On Fri, Jun 30, 2006 at 09:32:13AM +0200, Cristian Livadaru wrote:
> On Thu, Jun 29, 2006 at 06:15:23PM +0200, Dieter St?ken wrote:
> > Cristian Livadaru wrote:
> > > me again ... isn't there anybody that could give ANY hint on what's
> > > wrong?
> > >
> > > I did some test with dd and the result is terrible!
> > >
> > > LVM
> > > explendidos:/shared# dd if=/dev/zero of=test1.dd bs=64 count=1000
> > > 1000+0 records in
> > > 1000+0 records out
> > > 64000 bytes transferred in 20.019969 seconds (3197 bytes/sec)
> >
> > seems the data gets written synchronously without any buffering.
> > Thus each write is delayed until the data is really written to
> > disk. For a 5400 RPM disk you get 90 transactions per seconds.
> > This gives about 10 seconds for 1000 chunks. "bs=64" means
> > 64 bytes! so each sector will be written multiple times.
> > So may be the system even reads in each sector again each time
> > before writing it, thus it takes two turns which gives 20 seconds.
> >
> > Unfortunately I can't tell why this happens :-(
> >
> > May be "direct IO" takes place (like for oflags=direct),
>
> where could I check this?
>
> > or this is some configuration option of LVM, i don't know about.
> > Try using "hdparm" to see, if DMA etc. is enabled. Have a look
>
> no matter how it's set, the result is always the same.
> I could'nt find any usefull information in any logfiles, I enabled LVM
> verbose mode and debug output but still nothing was found.
>
> > into /var/log/messages or use "dmesg" for nay hardware problems.
> > I recently discovered the "blockdev" command. Do you use any special
> I have read in some posts on the mailinglist about blockdev but not
> quite sure on how I could use it to solve my problem.
>
> > ext3 feature? You may try "tune2fs -o journal_data_writeback".
> > If you don't have relevant data on the LV, you may try to write
> > to the LV device directly. Is it slow for read, too? try "hdparm -t"
>
> hdparm -t /dev/share/sharevg
>
> /dev/share/sharevg:
> Timing buffered disk reads: 146 MB in 3.01 seconds = 48.50 MB/sec
> HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate
> ioctl for device
>
> I tried tune2fs but it didn't get any better.
> I also dont understand why with kernel 2.4 I get about 5mb/s instead of
> the 350kb/s
> not that 5mb would be great but still, much better then 350kb/s
>
> Maybee I should mention that this is some "want-to-be" raid controler
> that was on the mainboard.
>
> 0000:00:0e.0 RAID bus controller: Triones Technologies, Inc. HPT374 (rev
> 07)
>
very strange, I just created a lvm on to other disks the size of this
lvm is only 1gb and I did the dd test in there and it was way better.
here the config of my slow LVM, 2x 300GB
cat /etc/lvm/backup/share
# Generated by LVM2: Fri Jun 9 18:26:30 2006
contents = "Text Format Volume Group"
version = 1
description = "Created *after* executing '/sbin/vgcfgbackup'"
creation_host = "esplendidos" # Linux esplendidos 2.4.27-2-386 #1 Thu
Jan 20 10:55:08 JST 2005 i686
creation_time = 1149877590 # Fri Jun 9 18:26:30 2006
share {
id = "6szXKe-QPvJ-t14I-kF13-0JSc-bevq-dv4KBL"
seqno = 2
status = ["RESIZEABLE", "READ", "WRITE"]
extent_size = 8192 # 4 Megabytes
max_lv = 0
max_pv = 0
physical_volumes {
pv0 {
id = "g3jfAR-Z2Ka-SCgr-08QB-8WBn-5g4h-jXLrn1"
device = "/dev/hde1" # Hint only
status = ["ALLOCATABLE"]
pe_start = 384
pe_count = 71541 # 279.457 Gigabytes
}
pv1 {
id = "kYQB4j-fYV9-3NUa-g0Sg-H4Bk-Kx5F-wRO9G1"
device = "/dev/hdg1" # Hint only
status = ["ALLOCATABLE"]
pe_start = 384
pe_count = 71541 # 279.457 Gigabytes
}
}
logical_volumes {
sharevg {
id = "KdvcJ9-ZLMP-AJYA-soGK-qHfy-UtrX-PpV9Kv"
status = ["READ", "WRITE", "VISIBLE"]
segment_count = 2
segment1 {
start_extent = 0
extent_count = 71541 # 279.457
Gigabytes
type = "striped"
stripe_count = 1 # linear
stripes = [
"pv0", 0
]
}
segment2 {
start_extent = 71541
extent_count = 71541 # 279.457
Gigabytes
type = "striped"
stripe_count = 1 # linear
stripes = [
"pv1", 0
]
}
}
}
}
and here the config of the new lvm on the other disks:
cat /etc/lvm/backup/vhostvg
# Generated by LVM2: Fri Jun 30 11:15:54 2006
contents = "Text Format Volume Group"
version = 1
description = "Created *after* executing 'lvcreate -L200M -nvm02swaplv
vhostvg'"
creation_host = "esplendidos" # Linux esplendidos 2.6.11.12-xen0 #3
Thu Jun 29 15:47:52 CEST 2006 i686
creation_time = 1151658954 # Fri Jun 30 11:15:54 2006
vhostvg {
id = "bZljKZ-0k6u-kuo5-4tGM-MxF2-oft4-R2R9mf"
seqno = 5
status = ["RESIZEABLE", "READ", "WRITE"]
extent_size = 8192 # 4 Megabytes
max_lv = 0
max_pv = 0
physical_volumes {
pv0 {
id = "6POjat-zX5c-q7g5-KeRm-2ZmG-CAv4-odYFrt"
device = "/dev/hdi1" # Hint only
status = ["ALLOCATABLE"]
pe_start = 384
pe_count = 29311 # 114.496 Gigabytes
}
pv1 {
id = "VaOcDQ-wyN5-5ahB-UF3y-zcTw-7e1U-PnJUnJ"
device = "/dev/hdk1" # Hint only
status = ["ALLOCATABLE"]
pe_start = 384
pe_count = 29311 # 114.496 Gigabytes
}
}
logical_volumes {
vm01lv {
id = "nfdL2Z-NzUL-K9Ci-EF4L-izCq-qbnl-ZI6foI"
status = ["READ", "WRITE", "VISIBLE"]
segment_count = 1
segment1 {
start_extent = 0
extent_count = 256 # 1024 Megabytes
type = "striped"
stripe_count = 1 # linear
stripes = [
"pv0", 0
]
}
}
vm01swaplv {
id = "byPo9V-48mm-lfts-HZ4a-D21I-Y7Qt-573te9"
status = ["READ", "WRITE", "VISIBLE"]
segment_count = 1
segment1 {
start_extent = 0
extent_count = 125 # 500 Megabytes
type = "striped"
stripe_count = 1 # linear
stripes = [
"pv0", 256
]
}
}
vm02lv {
id = "up70a7-RETo-RvPI-liCc-ptdc-1qjA-MXrnsG"
status = ["READ", "WRITE", "VISIBLE"]
segment_count = 1
segment1 {
start_extent = 0
extent_count = 125 # 500 Megabytes
type = "striped"
stripe_count = 1 # linear
stripes = [
"pv0", 381
]
}
}
vm02swaplv {
id = "RrkcHD-SjMW-q4iz-3gGB-kgqV-TPDj-k7Jrl5"
status = ["READ", "WRITE", "VISIBLE"]
segment_count = 1
segment1 {
start_extent = 0
extent_count = 50 # 200 Megabytes
type = "striped"
stripe_count = 1 # linear
stripes = [
"pv0", 506
]
}
}
}
}
the 2 other disks are also on the HPT IDE Raid controller ( which is
actualy not running as raid, I just use it for additional IDE ports )
Cris
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