Articles in Data
This is just a quick summary of the more popular rescue CDs out there. All of these are Unix-based bootable ISOs. Some are available as self-burning EXE files, which may be useful if you don’t …
This is a quick reminder on how to configure a Celerra filesystem for dual NFS/CIFS access where Windows-side permissions would translate correctly to the NFS side. By default, Celerra datamover will mount filesystems in “Native” mode. In this case, a file or folder created by a Windows user via the CIFS share will take on the default Unix permissions on the NFS side: 755 for folders and 644 for files.
Filled up filesystems is a recurring condition eating up sysadmin time on a regular basis. Some studies show that filesystems running out of space are responsible for most day-to-day issues handled by IT departments. Disk …
As we all know, Celerra and its kin can get a bit annoying with their “filesystem over 90%” warning emails. Enabling the “autoextend” feature for the filesystems is one option, but if you are a control …
Below is a simple script to test filesystem read/write performance using dd with varying blocksize parameter. This can be useful for testing local filesystems as well as network-mounted filesystems. The end result will be a …
The recent announcement from Suse Enterprise Linux that Btrfs was production-ready raised some suspicions. The last time I tested btrfs (not very long ago) the primary issues were excessive CPU utilization and filesystem space that seemed to disappear into nowhere. So, as a quick test, I put together an OpenSuse 12.2 (3.4.6-2.10-desktop, OpenSuse 12.2) 64-bit VM (ESX) with one dual-core vCPUs, 4GB RAM, the OS disk and a 6GB striped LVM filesystem consisting of 4 4-GB virtual disks.
The following is a brief collection of open-source and/or free tools I regularly use for various system recovery tasks. If the servers you work with have CD drives, I would recommend burning these images onto a CD or DVD. This would save you the trouble of messing with the boot options in the BIOS. More advanced versions of BIOS can mount remote ISO images and boot from those. In most cases, however, this approach requires using the dreaded Internet Explorer an requires Windows.
Recently I ran into a small problem: I needed to find recently-modified files in a very large NFS filesystem. One of the high-level folders contained dozens of sub-folders with thousands of files in each. There is a significant performance penalty associated with placing such directory structures on network-mounted filesystems. Running the “find” command at the top of the filesystem would have taken over an hour and the problem here was not available bandwidth, but the time it takes for the “find” to request and receive attribute information for each folder and file.
The following is a standard process for replacing a failed boot disk mirrored with SVM on a Solaris 10 Sun server. Your hardware must support hot-swappable disks for this process to be performed without booting into single-user mode.
The following is a quick how-to explaining the process of importing an external CSV file into an existing Excel spreadsheet. This approach can be very handy if your CSV data is updated regularly by some external application. Keeping the formatting in the spreadsheet and pulling fresh data from a separate CSV is the way to go. The instructions below are for Excel 2010 running on Windows 7 64-bit. Command syntax for other versions of Excel and other platforms may differ.
On servers with many filesystems calculating filesystem space utilization summary can get very tedious. Below is a simple script that will summarize all filesystems and provide you will the totals for allocated and used space in GB.
The following example shows how to reduce the size of a filesystem mounted on an LVM logical volume. The instructions below are only for non-root filesystems. No reboot is required, but the filesystem will need to be unmounted. So, if there are any user applications using this filesystem, they will need to be stopped and the users will need to log out.
The following is a brief overview of the process for adding LUNs to VXVM under Linux. In our example we have an RHEL 5 server with existing LUNs and VXVM volume groups. Two new LUNs with multipathing were allocated from SAN and need to be added to the system to grow one of the volumes and the corresponding filesystem.
Every time you use Facebook, you probably have a nagging feeling in the back of your head that someone other than your friends is reading your posts. You should trust that feeling. At the same time, keep in mind that Facebook is a tool designed primarily for sharing personal information with large groups of people you barely know. Facebook is not your personal diary or a substitute for SMS. You just need to assume that everything you post on Facebook inevitably will end up in the hands of someone you don’t like very much. And then you proceed based on that assumption.
Reboot your Unix servers after making any major changes to the production environment. Should an unexpected problem come up, it will be easier to deal with it when everything is still fresh in your mind and not six months down the road, when you have to do a reboot to replace a failed system board and suddenly discover that some application wouldn’t load, by which time you forgot all about this application and have to start with the first page of the admin guide.
I had to power-cycle my Windows 7 64-bit laptop. The bootup sequence looked normal and reached a point where I could see the black screen with the mouse cursor. After this stage my desktop would usually appears, but not this time. I could move the mouse and I could even establish a remote desktop connection to my laptop. But I could not log in. Every time it would reach the same point – the black screen with the mouse cursor – and it would stop.
The “not owner” error is displayed on the client system (usually Solaris) when attempting to mount an NFS share from a server. This error may appear even though the share is correctly exported and the client system has full access. If you are getting a “permission denied” error, then this article is not for you and you should check here instead.
How do you know if your computer has a virus? Is it connected to the Internet? Then it has a virus. Many computer viruses and other malicious applications are very resilient and will actively resist any attempts to deactivate and remove them. Some viruses can even delete your antivirus application or prevent it from working properly. Many viruses cannot be effectively removed once they are loaded in memory and active.
Until I branched out a few years ago from supporting Unix server to working with Linux clusters, I never really encountered this issue: you type “reboot”, “init 0″, or “shutdown” as root and… nothing happens. Or the system starts going down but then hangs on unmounting a filesystem or unloading a module. I think this happened once to a colleague of mine who was rebooting a Solaris server, but this is a common problem with Linux.
Recently I upgraded a client’s Vista computer (Toshiba Qosmio, 4Gb, Intel Core Duo P7350, 7200-RPM 200-Gb disk) from Vista Ultimate 64-bit to Windows 7 Ultimate 64-bit. Being a Unix sysadmin this is not something I usually do. How did the experience compare to upgrading HP-UX, Solaris or SLES? In a nutshell: I’d rather walk around all day in wet underwear than attempt to upgrade Vista ever again.
NetBackup is an enterprise-level distributed backup and recovery application. The environment consists of the master server, media server, storage library, networking hardware, and client agents. NetBackup supports a wide variety of Unix, Linux, VMS, and Windows systems. The original backup solution was developed by Control Data Corp., later acquired by Openvision, which gave the product its “NetBackup” name. NetBackup was then bought by Veritas and is currently owned and supported (poorly) by Symantec.
I am sure this will sound familiar: you are copying a large amount of data – either locally or over the network – and you are wondering how long it will take and if there is a way to make things go faster.You may be surprised, but it does matter what type of files you are copying: 1Gb-worth of many small files will take considerably longer to copy than two 500Mb files. The hardware you are using is an important consideration, but it’s not the only factor limiting data transfer speed.