XFileSharing Pro - Read/Write Speed

[Stefanzm]

Hello to everyone ,
Searched thru the forums , but most topics was about whats better raid 5 or raid 6 or raid 10 and so on.

I have specific technical question (i know that unless you have big servers with 8+ hdd`s in raid you cant help but still).

At raid 5 the write speed is better than raid 6.
At raid 1 write speed is better than raid 5 and 6.

However i was wondering what is the average reading speed on the raids (in numbers that is ) .
On raid 0 with 2 hdd`s 2TB i managed under linux to get around 130MB/s (not mbps) . Now i have raid 1 but dont have second raid1 to test the average speed.
Has anyone tested the read speed on raid 5 and raid 6 with 8+ hdd`s ?
Or even better has anyone tested on raid 50 and 60 ?

Thanks in advance for the information

P.S. Ofcourse i`m asking for file server not the http one

[ankurs]

i would never touch raid5 or raid0, too easy to loose data

if you want pure performance then use raid10, if you need space and reliability then use raid6 or 60

i cant give you exact numbers, because it will vary on each server

[trinsic]

Who cares about write performance, you're going to saturate your network port well before anything else.

8 x 2TB
RAID 10:
8TB - 360 MB/s write, 400 MB/s read

RAID-6:
12TB - 240 MB/s write, 360 MB/s read

RAID5 is too unsafe.

Just stuff as many disks in each server as you can, put a GigE port on each server and max out the network port.

[ufkabakan]

How to check this speeds from SSH?

I use "iostat" and it can give me another print.

[Stefanzm]

you can see the cache and buffered read speed with:
hdparm -ftT /dev/yourraid

Friends warned me that there is dangerous switches in this command so be careful to use ftT

However i`m not sure how specific is this command , sometimes it show weard numbers like :

root@****:~/cgi-bin# hdparm -ftT /dev/md6

/dev/md6:
Timing cached reads: 6420 MB in 2.00 seconds = 3211.04 MB/sec
Timing buffered disk reads: 86 MB in 3.00 seconds = 28.63 MB/sec

The catched in ram is normal to be very high , however i cant believe that 2TB sata can read only at 28MB/s.