Transcript Windows 2000 IO Performance Leonard Chung & Jim Gray 4/5/2000 Study Goals  Repeat and Extend the Riedel, et.

Windows 2000 IO Performance
Leonard Chung & Jim Gray
4/5/2000
1
Study Goals

Repeat and Extend the Riedel, et. al paper.
 Many things have changed:
– Software: Windows 2000 instead of NT4SP3
– Hardware: New, faster drives and standards

3 main testing scenarios:
– old-old: “old” machine with NT4SP6
– old-new: “old” machine with Win2000
– new-new: “new” machine with Win2000
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2
Hardware Configurations

“old” hardware:
– 333 MHz PII
– 4 x 7200 RPM UW SCSI drives
– 128 MB SDRAM

“new” hardware:
–
–
–
–
4/5/2000
2 x 733 MHz PIII
4 x 10,000 RPM Ultra160 SCSI drives
256 MB RDRAM
4 x 5400 RPM UltraATA/66 IDE drives on a
3ware card
3
Primary Test Tools
SQLIO – the primary test tool
 CacheFlush – buffered sequential
 DiskCache – PCI/host adapter
throughput
 Memspeed – memory subsystem

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Testing Methodology

Before each test:
– Drive formatted
– Test files copied in same order
– Test run

Sequential test files made to live on
outer edge of disk, giving disk’s max
performance and consistent results.
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Media Banding

Modern disks are zoned
– More bits stored on outer tracks +
constant angular velocity =
fast outer tracks
– We’ve measured inner tracks on some
drives being up to 40% slower than the
outer tracks
– A “normal” disk map…
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Media Banding
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Overall Findings

Changes in throughput performance
are incremental rather than radical
– Trendlines have the same general shape
– Most of Riedel’s model still holds
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Hardware Bandwidth (RAP)
System Bandwidth: What Riedel Saw
in megabytes per second (not to scale!)
30
9
per disk
72
140
Hard Disk | SCSI | PCI | Memory | Processor
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Hardware Bandwidth (PAP)
System Bandwidth Yesterday
in megabytes per second (not to scale!)
40
15
per disk
133
422
Hard Disk | SCSI | PCI | Memory | Processor
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Hardware Bandwidth (PAP)
System Bandwidth Yesterday
in megabytes per second (not to scale!)
40
15
per disk
The familiar
bandwidth
pyramid:
133
422
The farther
from the CPU,
the less
the bandwidth.
Hard Disk | SCSI | PCI | Memory | Processor
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Hardware Bandwidth (PAP)
System Bandwidth Today
in megabytes per second (not to scale!)
The familiar
pyramid is gone!
PCI is now the
bottleneck!
26
26
160
133
1,600
In practice,
3 disks can reach
saturation using
sequential IO
Hard Disk | SCSI | PCI | Memory | Processor
26
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Hardware Bandwidth (PAP)
System Bandwidth Today
Possible
solutions:
in megabytes per second (not to scale!)
26
26
26
160
532
1,600
A fatter, 64bit
66MHz PCI
bus
or…
Hard Disk | SCSI | PCI | Memory | Processor
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Hardware Bandwidth (PAP)
System Bandwidth Today
Possible
solutions:
in megabytes per second (not to scale!)
26
26
160
133
26
1,600
26
26
133
160
A fatter, 64bit
66MHz PCI
bus
or…
multiple PCI
busses
26
Hard Disk | SCSI | PCI | Memory | Processor
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Hardware Bandwidth (RAP)
System Bandwidth Today (reads)
Numbers we’ve seen
in megabytes per second (not to scale!)
24
each
98.5
98.5
975
Hard Disk | SCSI | PCI | Memory | Processor
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old-old:
NT4SP3 vs. NT4SP6
Unbuffered read and WCE writes no
longer show decrease in throughput
Buffered read bug is gone
Overheads are different

NT4SP3
NT4SP6
NT4SP3 Unbuffered Read Throughput
80 10
Read
Throughput (MB/s)
ms/MB)
(cpu (MB/s)
Overhead
Throughput
870
60
650
4
8
Read
Write
6
Write
(WCE)
Write
+ WCE
4
Write
40
30
20
2
Write
2
Read
10
0 0
4/5/2000
0
2
0
2
24 4
32 32 6464 128
4 8 8 8 1616 16 32
128 192
192
64
128
192
Request
Si Size
ze
(K(KB)
Bytes)
Request
Request
Size
(K-Bytes)
NT4SP6
Unbuffered
Read
NT4SP6
Buffered
Overhead
NT4SP6
Buffered
Throughput
10
9
10 850
9 7
8 640
7
5
6 30
4
5
4 320
3 2
2 110
1 0
throughput at various
request depths
Throughput
(MB/s)(MB/s)
Overhead
Throughput
(CPU ms/MB)
NT4SP3
Buffered
Throughput
NT4SP3
Buffered
Overhead
1 Fast Disk, Various Request Depths
10
write (WCE)
read
write
1 deep
3 deep
read
w rite 4 deep
w rice 8(WCE)
deep
0
2
2
2 4
4
8
16
32
64
8
32
64
4 Request
8 1616Size
32(KB)
64
Request
(KB)
Request Size
Size (KB)
128
128
128
256
256
256
16
old-new:
Windows 2000

Software: Major changes, minor
differences
– Dmio: The volume manager for Win2K
• More fixed overhead than ftdisk due to
longer code paths
• More features than ftdisk (dynamically size
volumes, etc.)
– In the end, performance is the same.
• Processors are fast enough that there are
more than enough cycles to spare.
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new-new:
Windows 2000

Hardware: The American Way
– Faster, bigger, cheaper
• Disks are now 4 times bigger and 3 times
faster.
• SCSI bus bandwidth has surpassed the PCstandard 32bit, 33MHz PCI bus bandwidth.
• Random IO is unaffected by the PCI
bottleneck.
• Additional SMP processor provided no
additional throughput gains.
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new-new:
Windows 2000 Scalability
PCI Bottleneck
Win2K Dynamic
1 disk unbuffered throughput
Win2K Dynamic
2 disk unbuffered throughput
20
read
write
write (WCE)
15
10
5
Throughput (MB/s)
Throughput (MB/s)
25
0
2
4
8
16
32
64
128
50
45
40
35
30
25
20
15
10
5
0
256
read
write
write (WCE)
2
4
8
Request Size (KB)
read
write
write (WCE)
60
50
40
30
20
10
64
128
4
8
16
32
64
Request Size (KB)
256
100
80
60
40
read
20
write (WCE)
0
0
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Win2K 3 disk Dynamic, 1 disk Basic
4 disk unbuffered throughput
Throughput (MB/s)
70
16
Request Size (KB)
Win2K Dynamic
3 disk unbuffered throughput
Throughput (MB/s)

128
256
2
4
8
16
32
Request Size (KB)
64
128
256 19
new-new:
Windows 2000 & IDE

The real IO revolution: RAID priced for the
masses!
 The good news:
– IDE disks are cheap
• We bought 5400 RPM IDE 27GB drives for $209
($7.75/GB) while our 10,000 RPM 18GB SCSI drive
cost $534 ($30/GB)
• IDE costs $3.17 per Kaps while SCSI costs $5.09 per
Kaps.
• Today, IDE is $6,500 per TB while SCSI costs $16,000
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new-new:
Windows 2000 & IDE

IDE Performance:
•However,
can provide
to
IDE IO/s vs. up
Depth
Atlas 10K SCSImultiple
IO/s vs. DepthIDE disks Fireball
180
180
60%
more
Kaps
for
the
same
price as a single
160
160
140
140
120
120
SCSI
disk.
100
100
IO/s
IO/s
– Single disk random IO performance on a
5400 RPM IDE is much slower than a
10,000 SCSI.
80
60
40
20
0
read
write
1
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2
4
8
Request Depth
16
32
80
60
40
20
0
read
write
1
2
4
8
Request Depth
16
32
21
new-new:
Windows 2000 & IDE

IDE Performance:
– Single disk sequential IO throughput on
a 5400 RPM IDE drive is 80% of the
more expensive 10,000 RPM SCSI drive.
Throughput (MB/s)
30
W in2K 1 disk 3w are IDE
unbuffered throughput
25
25
20
20
15
15
10
1 deep read
2 deep read
1 deep write (WCE)
5
0
2
4
8
16
32
64
128 256
Request Size (KB)
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Throughput (MB/s)
Win2K 1 disk SCSI
unbuffered throughput
1
2
1
2
10
5
deep
deep
deep
deep
read
read
w rite
w rite
0
2
4
8
16
32
64
128 256
Re que s t Size (KB)
22
new-new:
Windows 2000 & IDE

Price/Performance for IDE is hard to beat
– Performance
• For sequential and random IO, IDE is
price/performance leader
• Overhead for SCSI and 3ware/DMA IDE is the same.
– Capacity
• 69GB (~2.5 disks worth) of Quantum Fireball lct08s
costs the same as one Quantum Atlas 10K 18GB
disk.
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new-new:
Windows 2000 & IDE

The bad news about IDE
– The quality of IDE controllers varies
Revolutions are
being missed due
to slow controller
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new-new:
Windows 2000 & IDE

The bad news about IDE
Throughput (MB/s)
25
Western Digital Caviar 30GB
3ware unbuffered read throughput
20
Missing every
other revolution
15
10
1 deep
5
Missing multiple revolutions
0
2
4/5/2000
High controller
overhead is
causing the disk to
miss revolutions
at small request
sizes
4
8
16
32
Request Size (KB)
64
128
256
25
new-new:
Windows 2000 & IDE (3ware)

The bad news about IDE
– IDE RAID isn’t as mature as SCSI
• Driver bugs and incompatibilities
• Problems with multiple IDE drives
– IDE spec gives 18” as the max cable length:
getting cables to drives can be a chore
– Avoid master/slave: reliability and possibly
performance is lost
– No hot swap
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new-new:
Windows 2000 & IDE (3ware)

The bad news about IDE
– RAID isn’t as mature as SCSI
• 3ware’s card peaks out at 55MBps for reads
and 40MBps for writes; 3 disks for reads
and 2 for writes.
40
50
50
35
40
30
40
25
30
30
20
deep
111deep
deep
deep
22 deep
2
deep
deep
44 deep
4
deep
deep
88 deep
20
20
15
111000
00
0
unbuffered write
40
5
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Win2K 2 disk 3ware hardware RAID0
3 disk 3ware hardware RAID0
Win2K 4
unbuffered write
60
60
8 deep
22
2
44
4
88
1166
32
32
64
64
8
16
32
64
Request
Re que s t Size
Size (KB)
(KB)
1128
28
128
256
256
256
Throughput
Throughput
Throughput (MB/s)
(MB/s)
Throughput (MB/s)
Throughput
Throughput
(MB/s)
(MB/s)
45
60
60
Win2K 2
4 disk
are hardw
are RAID0
Win2K
disk 3w
3ware
hardware
RAID0
Win2K
3 disk
3ware
hardware
RAID0
unbuffered read
read
unbuffered
unbuffered read
50
50
35
30
40
40
25
30
30
20
1 deep
deep
121deep
deep
22deep
deep
4
deep
4 deep
deep
deep
884deep
20
20
15
10
0
11
0
5
00
0
8 deep
22
2
44
4
88
1166
32
64
8
16
32
64
Request
Re que s t Size
Size (KB)
(KB)
27 256
128
256
128
Where do we go from here?

Network IO over Gigabit
– OOB performance and slight tuning

Sqlio2: a complete rewrite of SQLIO
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And in conclusion…

NT4SP6
– Unbuffered requests at 2KB, 4KB
request sizes no longer have dip
– Buffered read request bug gone
– Buffered overhead appears to be lower

Windows 2000
– Despite dmio replacing ftdisk,
throughput remains unaffected
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And in conclusion…

new-new SCSI performance
– PCI is now the bottleneck with 3 drives able to
reach saturation

new-new IDE
– IDE shows a lot of promise: cheap storage and
good performance
– Difficulty lies with multiple disks
• IDE RAID cards not quite ready for prime time
• Physically wiring the drives
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