linux-lvm.redhat.com archive mirror
 help / color / mirror / Atom feed
From: Zdenek Kabelac <zkabelac@redhat.com>
To: LVM general discussion and development <linux-lvm@redhat.com>,
	Dale Stephenson <dalestephenson@mac.com>
Subject: Re: [linux-lvm] Performance penalty for 4k requests on thin provisioned volume
Date: Wed, 13 Sep 2017 22:19:21 +0200	[thread overview]
Message-ID: <d23b94a7-b5c5-4ee2-51c7-7dfa06cca3d2@redhat.com> (raw)
In-Reply-To: <C28D2468-1843-4019-A503-E566A305977D@mac.com>

Dne 13.9.2017 v 17:33 Dale Stephenson napsal(a):
> Distribution: centos-release-7-3.1611.el7.centos.x86_64
> Kernel: Linux 3.10.0-514.26.2.el7.x86_64
> LVM: 2.02.166(2)-RHEL7 (2016-11-16)
> 
> Volume group consisted of an 8-drive SSD (500G drives) array, plus an additional SSD of the same size.  The array had 64 k stripes.
> Thin pool had -Zn option and 512k chunksize (full stripe), size 3T with metadata volume 16G.  data was entirely on the 8-drive raid, metadata was entirely on the 9th drive.
> Virtual volume “thin” was 300 GB.  I also filled it with dd so that it would be fully provisioned before the test.
> Volume “thick” was also 300GB, just an ordinary volume also entirely on the 8-drive array.
> 
> Four tests were run directlyagainst each volume using fio-2.2.8, random read, random write, sequential read, sequential write.  Single thread, 4k blocksize, 90s run time.

Hi

Can you please provide output of:

lvs -a -o+stripes,stripesize,seg_pe_ranges

so we can see how is your stripe placed on devices ?

SSD typically do needs ideally write 512K chunks.
(something like  'lvcreate -LXXX -i8 -I512k vgname' )

Wouldn't be 'faster' to just concatenate 8 disks together instead of striping 
- or stripe only across 2 disk - and then you concatenate 4 such striped areas...

64k stripes do not seem to look like ideal match in this case of 3 disk with 
512K blocks

Regards

Zdenek

  reply	other threads:[~2017-09-13 20:19 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-13 15:33 [linux-lvm] Performance penalty for 4k requests on thin provisioned volume Dale Stephenson
2017-09-13 20:19 ` Zdenek Kabelac [this message]
2017-09-13 22:39   ` Dale Stephenson
2017-09-14  9:00     ` Zdenek Kabelac
2017-09-14  9:37       ` Zdenek Kabelac
2017-09-14 10:52         ` Gionatan Danti
2017-09-14 10:57         ` Gionatan Danti
2017-09-14 11:13           ` Zdenek Kabelac
2017-09-14 14:32             ` Dale Stephenson
2017-09-14 15:25       ` Dale Stephenson

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=d23b94a7-b5c5-4ee2-51c7-7dfa06cca3d2@redhat.com \
    --to=zkabelac@redhat.com \
    --cc=dalestephenson@mac.com \
    --cc=linux-lvm@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).