Pre-Install Best Practice (PBP)¶
This howto sets out to establish Best Practice prior to a Rockstor install. It has grown out of a number of suggestions on the Rockstor forum where problems have been encountered that might otherwise have been avoided. The basic premise is to first ensure that the hardware you are to install Rockstor on is fit for purpose and tested reasonably with the readily available tools.
Memory Test (memtest86+)¶
Built into the Rockstor installer (inherited from the upstream CentOS installer) is the famous memtest86+ boot option. This program is actually derived from the linux kernel itself, the core of the operating system that Rockstor is built on, and is a boot option within the Rockstor Troubleshooting installer menu. Memtest86+ is licensed under the GPL.
First select the Troubleshooting menu item on the initial boot screen of the installer:-
Use the Cursor Keys and then the Enter Key to select this entry.
The following options should then be displayed:
Then select the Run a memory test option to boot the machine into the memtest86+ system.
N.B. This memory test system will continue indefinitely until you either turn off the system, which is safe to do, or press the ESC Key. It is recommended that 2 full test cycles be completed however a single full pass of all available tests is better than no memory testing at all.
An effective memory test is likely not to be complete in less than a few hours, though this depends on the speed of the hardware involved and how many passes one is content with.
Memtest86+ Cautionary Note¶
Memtest86+ can place a very intense load on your system, especially if run in the new Multithreaded mode (version 5.01 and onwards via F2 on initial start) but a sufficiently cooled system should be able to execute this test indefinitely however if your system has cooling issues then it may lockup or even sustain damage. Please take care to monitor your systems temperate during this test. Version 5.01 and on have a built in CPU temperature monitor. If you find that your version of the Rockstor installer doesn’t include the 5 .01 or newer version of memtest86+ and you would like to monitor your CPU temperature then download a Pre-Compiled Bootable ISO from their official page and write it to a USB key in exactly the same way you do for a Rockstor install ISO.
Wiping Disks (DBAN)¶
A popular tool to securely erase HDDs prior to their deployment or disposal is Darils Boot and Nuke. This tools essentially writes to every part of a disks surface and in the process exercises the drive across it’s entire working area. This like the Memory Test (memtest86+) will stress the system; in this case the drives selected for wiping. The purpose here is to first remove all data on the existing drives and second to test that the drive is able to write to all it’s available sectors, it is often the case that a drive is unaware of an issue with itself, via the built in SMART system, until it attempts to write to a faulty sector. In fact this can trigger a drives build in ability to allocate spare sectors reserved for this very purpose.
Note that the zero fill fast option is probably sufficient for testing purposes but that there are many official options available. All options will take a considerable amount of time to complete, ie in the region of a few hours per drive.
It is not strongly recommended that any drives be tested this way prior to using them for Rockstor but is included here as an advisory procedure if you suspect a drive of having hardware issues.
DBAN Cautionary Note¶
The DBAN program / procedure will Irreversibly Erase all data. Use with caution and disconnect any drives that you wish not to be affected prior to booting into DBAN. Due to the comparatively limited write cycles of earlier generation SSD’s further consideration should be given prior to running DBAN on these devices due to it’s write heavy nature.
Check Integrity of Downloaded ISO File¶
If the original download is corrupt then all else that follows is likely to have problems. ISO is computer slang short for ISO9660 which is the International Organization for Standardization official definition of the structure of data on a CD/DVD. If this structure is wrong or the data contained within it is corrupt then problems are bound to follow. To avoid this there is a simple command that can be executed once the download of the Rockstor iso file is complete: that of checking it’s checksum.
A checksum is a mathematical abstraction of a data set, in this case our file, that is unique (near enough anyway). As a result of this it is possible to establish file corruption by comparing the published checksum of the official file with that calculated from the downloaded file. This in effect verifies the downloaded file as legitimate / free from corruption. Note however though that if you used the BitTorrent download option to acquire your install image then this check has already been done by way of the internal workings of the BitTorrent system. No harm in double checking though. If however you acquired your image by any other means then it is highly recommended that you check it’s md5sum. In the following operating system specific sections it is assumed that you have downloaded your Rockstor ISO file into the Downloads directory and have opened a system terminal ready to execute the appropriate command.
On a Linux system¶
The following built-in command is how to get the md5sum of your downloaded file on almost any linux system.
On an OSX system¶
Here we see the built-in command to use on an OSX system as used on modern Apple computers.
MD5 (Rockstor-3.8-11.iso) = fbb65344b31c7715807750e58e99f788
On an MS Windows system¶
Using the built-in tool available on MS Windows.
CertUtil -hashfile %userprofile%\Downloads\Rockstor-3.8-11.iso MD5
MD5 hash of file C:\Users\username\Downloads\Rockstor-3.8-11.iso: fb b6 53 44 b3 1c 77 15 80 77 50 e5 8e 99 f7 88 CertUtil: -hashfile command completed successfully.
Checking the Install Media¶
Once you have created the USB or in deed the CD / DVD by your chosen method: see Making a Rockstor USB install disk in our Quick start guide there is one final measure one can take to ensure the the install media is as expected. That is to choose the Test this media & install Rockstor option on the initial boot screen of the installer:-
Using this option the installer will first check that it can successfully read the contents of the USB key or CD / DVD and only proceed if the integrity check of what it reads succeeds. Note that this does take additional time but not more than a few minutes on modern USB hardware.
The purpose of this test is two fold as it is not only checking the contents of the install media but also the computers ability to read that contents.