Regarding your article on "RAID Performance" in the November 2009 issue, how should the optimal stripe-width and stride be adjusted for RAID6 vs. RAID5? Any other considerations when applying your recommendations to RAID6?
Trevor Cordes
| LM |
"RAID Performance" author Ben Martin writes:
The stride size will depend on what you are doing on the filesystem. I've found the normal 64KB size to be OK for general use. Perhaps increase this size if you are planning to use the filesystem mainly for large files. I wouldn't try using smaller chunks than 64KB.
You might be able to get higher throughput for large files by moving to 256 or 512KB stride. See the software benchmarks in this article: http://www.linux.com/archive/articles/140734
The stripe-width should just be the stride times the number of data-bearing disks. If you have five disks in RAID-5:
stripe-width = 4 x stride
And for a five-disk RAID-6 array, the stride-width is 3 x stride.
As the article mentions, ext3 and XFS accept these parameters slightly differently.
I tried to participate in your survey, I but found it was closed. Your December 2009 issue must have come in late!
I have often bought your magazine, looking for articles of interest. Unfortunately, I have seldom found anything related to Mandriva in it, and hence I am not a subscriber.
As a fervent user of Mandriva, all the way back to Mandrake, I run two PCs, an HP notebook (all with Mandriva 2010), and an Asus Eee PC 710 with Limpus Light at home. I teach Linux in the AACC Australian Associated Computer Club Inc., which I founded 15 years ago. My PCs are fitted with two hard disk trays each, for both IDE and SATA, so I can test any new distro version that comes my way and help repair other people's non-Linux computers (hence the dual trays).
I have tried and tested Fedora, Ubuntu, Red Hat, Solaris, PCLinusOS, Mint, SUSE, and so on, and regardless of which one I try, I always return to Mandriva, which I find the most configurable distro of them all. KDE is my desktop. Self-taught, 75, retired and living alone; Linux has become one of my hobbies, giving great pleasure.
Hope this answers some of the questions you probably included in your survey.
You have a great "Ubuntu" magazine!
Edward
| LM |
Your letter gives us the opportunity to thank everyone who participated in our recent online survey - and to apologize to those who didn't receive notice of the survey in time. With rare exceptions, the tools and concepts described in the magazine are still fully up to date by the time you read the articles, but, as you noted, it is a little harder to get the word out on surveys and other online events.
Watch for another survey in late 2010. We'll try to give a little more lead time next time, but all readers should know that you needn't wait for a survey if you have something you want to tell us. Send your thoughts to letters@linux-magazine.com.
We agree that Mandriva is one of the great Linux distros. We try to include at least two Mandriva DVDs per year. Although we typically don't focus on Mandriva's impressive collection of indigenous admin utilities (or the distro-specific utilities of any other Linux, for that matter), most of our articles are related to Mandriva because the vast majority of Linux applications will run on any Linux variant.
Thanks for the feedback on Ubuntu User magazine. We like UU too. Readers who haven't yet experienced our new Ubuntu mag should watch their local newsstands or visit us online at http://www.ubuntu-user.com.