Raid 5 Vs Raid 0 in read test

[Mir96TA]

I have 3 WD Balck 500 GiG HDD at my disposal.
1 TB is enough for me as a space.
So I can use use Raid 5.
Now My question is is Raid 5 is faster then Raid 0 in reading ?
I understand for writting I am putting load on south bridge so it
would be slower due to one bit is parity.
I am also thinking Intel ICR 9 which embeded can it handly the task ?

 

[Madwand1]

No, RAID 5 is never faster than RAID 0 in a good implementation / configuration. RAID 0 gives you another spindle with the same number of drives. Alternatively you can save the extra drive for another purpose and still match or exceed RAID 5's speed with the remaining 2.

RAID 0 of course sucks for data integrity and probability of total data loss, whereas RAID 5 gives you the opposite -- greater tolerance for hardware failure.

ICH9R can handle either fine, but you need to turn on write-back caching for improving RAID 5 writing speed.

 

[Emulex]

raid-5 would read from all drives but due to checksum overhead you'd probably get less throughput in that (3) small of a raid-5 compared to raid-0. its real close to raid-0/10 in read but i've mostly focused on 6 to 12 drive setups.

the ICH9R is incompetent for raid-5. it has no cache. raid-5 requires a double read/write and you'll see 3 drives in misery like 30-50mb/s write speed while they may read at 300-360mb/s.

do not use the ICH9R. do not want. Buy a real raid controller with a battery back write cache. save yourself alot of time and misery.

Make sure you enable TLER properly if you do decide to raid-anything on those black drives.

 

[Madwand1]

ICH9R is fine for RAID 5 sequential read/write. Of course there are some advantages to spending a few hundred more on a higher-end dedicated controller.

Here's the performance on a similar, older chipset.

http://i89.photobucket.com/alb...-3vs4-wb-on-vs-off.png

Edit: Those measurements were take some time ago with drives which weren't the fastest even then. Newer WD drives are much faster to start, so the results would be higher, and perhaps closer to hitting chipset limitations. But sustained 300-360 MB/s in 3-drive RAID 5 with these drives is probably impossible, regardless of controller.

 

[imported_Hok]

Thanks Emulex for the advice... i just have a question on ICHXR controllers there is no need for enabling TLER since its not real RAID hardware right? we can just reboot if there is a dropout... i;m just asking for info... of course should still enable TLER...

Thanks.

 

[Emulex]

TLER yes for any ich raid-5.

build your system.

hit the reset button (or power down) in windows or power it down (like your UPS has run out a juice) a few times. install a demo copy of win7.

see what happens. trust me i do this stuff one every server/pc i have so i know what's coming..


get back to us on that great ich raid-5.