Berbagi Pengalaman Soal IT Bersama Honggi: December 2009

Sunday, December 13, 2009

Install Driver Printer HP LaserJet 1020 di Linux Fedora 11

Di kantor saya menggunakan printer HP Laser Jet 1020. Awalnya saya mengira driver printer ini sudah disupport (built-in) oleh Fedora 11 dengan menggunakan Gutenprint dan tipe printer: HP LaserJet 1010. Biasa kan, kalau linux tidak mengenali tipe terbaru, ya biasanya kita pakai tipe setingkat dibawahnya...

Ternyata ini tidak berhasil ! Perintah printing sudah dikirim namun printer diam saja, tidak menghasilkan apa-apa. Setelah bertanya kepada Windra (salah seorang staff ahli di bidang linux) ternyata untuk HP LaserJet 1020 bukan pakai Gutenprint, tapi foo2zjs. Wah, apalagi ini, langsung saya googling dan ketemu. Ternyata foo2zjs ini adalah driver external (third party) yang secara khusus memuat driver-driver printer HP LaserJet 1020.

Baik, langsung saya kerjakan langkah-langkah berikut ini :
1. Mendownload file drivernya dari Internet. Ambil disini -> http://foo2zjs.rkkda.com/foo2zjs.tar.gz
2. Extract file tersebut dengan menggunakan perintah : tar -zxvf foo2zjs.tar.gz
3. Saatnya kita compilasi source code ini ... dengan mengetikkan : make kemudian make install dan make install-hotplug
4. Restart CUPS dengan mengetikkan : make cups
5. Selesai deh ... tinggal di add lagi di CUPS Web Interfacenya...

Selamat mencoba !

Friday, December 11, 2009

About IDE, SATA, and SCSI Drives

IDE Drives

To save costs, many small business systems will probably use IDE disks, but they do have some limitations.

The total length of an IDE cable can be only a few feet long, which generally limits IDE drives to small home systems.
IDE drives do not hot swap. You cannot replace them while your system is running.
Only two devices can be attached per controller.
The performance of the IDE bus can be degraded by the presence of a second device on the cable.
The failure of one drive on an IDE bus often causes the malfunctioning of the second device. This can be fatal if you have two IDE drives of the same RAID set attached to the same cable.

For these reasons, I recommend you use only one IDE drive per controller when using RAID, especially in a corporate environment. In a home or SOHO setting, IDE-based software RAID may be adequate.

Serial ATA Drives

Serial ATA type drives are rapidly replacing IDE, or Ultra ATA, drives as the preferred entry level disk storage option because of a number of advantages:

The drive data cable can be as long as 1 meter in length versus IDE's 18 inches.
Serial ATA has better error checking than IDE.
There is only one drive per cable which makes hot swapping, or the capability to replace components while the system is still running, possible without the fear of affecting other devices on the data cable.
There are no jumpers to set on Serial ATA drives to make it a master or slave which makes them simpler to configure.
IDE drives have a 133Mbytes/s data rate whereas the Serial ATA specification starts at 150 Mbytes/sec with a goal of reaching 600 Mbytes/s over the expected ten year life of the specification.

If you can't afford more expensive and faster SCSI drives, Serial ATA would be the preferred device for software and hardware RAID

SCSI Drives

SCSI hard disks have a number of features that make them more attractive for RAID use than either IDE or Serial ATA drives.

SCSI controllers are more tolerant of disk failures. The failure of a single drive is less likely to disrupt the remaining drives on the bus.
SCSI cables can be up to 25 meters long, making them suitable for data center applications.
Much more than two devices may be connected to a SCSI cable bus. It can accommodate 7 (single-ended SCSI) or 15 (all other SCSI types) devices.
Some models of SCSI devices support "hot swapping" which allows you to replace them while the system is running.
SCSI currently supports data rates of up to 640 Mbytes/s making them highly desirable for installations where rapid data access is imperative.

SCSI drives tend to be more expensive than IDE drives, however, which may make them less attractive for home use.

Replacing A Failed Hard Drive In A Software RAID1 Array

This guide shows how to remove a failed hard drive from a Linux RAID1 array (software RAID), and how to add a new hard disk to the RAID1 array without losing data.

I do not issue any guarantee that this will work for you!

1 Preliminary Note

In this example I have two hard drives, /dev/sda and /dev/sdb, with the partitions /dev/sda1 and /dev/sda2 as well as /dev/sdb1 and /dev/sdb2.

/dev/sda1 and /dev/sdb1 make up the RAID1 array /dev/md0.

/dev/sda2 and /dev/sdb2 make up the RAID1 array /dev/md1.

/dev/sda1 + /dev/sdb1 = /dev/md0

/dev/sda2 + /dev/sdb2 = /dev/md1

/dev/sdb has failed, and we want to replace it.

2 How Do I Tell If A Hard Disk Has Failed?

If a disk has failed, you will probably find a lot of error messages in the log files, e.g. /var/log/messages or /var/log/syslog.

You can also run

cat /proc/mdstat

and instead of the string [UU] you will see [U_] if you have a degraded RAID1 array.

3 Removing The Failed Disk

To remove /dev/sdb, we will mark /dev/sdb1 and /dev/sdb2 as failed and remove them from their respective RAID arrays (/dev/md0 and /dev/md1).

First we mark /dev/sdb1 as failed:

mdadm --manage /dev/md0 --fail /dev/sdb1

The output of

cat /proc/mdstat

should look like this:

server1:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid5] [raid4] [raid6] [raid10]
md0 : active raid1 sda1[0] sdb1[2](F)
24418688 blocks [2/1] [U_]

md1 : active raid1 sda2[0] sdb2[1]
24418688 blocks [2/2] [UU]

unused devices:

Then we remove /dev/sdb1 from /dev/md0:

mdadm --manage /dev/md0 --remove /dev/sdb1

The output should be like this:

server1:~# mdadm --manage /dev/md0 --remove /dev/sdb1
mdadm: hot removed /dev/sdb1

And

cat /proc/mdstat

should show this:

server1:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid5] [raid4] [raid6] [raid10]
md0 : active raid1 sda1[0]
24418688 blocks [2/1] [U_]

md1 : active raid1 sda2[0] sdb2[1]
24418688 blocks [2/2] [UU]

unused devices:

Now we do the same steps again for /dev/sdb2 (which is part of /dev/md1):

mdadm --manage /dev/md1 --fail /dev/sdb2

cat /proc/mdstat

mdadm --manage /dev/md1 --remove /dev/sdb2

server1:~# mdadm --manage /dev/md1 --remove /dev/sdb2
mdadm: hot removed /dev/sdb2

cat /proc/mdstat

Then power down the system:

shutdown -h now

and replace the old /dev/sdb hard drive with a new one (it must have at least the same size as the old one - if it's only a few MB smaller than the old one then rebuilding the arrays will fail).

4 Adding The New Hard Disk

After you have changed the hard disk /dev/sdb, boot the system.

The first thing we must do now is to create the exact same partitioning as on /dev/sda. We can do this with one simple command:

sfdisk -d /dev/sda | sfdisk /dev/sdb

You can run

fdisk -l

to check if both hard drives have the same partitioning now.

Next we add /dev/sdb1 to /dev/md0 and /dev/sdb2 to /dev/md1:

mdadm --manage /dev/md0 --add /dev/sdb1

server1:~# mdadm --manage /dev/md0 --add /dev/sdb1
mdadm: re-added /dev/sdb1

mdadm --manage /dev/md1 --add /dev/sdb2

server1:~# mdadm --manage /dev/md1 --add /dev/sdb2
mdadm: re-added /dev/sdb2

Now both arays (/dev/md0 and /dev/md1) will be synchronized. Run

cat /proc/mdstat

to see when it's finished.

During the synchronization the output will look like this:

server1:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid5] [raid4] [raid6] [raid10]
md0 : active raid1 sda1[0] sdb1[1]
24418688 blocks [2/1] [U_]
[=>...................] recovery = 9.9% (2423168/24418688) finish=2.8min speed=127535K/sec

md1 : active raid1 sda2[0] sdb2[1]
24418688 blocks [2/1] [U_]
[=>...................] recovery = 6.4% (1572096/24418688) finish=1.9min speed=196512K/sec

unused devices:

When the synchronization is finished, the output will look like this:

server1:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid5] [raid4] [raid6] [raid10]
md0 : active raid1 sda1[0] sdb1[1]
24418688 blocks [2/2] [UU]

md1 : active raid1 sda2[0] sdb2[1]
24418688 blocks [2/2] [UU]

unused devices:

That's it, you have successfully replaced /dev/sdb!