"Andrew B. Cramer" wrote:
>
> You would get good performance if you used a multi-channel controler.
>
> (.02) - Andy
>
I see no reason to require the use of multiple channels to get good
performance. I am using an eXtremeRAID controller from Mylex. I built
a machine with the 3 channel version of the AMI MegaRAID and put in 64MB
of cache. I set up only a single channel with 9 seagate barracude
7200rpm drives each with 1MB cache. I first tested it under RAID 0 and
was horified at the performance. Especially when I have two systems
with Buslogic BT958 UW SCSI controlers in systems running RAIDTools
.50. One is using 3 drives the other 4 and both of these systems beat
the MegaRAID. Now the logic here is that my software raid systems are
only using one channel and they are getting good performance..... So
why can't the MegaRAID do the same. I came to the conclusion, after a
few hours on tech support with AMI that it could not do better. AMI's
only argument was that "You just don't do all drives on one channel".
Well I wanted to, for specific reasons to our needs. So I opted to
return the card and get a Mylex eXtremeRAID controller. The cost was
negligable in difference, with the exception that you end up with 32MB
cache on the Mylex (upgradable to 64) vs the 64MB I had on the
MegaRAID. The eXtremeRAID has a StrongARM 233Mhz processor on it
instead of the old outdated i960 that the MegaRAID had running at
66Mhz. These are the performace numbers I see from Bonnie.
*****************************
First Category: SoftRAID (really poorly tuned. running on raidtools
.50)
-SoftRAID----------------------------
System: Dual Pentium II 450 512MB RAM
Linux RedHat 5.0
Software RAID (8K)
RAID 0 ( 3 18.2GB Seagate Barracuda Drives with 512K cache,
7200rpm)
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU
/sec %CPU
1900 11830 66.7 22894 36.5 8191 26.9 13714 62.5 22692 33.3
128.3 2.5
-SoftRAID----------------------------
System: Dual Pentium II 450 512MB RAM
Linux RedHat 5.2
Software RAID (8K)
RAID 0 ( 4 18.2GB Seagate Barracuda Drives with 512K cache,
7200rpm)
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU
/sec %CPU
1900 10961 62.8 18345 30.1 8027 28.0 13876 63.8 26628 44.2
113.2 2.8
*************************************
Second: MegaRAID (tuned to the best AMI could do for a single channel)
-MegaRAID------------------------
System: Pentium III 450 512MB RAM
Linux RedHat 6.0
AMI MegaRAID 438 with 64MB cache (64K, Direct IO, Adaptive,
Write Throug
h)
RAID 5 (8 18.2GB Seagate Barracuda Drives with 1024K cache,
7200rpm)
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU
/sec %CPU
1900 4524 25.0 4107 5.9 4044 12.2 13493 61.5 18491 22.5
228.0 6.6
-MegaRAID------------------------
System: Pentium III 450 512MB RAM
Linux RedHat 6.0
AMI MegaRAID 438 with 64MB cache (64K, Direct IO, Adaptive,
Write Throug
h)
RAID 0 (8 18.2GB Seagate Barracuda Drives with 1024K cache,
7200rpm)
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU
/sec %CPU
1900 10082 56.4 14297 21.1 7655 23.2 15964 73.4 21256 26.8
266.1 8.5
************************************
Third: eXtremeRAID (RAID 0, partially tuned... RAID 5 tuned well)
-eXtremeRAID---------------------
System: Pentium III 450 512MB RAM
Linux RedHat 6.0
Mylex eXtremeRAID with 32MB cache (64k, 8k & write through)
RAID 0 (8 18.2GB Seagate Barracuda Drives with 1024K cache,
7200rpm)
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU
/sec %CPU
1900 13455 74.2 26571 38.0 7951 22.2 20626 87.7 35327 37.4
283.9 4.0
-eXtremeRAID---------------------
System: Pentium III 450 512MB RAM
Linux RedHat 6.0
Mylex eXtremeRAID with 64MB cache (64k, 64k & write through)
RAID 5 (8 18.2GB Seagate Barracuda Drives with 1024K cache,
7200rpm)
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU
/sec %CPU
2000 15413 75.3 24303 20.5 11225 21.4 26140 97.1 47337 31.2
416.7 3.8
--
___________________________________________
( )
) Brian D. Haymore, Systems Administrator (
( Center for High Performance Computing )
) University of Utah (
( Email: [EMAIL PROTECTED] )
) Phone: (801) 585-1755 (
(___________________________________________)
