Linked by Thom Holwerda on Tue 6th Dec 2005 13:18 UTC, submitted by cpina
"Although having this reputation, my question was: was a RAID 1 system too slow? Was it slower than not having any RAID? In fact, there are people that say that it is the other way round - these people say that having software RAID 1 is faster than having just one hard disk drive. In any case, who is right?" 
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RE: Silly RAID comments so far
by on Thu 8th Dec 2005 22:05
in reply to "Silly RAID comments so far"
Member since:RAID 1 isn't going to give you a performance benifit on write, but it can on read, think about it. You can read from a RAID 1 just as if it were a RAID 0.
It can, but in the case of Linux (which this benchmark was testing) it doesn't. As of the last time I checked, nobody had written the driver to take advantage of the fact that you could read striped from a mirrored array. This is too bad since it seems like an obvious potential benefit.
Member since:
Multiple different disks in raid will not help boost your performance or reliability. The slowest disk will be the bottle neck. Silly.
As someone who deals with a lot of seasoned administrators I can tell you on the enterprise level, software RAID 5 is used frequently. Software RAIDs can autoexpand to knew disks gracefully while the system is on with generic controllers. This is especially nice on Linux using EVMS. If your proprietary raid controller dies and the company that made it goes out of business, how do you get your data? With software RAID the data is not tied to the controller.
RAID 0 definately has performance benifits in software mode. In my own experience with two RAID 0 setups, the sequential read and write was almost twice as fast as a single disk in the array. There were only two disks in the RAID 0 setups.
RAID 0 can also give you an advantage in real world tasks, such as encoding raw AVI to disk. In my own experience I NEEDED a RAID to record raw AVI from tv at certain qualitys or my sound and video would get all skippy in the recorded version.
RAID 1 isn't going to give you a performance benifit on write, but it can on read, think about it. You can read from a RAID 1 just as if it were a RAID 0.