Re: LVM write performance

2011-08-30 Thread Dion Kant
On 08/20/2011 12:53 AM, Stan Hoeppner wrote: > On 8/19/2011 4:38 PM, Dion Kant wrote: > >> I now think I understand the "strange" behaviour for block sizes not an >> integral multiple of 4096 bytes. (Of course you guys already knew the >> answer but just didn

Re: LVM write performance

2011-08-19 Thread Dion Kant
On 08/14/2011 02:30 PM, Dion Kant wrote: > On 08/14/2011 01:23 PM, Dion Kant wrote: >> Forget >> about the previous results, they will be wrong because of libgcc stream >> buffering and I did not check how these buffers are actually written to >> kernel space. > libg

Re: LVM write performance

2011-08-14 Thread Dion Kant
On 08/14/2011 01:23 PM, Dion Kant wrote: > Forget > about the previous results, they will be wrong because of libgcc stream > buffering and I did not check how these buffers are actually written to > kernel space. libgcc uses writev to write out an array of buffers to kernel space Use

Re: LVM write performance

2011-08-14 Thread Dion Kant
On 08/14/2011 09:14 AM, Dion Kant wrote: > The good and problematic block sizes do not really coincide with the > ones I observe with dd, but the odd behaviour is there. When testing on Linux kernel 2.6.37.6-0.5-xen, I found that a sync() call did not give any guarantee that the buffe

Re: LVM write performance

2011-08-14 Thread Dion Kant
On 08/13/2011 03:55 PM, Stan Hoeppner wrote: > My explanation to you wasn't fully correct. I confused specifying no > block size with specifying an insanely large block size. The other post > I was referring to dealt with people using a 1GB (or larger) block size > because it made the math easier

Re: LVM write performance

2011-08-13 Thread Dion Kant
On 08/09/2011 07:13 PM, Stan Hoeppner wrote: > On 8/9/2011 9:12 AM, Dion Kant wrote: > >> Thanks for your remarks. The disk info is given below. Writing to the >> disk is oke when mounted, so I think it is not a hardware/alignment >> issue. However your remarks ma

Re: LVM write performance

2011-08-09 Thread Dion Kant
On 08/09/2011 06:30 AM, Stan Hoeppner wrote: > On 8/8/2011 11:03 PM, Stan Hoeppner wrote: >> On 8/8/2011 2:00 PM, Dion Kant wrote: >>> On 08/08/2011 03:33 PM, Stan Hoeppner wrote: >>>> On 8/8/2011 1:25 AM, Dion Kant wrote: >>>>> Dear list, >>&

Re: LVM write performance

2011-08-08 Thread Dion Kant
On 08/08/2011 03:33 PM, Stan Hoeppner wrote: > On 8/8/2011 1:25 AM, Dion Kant wrote: >> Dear list, >> >> When writing to a logical volume (/dev/sys/test) directly through the >> device, I obtain a slow performance: >> >> root@dom0-2:/dev/mapper# dd of=

LVM write performance

2011-08-07 Thread Dion Kant
, 122 MB/s Does anyone know what is going on? The configuration is as follows: Debian 6.0.2 Kernel 2.6.32-5-xen-amd64 Tests are on a partition on one physical disk Best regards, Dion Kant -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe"