-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
Hi list,
please forgive cross posting, but I cannot specify the problem enough to
say whether list it fits perfectly, so I'll ask on both.
I have some machines based with following specs (see at the end of the
email).
They run CentOS 5.4 x86_64 with the latest patches applied, Xen-enabled
and should host one or more domUs. I put the domUs' storage on LVM, as I
learnt ages ago (what never caused any problems) and is way faster than
using file-based 'images'.
However, there's something special about these machines: They have the
new WD EARS series drives, which use 4K sector sizes. So, I booted a
rescue system and used fdisk to start at sector 64 instead of 63 (long
story made short: Due to overhead causing the drive to do much more,
inefficient writes when starting at sector 63, the performance
collapses; with 'normal' geometry (sector 63), the drive achieves about
25MiByte/sec writes, with starting at sector 64 partition, it achieves
almost 100MiByte/sec writes):
[r...@server2 ~]# fdisk -ul /dev/sda
Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 64 2097223 1048580 fd Linux raid
autodetect
Partition 1 does not end on cylinder boundary.
/dev/sda2 209722418876487 8389632 82 Linux swap / Solaris
/dev/sda318876488 1953525167 967324340 fd Linux raid
autodetect
On top of those (two per machine) WD EARS HDs there's ``md'' providing
two RAID1, /boot and LVM, as well as swap per HD (i.e. non-RAIDed). LVM
provides the / partition as well as LVs for Xen domUs.
I have about 60 machines running that style and never had any problems.
They run like a charm. On these machines, however, domUs are *very*
slow, have a steady (!) load of about two -- 50% stating in 'wait' --
and all operations take ages, e.g. a ``yum update'' with the recently
released updates.
Now, can that be due to 4K issues I didn't see, nestet now in LVM?
Help is very appreciated.
Cheers,
Timo
- ---
Linux server2.blah.org 2.6.18-164.11.1.el5xen #1 SMP Wed Jan 20 08:06:04
EST 2010 x86_64 x86_64 x86_64 GNU/Linux
- ---
[r...@server2 ~]# cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 23
model name : Intel(R) Core(TM)2 Quad CPUQ9400 @ 2.66GHz
stepping: 10
cpu MHz : 1998.000
cache size : 3072 KB
physical id : 0
siblings: 1
core id : 0
cpu cores : 1
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36
clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm constant_tsc
pni monitor ds_cpl vmx smx est tm2 cx16 xtpr lahf_lm
bogomips: 6668.58
clflush size: 64
cache_alignment : 64
address sizes : 36 bits physical, 48 bits virtual
power management:
processor : 1
vendor_id : GenuineIntel
cpu family : 6
model : 23
model name : Intel(R) Core(TM)2 Quad CPUQ9400 @ 2.66GHz
stepping: 10
cpu MHz : 1998.000
cache size : 3072 KB
physical id : 1
siblings: 1
core id : 0
cpu cores : 1
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36
clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm constant_tsc
pni monitor ds_cpl vmx smx est tm2 cx16 xtpr lahf_lm
bogomips: 6668.58
clflush size: 64
cache_alignment : 64
address sizes : 36 bits physical, 48 bits virtual
power management:
processor : 2
vendor_id : GenuineIntel
cpu family : 6
model : 23
model name : Intel(R) Core(TM)2 Quad CPUQ9400 @ 2.66GHz
stepping: 10
cpu MHz : 1998.000
cache size : 3072 KB
physical id : 2
siblings: 1
core id : 0
cpu cores : 1
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36
clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm constant_tsc
pni monitor ds_cpl vmx smx est tm2 cx16 xtpr lahf_lm
bogomips: 6668.58
clflush size: 64
cache_alignment : 64
address sizes : 36 bits physical, 48 bits virtual
power management:
processor : 3
vendor_id : GenuineIntel
cpu family : 6
model : 23
model name : Intel(R) Core(TM)2 Quad CPUQ9400 @ 2.66GHz
stepping: 10
cpu MHz : 1998.000
cache size : 3072 KB
physical id : 3
siblings: 1
core id : 0
cpu cores : 1
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu tsc msr pae mce cx8 apic mtrr mca cmo
