Although RAID is mostly a technology that is used in production environments, I have some friends that they use Raid to speed up their hard drives. Besides in stores, you can find some ” RAID Ready” boxes.
what is RAID?
For those who aren’t familiar with it, RAID (redundant array of independent disks, originally redundant array of inexpensive disks) is a storage technology (both for Disks and Databases) that combines multiple disk drive components into a logical unit. Data is distributed across the drives in one of several ways called “RAID levels”, depending on what level of redundancy and performance (via parallel communication) is required.
In simple words RAID helps us (by using two or more disks) to reduce hardware cost, speed up our environment and also is used for data replication to ensure consistency between redundant resources, such as software or hardware components, to improve reliability, fault-tolerance, or accessibility.
In RAID there is a number of standard schemes that have evolved over time which are referred to as levels. Gnome Disks will support RAID 0(stripe), 1(mirror), 4 (dedicated parity), 5 (distributed parity), 6 (double distributed parity), 10 (stripe of mirror).
Broadberry.co.uk gives a short description of each level:
RAID 0 is the fastest and most efficient array type but offers no fault-tolerance.
RAID 1 is the array of choice for performance-critical, fault-tolerant environments. In addition, RAID-1 is the only choice for fault-tolerance if no more than two drives are desired.
RAID 2 is seldom used today since ECC is embedded in almost all modern disk drives.
RAID 3 can be used in data intensive or single-user environments which access long sequential records to speed up data transfer. However, RAID-3 does not allow multiple I/O operations to be overlapped and requires synchronized-spindle drives in order to avoid performance degradation with short records.
RAID 4 offers no advantages over RAID-5 and does not support multiple simultaneous write operations.
RAID 5 is the best choice in multi-user environments which are not write performance sensitive. However, at least three, and more typically five drives are required for RAID-5 arrays.
RAID 6 is similar to RAID level 5 however it allows extra fault tolerance by using a second indipendent parity scheme.
RAID 10 is implemented as a striped array whose segments are RAID 1 arrays.
RAID 0+1 is a mirrored array whose drives are in a RAID 5 array.
Wikipedia is always a nice start up guide to everything including RAID.
first cut of the “Create RAID Array” in Gnome Disks
Now I’m wondering if the “Create RAID Array” dialog should also have a way for the user to create a filesystem since it’s what you want 95% of the time (the other 5% includes using the resulting RAID array as a member device for RAID or LVM). Answers on a postcard, please!
David presents :)
Double authorization is a bug!
But the good things in Gnome Disks don’t stop!
Gnome Disks Selections
David also worked in ways to make the use of Gnome Disks simpler without falling into the typical dialogs-inside-dialogs trap.
This kind of selections that are inspired from Gnome Boxes and Documents, will arrive also in Gnome Music, Gnome Videos, and there are some mockups also for Gnome Files. As you see they will be used in every context selection Gnome module. While this method is obviously a touch-screen friendly it also works (or it doesn’t bother if you don’t want to use it) pretty well with mouse and keyboard.
And don’t think that touch screens are only small screens! Touch screens could be also 42″ monitors that we can use with-the WoW amazing- Skeltrack or similar “Kinect” technologies that will become quite common in the short future.
David Zeuthen ends his presentation by saying:
Right now the + icon on the floating toolbar is what you want to use for “Create RAID Array” (there’s a tooltip saying so too; I’ll get a better icon or maybe even spell it out with text-button). Anyway, it will bring up a dialog where you can choose the RAID level, name and maybe technical things like chunk size and then press “Create”. The brush icon is for deleting multiple disks in one go (using secure erase if possible), of course there will be a confirmation dialog there too.
Oh, btw, in the future we can also totally re-use 95% of all this for +Btrfs multi-disk setups.
(Yes, this will only allow creating RAID arrays on whole disks and this is actually intended as the conventional wisdom out there suggests this is better than messing around with partitions. If you really want RAID on partitions you can of course still use mdadm(8) on the command-line all you want, we’ll support at least showing the array in the UI as usual. Anyway, whole-disk vs partitions isn’t the point of this post so please don’t waste space discussing it here – thanks!)
*This feature will (?) land in Gnome 3.8, March 2013.