Justin Piszcz wrote:
[]
> Good to know/have it confirmed by someone else, the alignment does not
> matter with Linux/SW RAID.
Alignment matters when one partitions Linux/SW raid array.
If the inside partitions will not be aligned on a stripe
boundary, esp. in the worst case when the filesystem blo
On Sat, 29 Dec 2007, dean gaudet wrote:
On Tue, 25 Dec 2007, Bill Davidsen wrote:
The issue I'm thinking about is hardware sector size, which on modern drives
may be larger than 512b and therefore entail a read-alter-rewrite (RAR) cycle
when writing a 512b block.
i'm not sure any shipping
On Tue, 25 Dec 2007, Bill Davidsen wrote:
> The issue I'm thinking about is hardware sector size, which on modern drives
> may be larger than 512b and therefore entail a read-alter-rewrite (RAR) cycle
> when writing a 512b block.
i'm not sure any shipping SATA disks have larger than 512B sectors
Robin Hill wrote:
On Wed Dec 19, 2007 at 09:50:16AM -0500, Justin Piszcz wrote:
The (up to) 30% percent figure is mentioned here:
http://insights.oetiker.ch/linux/raidoptimization.html
That looks to be referring to partitioning a RAID device - this'll only
apply to hardware RAID or pa
On Thu, 20 Dec 2007, Bill Davidsen wrote:
Justin Piszcz wrote:
On Wed, 19 Dec 2007, Bill Davidsen wrote:
I'm going to try another approach, I'll describe it when I get results (or
not).
http://home.comcast.net/~jpiszcz/align_vs_noalign/
Hardly any difference at whatsoever, only on the
Justin Piszcz wrote:
On Wed, 19 Dec 2007, Bill Davidsen wrote:
I'm going to try another approach, I'll describe it when I get
results (or not).
http://home.comcast.net/~jpiszcz/align_vs_noalign/
Hardly any difference at whatsoever, only on the per char for
read/write is it any faster..?
Jon Nelson wrote:
That, for me, is the next question - how can one educate LVM about the
underlying block device such that logical volumes carved out of that
space align properly - many of us have experienced 30% (or so)
performance losses for the convenience of LVM (and mighty convenient
it is)
On Wed, Dec 19, 2007 at 10:31:12AM -0500, Justin Piszcz wrote:
> Some nice graphs found here:
> http://sqlblog.com/blogs/linchi_shea/archive/2007/02/01/performance-impact-of-disk-misalignment.aspx
Again, this is a HW RAID, and the partitioning is done _on top of_ the
RAID.
Gabor
--
--
On Wed, Dec 19, 2007 at 04:01:43PM +0100, Mattias Wadenstein wrote:
> From that setup it seems simple, scrap the partition table and use the disk
> device for raid. This is what we do for all data storage disks (hw raid)
> and sw raid members.
And _exactly_ that's when you run into the alignmen
On Wed, Dec 19, 2007 at 12:55:16PM -0500, Justin Piszcz wrote:
> unligned, just fdisk /dev/sdc, mkpartition, fd raid.
> aligned, fdisk, expert, start at 512 as the off-set
No, that won't show any difference. You need to partition _the RAID
device_. If the partitioning is below the RAID level, th
On 12/19/07, Michal Soltys <[EMAIL PROTECTED]> wrote:
> Justin Piszcz wrote:
> >
> > Or is there a better way to do this, does parted handle this situation
> > better?
> >
> > What is the best (and correct) way to calculate stripe-alignment on the
> > RAID5 device itself?
> >
> >
> > Does this also
Justin Piszcz wrote:
Or is there a better way to do this, does parted handle this situation
better?
What is the best (and correct) way to calculate stripe-alignment on the
RAID5 device itself?
Does this also apply to Linux/SW RAID5? Or are there any caveats that
are not taken into accou
On Wed, 19 Dec 2007, Robin Hill wrote:
On Wed Dec 19, 2007 at 09:50:16AM -0500, Justin Piszcz wrote:
The (up to) 30% percent figure is mentioned here:
http://insights.oetiker.ch/linux/raidoptimization.html
That looks to be referring to partitioning a RAID device - this'll only
apply to har
On Wed Dec 19, 2007 at 09:50:16AM -0500, Justin Piszcz wrote:
> The (up to) 30% percent figure is mentioned here:
> http://insights.oetiker.ch/linux/raidoptimization.html
>
That looks to be referring to partitioning a RAID device - this'll only
apply to hardware RAID or partitionable software RAID
On Wed, 19 Dec 2007, Bill Davidsen wrote:
I'm going to try another approach, I'll describe it when I get results (or
not).
http://home.comcast.net/~jpiszcz/align_vs_noalign/
Hardly any difference at whatsoever, only on the per char for read/write
is it any faster..?
Average of 3 runs tak
On Wed, 19 Dec 2007, Bill Davidsen wrote:
Justin Piszcz wrote:
On Wed, 19 Dec 2007, Bill Davidsen wrote:
Justin Piszcz wrote:
On Wed, 19 Dec 2007, Mattias Wadenstein wrote:
On Wed, 19 Dec 2007, Justin Piszcz wrote:
--
Now to my setup / question:
# fdisk -l /dev/sdc
Disk /dev
Justin Piszcz wrote:
On Wed, 19 Dec 2007, Bill Davidsen wrote:
Justin Piszcz wrote:
On Wed, 19 Dec 2007, Mattias Wadenstein wrote:
On Wed, 19 Dec 2007, Justin Piszcz wrote:
--
Now to my setup / question:
# fdisk -l /dev/sdc
Disk /dev/sdc: 150.0 GB, 150039945216 bytes
255 heads,
On Wed, 19 Dec 2007, Bill Davidsen wrote:
Justin Piszcz wrote:
On Wed, 19 Dec 2007, Mattias Wadenstein wrote:
On Wed, 19 Dec 2007, Justin Piszcz wrote:
--
Now to my setup / question:
# fdisk -l /dev/sdc
Disk /dev/sdc: 150.0 GB, 150039945216 bytes
255 heads, 63 sectors/track, 1824
On 12/19/07, Bill Davidsen <[EMAIL PROTECTED]> wrote:
> As other posts have detailed, putting the partition on a 64k aligned
> boundary can address the performance problems. However, a poor choice of
> chunk size, cache_buffer size, or just random i/o in small sizes can eat
> up a lot of the benefi
On 12/19/07, Bill Davidsen <[EMAIL PROTECTED]> wrote:
> As other posts have detailed, putting the partition on a 64k aligned
> boundary can address the performance problems. However, a poor choice of
> chunk size, cache_buffer size, or just random i/o in small sizes can eat
> up a lot of the benefi
Justin Piszcz wrote:
On Wed, 19 Dec 2007, Mattias Wadenstein wrote:
On Wed, 19 Dec 2007, Justin Piszcz wrote:
--
Now to my setup / question:
# fdisk -l /dev/sdc
Disk /dev/sdc: 150.0 GB, 150039945216 bytes
255 heads, 63 sectors/track, 18241 cylinders
Units = cylinders of 16065 * 512 =
On Wed, 19 Dec 2007, Jon Nelson wrote:
On 12/19/07, Justin Piszcz <[EMAIL PROTECTED]> wrote:
On Wed, 19 Dec 2007, Mattias Wadenstein wrote:
From that setup it seems simple, scrap the partition table and use the
disk device for raid. This is what we do for all data storage disks (hw raid)
On 12/19/07, Justin Piszcz <[EMAIL PROTECTED]> wrote:
>
>
> On Wed, 19 Dec 2007, Mattias Wadenstein wrote:
> >> From that setup it seems simple, scrap the partition table and use the
> > disk device for raid. This is what we do for all data storage disks (hw
> > raid)
> > and sw raid members.
> >
On Wed, 19 Dec 2007, Mattias Wadenstein wrote:
On Wed, 19 Dec 2007, Justin Piszcz wrote:
--
Now to my setup / question:
# fdisk -l /dev/sdc
Disk /dev/sdc: 150.0 GB, 150039945216 bytes
255 heads, 63 sectors/track, 18241 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk id
On Wed, 19 Dec 2007, Justin Piszcz wrote:
--
Now to my setup / question:
# fdisk -l /dev/sdc
Disk /dev/sdc: 150.0 GB, 150039945216 bytes
255 heads, 63 sectors/track, 18241 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x5667c24a
Device Boot Start
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