Hello!
I've the great pleasure of having a Mylex AcceleRAID card (and the
dubious pleasure of having TWO AMI MegaRAID cards). I spent some time
benchmarking and tuning the AMI-based arrays a few weeks ago, heavily
guided by information reaped from this list's archives; now it's the
Mylex's turn. The Mylex's proc info is at the bottom of this (longish)
email.
First things first: THANK YOU LEONARD ZUBKOFF! That's both for writing a
sweet driver with plenty of /proc info and for posting lots of
information to this list. I've leaned heavily upon it for tuning both
the AMIs and the Mylex.
On to a question or two:
It was mentioned that adjusting segment size to 8K (leaving the stripe
size at 64k) can result in ~10% write speed increase. I've noticed in
some benchmarks that I've been doing that stride seems to relate more to
read speeds than to writes; particularly, with 8K segments and 64k
stripes, stride=16 gave me reads of ~10-12MB/s where stride=2 gave me
reads of ~44MB/s.
Q1: Can anyone concisely define the difference between segment size and
stripe size?
Q2: Is stride more read-critical than write-critical?
AMI doesn't allow you to set segment size, as far as I can see.
Q3: Am I not looking hard enough?
Q4: If they don't let me set it, is there any way to find out what
they've set it to?
I think that's enough questions for a bit. Meanwhile, I'll be posting
the results of my benchmarks later this afternoon; I'll pass on a URL at
that point.
Thanks!
--j
***** DAC960 RAID Driver Version 2.2.6 of 31 May 2000 *****
Copyright 1998-2000 by Leonard N. Zubkoff <[EMAIL PROTECTED]>
Configuring Mylex DAC960PRL PCI RAID Controller
Firmware Version: 4.07-0-07, Channels: 1, Memory Size: 16MB
PCI Bus: 0, Device: 9, Function: 1, I/O Address: Unassigned
PCI Address: 0xF4104000 mapped at 0xF8809000, IRQ Channel: 19
Controller Queue Depth: 128, Maximum Blocks per Command: 128
Driver Queue Depth: 127, Scatter/Gather Limit: 33 of 33 Segments
Stripe Size: 64KB, Segment Size: 8KB, BIOS Geometry: 255/63
SAF-TE Enclosure Management Enabled
Physical Devices:
0:0 Vendor: QUANTUM Model: ATLAS_V_36_SCA Revision: 0230
Serial Number: 143011950054
Disk Status: Online, 71720960 blocks
0:1 Vendor: QUANTUM Model: ATLAS_V_36_SCA Revision: 0230
Serial Number: 143011950912
Disk Status: Online, 71720960 blocks
0:2 Vendor: QUANTUM Model: ATLAS_V_36_SCA Revision: 0230
Serial Number: 143011951730
Disk Status: Online, 71720960 blocks
0:3 Vendor: QUANTUM Model: ATLAS_V_36_SCA Revision: 0230
Serial Number: 143011950380
Disk Status: Online, 71720960 blocks
0:4 Vendor: QUANTUM Model: ATLAS_V_36_SCA Revision: 0230
Serial Number: 143011950393
Disk Status: Online, 71720960 blocks
0:9 Vendor: VA Linux Model: Fullon 2x2 Revision: 1.01
Logical Drives:
/dev/rd/c0d0: RAID-5, Online, 286883840 blocks, Write Back
No Rebuild or Consistency Check in Progress
--
Jim Meyer, Geek At Large [EMAIL PROTECTED]
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