 10.0.0.1/24(rw,fsid=1,sync)

and remember to execute # exportfs -a again.

Then nfsserver:/dev/shm can be mounted in 10.0.0.1/24.

Linux Tuning : Memanfaatkan tmpfs


Setelah gw menggunakan fitur zram dalam host linux di notebook yang gw gunakan untuk bekerja sehari-hari dan menggunakan btrfs sebagai file system untuk data, kali ini gw mencoba untuk melakukan tuning performance sekali lagi. Kali ini gw memanfaatkan file system virtual, tmpfs yang secara default sudah disupport oleh kernel Linux.

Sebagaimana  kita tahu bahwa pada beberapa direktori seperti /tmp dan /var/tmp/ adalah direktori temporari yang digunakan oleh sistem Linux untuk menyimpan file dan direktori secara temporary. Pada saat Linux akan di-shutdown, maka direktori temporari tersebut akan di-clear dan dihapus termasuk isi-nya. Nah, berangkat dari pengertian itu, maka akan lebih baik jika direktori dan isi-nya tersebut ditempatkan di RAM. Akses RAM lebih cepat daripada akses ke disk.

Disclaimer : Gw hanya menyarankan untuk digunakan di notebook ataupun desktop. Tidak disarankan digunakan di server karena tuning kali ini belum menyertakan skrip untuk mem-flush / menuliskan isi direktori tersebut ke disk.

(more…)

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