Converting compressed .Z files to compressed .gz files

I had a situation today that required me to convert a compressed file from a .Z ( adaptive Lempel-Ziv coding ) to a .gz (Lempel-Ziv coding) file to save space. While reading through the gzip documentation, I stumbled across the znew(1) command. This command allows you to switch between file compression types with a single command:

$ znew -K -P -v -9 file.Z
77.2%

One this completed, I had the following files in my home directory:

-rw-r--r--  1 matty matty 272826735 May  6 15:46 file.Z
-rw-r--r--  1 matty matty 200377928 May  6 15:46 file.gz

This example uses several options. The “-P” option instructs znew to use pipes to transfer data between code segments, the “-K” options forces znew to keep .Z files if they are smaller than the original gzip’ed file, and the “-v” option displays verbose output. The difference in compressed file sizes leads me to wonder what “adaptive” is adapting to! :)

Base conversions with bc

Whiile reading through Planet Sun I stumbled across Chris Gerhard’s base conversion post. I replied with an alternate solution using bc(1), which I have used extensively through the years. bc(1) is a command line calculator that can convert between bases when the “ibase” and “obase” options are used. The following example shows how to convert a base 10 number to it’s hexidecimal equivalent:

$ bc
obase=16
12345677
BC614D

We can also use bc to convert a hexidecimal value to decimal:

$ bc
ibase=16
FF
255

This gets even better! We can convert a hexidecimal value to binary:

$ bc
ibase=16
obase=2
FF
11111111

I really really like bc (and dc)!

Replacing failed disk devices with the Solaris Volume Manager

While reviewing a post I left on blogs.sun.com, I noticed that Jerry Jelinek replied to my post on replacing disks managed by the Solaris Volume Manager. I had run into the exact issue he covered in his BLOG, and was glad to see that the disk replacement annoyance was addressed in the latest Solaris Express.

The following example (per Jerrry’s feedback and limited testing in my sandbox) will show how to replace a disk named c0t0d0 using the cfgadm(1m) and metareplace(1m) utilities. The first step is to remove (if they exist) any meta state databases on the disk that needs to be replaced. To locate the locations of all meta state databases, the metadb(1m) command can be run with the “-i” option:

$ metadb -i

If meta devices exist, you can run metadb(1m) with the “-d” option to remove the databases. The following example deletes all meta state databases on slice 7 of the disk (c0t0d0) that we are going to replace:

$ metdb -d c0t0d0s7

Once the meta state databases are removed, you can use cfgadm(1m)’s “-c unconfigure” option to remove an occupant (an entity that lives in a receptacle) from Solaris:

$ cfgadm -c unconfigure c0::dsk/c0t0d0

Once Solaris unconfigures the device, you can physically replace the disk. Once the drive is replaced, you can run cfgadm(1m) with the “-c configure” option to let Solaris know the occupant is available for use:

$ cfgadm -c configure c0::dsk/c0t0d0

Once Solaris know the drive is available, you will need to VTOC the new drive with fmthard(1m) or format(1m). This will add a disk label to the drive, which defines the partions types and sizes. Once a valid VTOC is installed, you can invoke the trusty old metareplace(1m) utility to replace the faulted meta devices. The following example will replace the device associated with meta device d10, and cause the meta device to start synchronizing data from the other half of the mirror ( if RAID level 1 is used):

$ metareplace -e d10 c0t0d0s0

I dig the terminology cfgadm(1m) uses to describe the connections between components. “Receptable,” “occupant” and “atachment point” should be used a bit more universally in the IT industry! :) I recommend testing all examples in a sandbox prior to use in production (i.e., I am not responsible for breaking your stuff)!

Monitoring LDAP performance article

I have been asked by several friends and colleagues how to setup ORCA to graph arbitrary data. Since it’s impossible to explain this in it’s entirety to everyone that asks, I decided to write an article for SysAdmin to describe the steps required to setup ORCA. The article is titled LDAP Performance Monitoring, and is in the current issue of SysAdmin magazine.

The article explains how to setup ORCA to graph LDAP performance statistics, and describes how to use the super useful ldap-ping.pl script. If you get a chance to read the article, please email me with feedback. I have several articles in the works, and would like to get as much constructive criticism as possible! This will help me write useful stuff in the future.