From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l8MIRr8u015271 for ; Sat, 22 Sep 2007 14:27:53 -0400 Received: from pd2mo1so.prod.shaw.ca (idcmail-mo1so.shaw.ca [24.71.223.10]) by mx3.redhat.com (8.13.1/8.13.1) with ESMTP id l8MIRklF026430 for ; Sat, 22 Sep 2007 14:27:47 -0400 Received: from pd3mr5so.prod.shaw.ca (pd3mr5so-qfe3.prod.shaw.ca [10.0.141.12]) by l-daemon (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0JOS005S28IZAJ20@l-daemon> for linux-lvm@redhat.com; Sat, 22 Sep 2007 12:25:47 -0600 (MDT) Received: from pn2ml5so.prod.shaw.ca ([10.0.121.149]) by pd3mr5so.prod.shaw.ca (Sun Java System Messaging Server 6.2-7.05 (built Sep 5 2006)) with ESMTP id <0JOS00JTV8ISHF40@pd3mr5so.prod.shaw.ca> for linux-lvm@redhat.com; Sat, 22 Sep 2007 12:25:47 -0600 (MDT) Received: from mail.activenetwerx.com ([68.144.68.179]) by l-daemon (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0JOS0072Q8IRL9R2@l-daemon> for linux-lvm@redhat.com; Sat, 22 Sep 2007 12:25:39 -0600 (MDT) Received: from an-ex.ActiveNetwerx.int (an-ex.activenetwerx.int [192.168.5.3]) by mail.activenetwerx.com (Postfix) with ESMTP id B3F3328223 for ; Sat, 22 Sep 2007 12:56:40 -0600 (MDT) Date: Sat, 22 Sep 2007 12:25:33 -0600 From: "Joseph L. Casale" Message-id: <1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911@an-ex.ActiveNetwerx.int> MIME-version: 1.0 Content-type: multipart/alternative; boundary=_000_1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911anexActiveNet_ Content-language: en-US Subject: [linux-lvm] LVM Overhead Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: To: "'linux-lvm@redhat.com'" --_000_1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911anexActiveNet_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Hi, I am wanting to use LVM behind an iet iscsi target and I am wondering how m= uch overhead if any does LVM add? Would the performance degrade any, curren= tly I am exporting full unpartitioned discs and am happy with the performan= ce. From what I am reading now, I would likely partition the physical discs= and use that in LVM then export a volume. I am new to LVM but see some advantages long term to using it! Thanks! jlc --_000_1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911anexActiveNet_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Hi,
I am wanting to use LVM behind an iet iscsi target and I am wondering how m= uch overhead if any does LVM add? Would the performance degrade any, currently = I am exporting full unpartitioned discs and am happy with the performance. From = what I am reading now, I would likely partition the physical discs and use that = in LVM then export a volume.

I am new to LVM but see some advantages long term to u= sing it!

Thanks!
jlc

--_000_1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911anexActiveNet_-- From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l8OF5nV5003152 for ; Mon, 24 Sep 2007 11:05:49 -0400 Received: from shuttlerun.csg.stercomm.com (scidalsmtp02.csg.stercomm.com [204.214.3.25]) by mx3.redhat.com (8.13.1/8.13.1) with ESMTP id l8OF5lid023709 for ; Mon, 24 Sep 2007 11:05:47 -0400 Message-ID: <46F7D242.3030707@stercomm.com> Date: Mon, 24 Sep 2007 10:05:38 -0500 From: Chris Cox MIME-Version: 1.0 Subject: Re: [linux-lvm] LVM Overhead References: <1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911@an-ex.ActiveNetwerx.int> In-Reply-To: <1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911@an-ex.ActiveNetwerx.int> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: LVM general discussion and development Joseph L. Casale wrote: > Hi, > I am wanting to use LVM behind an iet iscsi target and I am wondering > how much overhead if any does LVM add? Would the performance degrade > any, currently I am exporting full unpartitioned discs and am happy with > the performance. From what I am reading now, I would likely partition > the physical discs and use that in LVM then export a volume. Overhead is negligible. I haven't seen any impact at all. > > > > I am new to LVM but see some advantages long term to using it! Definitely. > > > > Thanks! > jlc > -- Chris Cox Sr. Unix Sys Admin From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l8OFFx9A008685 for ; Mon, 24 Sep 2007 11:15:59 -0400 Received: from mail2.syneticon.net (mail.syneticon.net [213.239.212.131]) by mx3.redhat.com (8.13.1/8.13.1) with ESMTP id l8OFFqqe029963 for ; Mon, 24 Sep 2007 11:15:52 -0400 Received: from postfix1.syneticon.net (postfix1.syneticon.net [192.168.112.6]) by mail2.syneticon.net (Postfix) with ESMTP id E93ED53F45 for ; Mon, 24 Sep 2007 17:15:45 +0200 (CEST) Received: from localhost (filter1.syneticon.net [192.168.113.3]) by postfix1.syneticon.net (Postfix) with ESMTP id AEE809356 for ; Mon, 24 Sep 2007 17:15:44 +0200 (CEST) Received: from postfix1.syneticon.net ([192.168.113.4]) by localhost (mx03.syneticon.net [192.168.113.3]) (amavisd-new, port 10025) with ESMTP id tUKuX1n9K1dn for ; Mon, 24 Sep 2007 17:15:40 +0200 (CEST) Received: from [192.168.10.145] (xdsl-87-78-246-105.netcologne.de [87.78.246.105]) by postfix1.syneticon.net (Postfix) with ESMTP for ; Mon, 24 Sep 2007 17:15:40 +0200 (CEST) Message-ID: <46F7D49A.2090206@wpkg.org> Date: Mon, 24 Sep 2007 17:15:38 +0200 From: Tomasz Chmielewski MIME-Version: 1.0 Subject: Re: [linux-lvm] LVM Overhead References: <1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911@an-ex.ActiveNetwerx.int> <46F7D242.3030707@stercomm.com> In-Reply-To: <46F7D242.3030707@stercomm.com> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: LVM general discussion and development Chris Cox schrieb: > Joseph L. Casale wrote: >> Hi, >> I am wanting to use LVM behind an iet iscsi target and I am wondering >> how much overhead if any does LVM add? Would the performance degrade >> any, currently I am exporting full unpartitioned discs and am happy with >> the performance. From what I am reading now, I would likely partition >> the physical discs and use that in LVM then export a volume. > > Overhead is negligible. I haven't seen any impact at all. Quite the contrary - unless the default settings are not changed. By default, the readahead values for LVM volumes is quite low / for iSCSI, I always have to change it to get acceptable performance (one might want to replace the $HOSTNAME with the name of the PV, or define a separate list; "setra" values might need some experimenting, too): LVMS=$(/bin/ls /dev/$HOSTNAME/) for LVM in $LVMS do blockdev --setra 16384 /dev/$HOSTNAME/$LVM done -- Tomasz Chmielewski http://blog.wpkg.org From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l8OGYmLB024898 for ; Mon, 24 Sep 2007 12:34:48 -0400 Received: from shuttlerun.csg.stercomm.com (scidalsmtp02.csg.stercomm.com [204.214.3.25]) by mx3.redhat.com (8.13.1/8.13.1) with ESMTP id l8OGYkUH012521 for ; Mon, 24 Sep 2007 12:34:46 -0400 Message-ID: <46F7E720.4060304@stercomm.com> Date: Mon, 24 Sep 2007 11:34:40 -0500 From: Chris Cox MIME-Version: 1.0 Subject: Re: [linux-lvm] LVM Overhead References: <1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911@an-ex.ActiveNetwerx.int> <46F7D242.3030707@stercomm.com> <46F7D49A.2090206@wpkg.org> In-Reply-To: <46F7D49A.2090206@wpkg.org> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: LVM general discussion and development Tomasz Chmielewski wrote: > Chris Cox schrieb: >> Joseph L. Casale wrote: >>> Hi, >>> I am wanting to use LVM behind an iet iscsi target and I am wondering >>> how much overhead if any does LVM add? Would the performance degrade >>> any, currently I am exporting full unpartitioned discs and am happy with >>> the performance. From what I am reading now, I would likely partition >>> the physical discs and use that in LVM then export a volume. >> >> Overhead is negligible. I haven't seen any impact at all. > > Quite the contrary - unless the default settings are not changed. > > > By default, the readahead values for LVM volumes is quite low / for > iSCSI, I always have to change it to get acceptable performance (one > might want to replace the $HOSTNAME with the name of the PV, or define a > separate list; "setra" values might need some experimenting, too): > > > LVMS=$(/bin/ls /dev/$HOSTNAME/) > > for LVM in $LVMS > do > blockdev --setra 16384 /dev/$HOSTNAME/$LVM > done > > Hmmm, perhaps for iSCSI. But using fibre SAN, I saturate my 2Gbps link (almost 200MB/sec). -- Chris Cox Sr. Unix Sys Admin From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l8OGdRNR027478 for ; Mon, 24 Sep 2007 12:39:27 -0400 Received: from shuttlerun.csg.stercomm.com (scidalsmtp02.csg.stercomm.com [204.214.3.25]) by mx3.redhat.com (8.13.1/8.13.1) with ESMTP id l8OGdRxj015210 for ; Mon, 24 Sep 2007 12:39:27 -0400 Message-ID: <46F7E839.8040805@stercomm.com> Date: Mon, 24 Sep 2007 11:39:21 -0500 From: Chris Cox MIME-Version: 1.0 Subject: Re: [linux-lvm] LVM Overhead References: <1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911@an-ex.ActiveNetwerx.int> <46F7D242.3030707@stercomm.com> <46F7D49A.2090206@wpkg.org> <46F7E720.4060304@stercomm.com> In-Reply-To: <46F7E720.4060304@stercomm.com> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: LVM general discussion and development Chris Cox wrote: > Tomasz Chmielewski wrote: >> Chris Cox schrieb: >>> Joseph L. Casale wrote: >>>> Hi, >>>> I am wanting to use LVM behind an iet iscsi target and I am wondering >>>> how much overhead if any does LVM add? Would the performance degrade >>>> any, currently I am exporting full unpartitioned discs and am happy with >>>> the performance. From what I am reading now, I would likely partition >>>> the physical discs and use that in LVM then export a volume. >>> Overhead is negligible. I haven't seen any impact at all. >> Quite the contrary - unless the default settings are not changed. >> >> >> By default, the readahead values for LVM volumes is quite low / for >> iSCSI, I always have to change it to get acceptable performance (one >> might want to replace the $HOSTNAME with the name of the PV, or define a >> separate list; "setra" values might need some experimenting, too): >> >> >> LVMS=$(/bin/ls /dev/$HOSTNAME/) >> >> for LVM in $LVMS >> do >> blockdev --setra 16384 /dev/$HOSTNAME/$LVM >> done >> >> > > Hmmm, perhaps for iSCSI. But using fibre SAN, I saturate my > 2Gbps link (almost 200MB/sec). > > I check my local drives, they all use the default 1024.... Is setting the read ahead that big of a deal with just LVM? I would think if it's an issue, it's an issue everywhere. -- Chris Cox Sr. Unix Sys Admin From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l8OHqeLi004215 for ; Mon, 24 Sep 2007 13:52:40 -0400 Received: from mail2.syneticon.net (mail.syneticon.net [213.239.212.131]) by mx3.redhat.com (8.13.1/8.13.1) with ESMTP id l8OHqXHt029946 for ; Mon, 24 Sep 2007 13:52:34 -0400 Received: from postfix1.syneticon.net (postfix1.syneticon.net [192.168.112.6]) by mail2.syneticon.net (Postfix) with ESMTP id ACB854AB12 for ; Mon, 24 Sep 2007 19:52:27 +0200 (CEST) Received: from localhost (filter1.syneticon.net [192.168.113.3]) by postfix1.syneticon.net (Postfix) with ESMTP id 58BCD9356 for ; Mon, 24 Sep 2007 19:52:27 +0200 (CEST) Received: from postfix1.syneticon.net ([192.168.113.4]) by localhost (mx03.syneticon.net [192.168.113.3]) (amavisd-new, port 10025) with ESMTP id XZOLqtj26nI3 for ; Mon, 24 Sep 2007 19:52:24 +0200 (CEST) Received: from [192.168.10.145] (xdsl-87-78-246-105.netcologne.de [87.78.246.105]) by postfix1.syneticon.net (Postfix) with ESMTP for ; Mon, 24 Sep 2007 19:52:24 +0200 (CEST) Message-ID: <46F7F955.7070608@wpkg.org> Date: Mon, 24 Sep 2007 19:52:21 +0200 From: Tomasz Chmielewski MIME-Version: 1.0 Subject: Re: [linux-lvm] LVM Overhead References: <1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911@an-ex.ActiveNetwerx.int> <46F7D242.3030707@stercomm.com> <46F7D49A.2090206@wpkg.org> <46F7E720.4060304@stercomm.com> <46F7E839.8040805@stercomm.com> In-Reply-To: <46F7E839.8040805@stercomm.com> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: LVM general discussion and development Chris Cox schrieb: (...) >>> LVMS=$(/bin/ls /dev/$HOSTNAME/) >>> >>> for LVM in $LVMS >>> do >>> blockdev --setra 16384 /dev/$HOSTNAME/$LVM >>> done >>> >>> >> Hmmm, perhaps for iSCSI. But using fibre SAN, I saturate my >> 2Gbps link (almost 200MB/sec). >> >> > > I check my local drives, they all use the default 1024.... > Is setting the read ahead that big of a deal with just LVM? > I would think if it's an issue, it's an issue everywhere. For me, the default was 256. I use that big readahead after a bit of benchmarking; perhaps it's very specific to my setup. -- Tomasz Chmielewski http://wpkg.org From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l8OI6gvC012399 for ; Mon, 24 Sep 2007 14:06:42 -0400 Received: from pd4mo1so.prod.shaw.ca (idcmail-mo1so.shaw.ca [24.71.223.10]) by mx3.redhat.com (8.13.1/8.13.1) with ESMTP id l8OI6U05006115 for ; Mon, 24 Sep 2007 14:06:36 -0400 Received: from pd3mr2so.prod.shaw.ca (pd3mr2so-qfe3.prod.shaw.ca [10.0.141.178]) by l-daemon (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0JOV00L5IWW1F670@l-daemon> for linux-lvm@redhat.com; Mon, 24 Sep 2007 12:04:49 -0600 (MDT) Received: from pn2ml9so.prod.shaw.ca ([10.0.121.7]) by pd3mr2so.prod.shaw.ca (Sun Java System Messaging Server 6.2-7.05 (built Sep 5 2006)) with ESMTP id <0JOV00MBEWW17F00@pd3mr2so.prod.shaw.ca> for linux-lvm@redhat.com; Mon, 24 Sep 2007 12:04:50 -0600 (MDT) Received: from mail.activenetwerx.com ([68.144.68.179]) by l-daemon (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0JOV00G3CWW1E211@l-daemon> for linux-lvm@redhat.com; Mon, 24 Sep 2007 12:04:49 -0600 (MDT) Received: from an-ex.ActiveNetwerx.int (an-ex.activenetwerx.int [192.168.5.3]) by mail.activenetwerx.com (Postfix) with ESMTP id 60CBB2821D for ; Mon, 24 Sep 2007 12:36:01 -0600 (MDT) Date: Mon, 24 Sep 2007 12:04:43 -0600 From: "Joseph L. Casale" Subject: RE: [linux-lvm] LVM Overhead In-reply-to: <46F7D49A.2090206@wpkg.org> Message-id: <1C8CF1EA1A5B5940B81B0710B2A4C93820128EDAB9@an-ex.ActiveNetwerx.int> MIME-version: 1.0 Content-language: en-US References: <1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911@an-ex.ActiveNetwerx.int> <46F7D242.3030707@stercomm.com> <46F7D49A.2090206@wpkg.org> Content-Transfer-Encoding: 8bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: 'LVM general discussion and development' Thanks guys! You'll have to bear with me here, but how and where do I run the commands you noted here to set this value? Thanks! jlc -----Original Message----- From: linux-lvm-bounces@redhat.com [mailto:linux-lvm-bounces@redhat.com] On Behalf Of Tomasz Chmielewski Sent: Monday, September 24, 2007 9:16 AM To: LVM general discussion and development Subject: Re: [linux-lvm] LVM Overhead Chris Cox schrieb: > Joseph L. Casale wrote: >> Hi, >> I am wanting to use LVM behind an iet iscsi target and I am wondering >> how much overhead if any does LVM add? Would the performance degrade >> any, currently I am exporting full unpartitioned discs and am happy with >> the performance. From what I am reading now, I would likely partition >> the physical discs and use that in LVM then export a volume. > > Overhead is negligible. I haven't seen any impact at all. Quite the contrary - unless the default settings are not changed. By default, the readahead values for LVM volumes is quite low / for iSCSI, I always have to change it to get acceptable performance (one might want to replace the $HOSTNAME with the name of the PV, or define a separate list; "setra" values might need some experimenting, too): LVMS=$(/bin/ls /dev/$HOSTNAME/) for LVM in $LVMS do blockdev --setra 16384 /dev/$HOSTNAME/$LVM done -- Tomasz Chmielewski http://blog.wpkg.org _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l8PFDmOv030525 for ; Tue, 25 Sep 2007 11:13:48 -0400 Received: from shuttlerun.csg.stercomm.com (scidalsmtp02.csg.stercomm.com [204.214.3.25]) by mx3.redhat.com (8.13.1/8.13.1) with ESMTP id l8PFDlq9000483 for ; Tue, 25 Sep 2007 11:13:48 -0400 Message-ID: <46F925A3.4060306@stercomm.com> Date: Tue, 25 Sep 2007 10:13:39 -0500 From: Chris Cox MIME-Version: 1.0 Subject: Re: [linux-lvm] LVM Overhead References: <1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911@an-ex.ActiveNetwerx.int> <46F7D242.3030707@stercomm.com> <46F7D49A.2090206@wpkg.org> <46F7E720.4060304@stercomm.com> <46F7E839.8040805@stercomm.com> <46F7F955.7070608@wpkg.org> In-Reply-To: <46F7F955.7070608@wpkg.org> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: LVM general discussion and development Tomasz Chmielewski wrote: > Chris Cox schrieb: ... >> I check my local drives, they all use the default 1024.... >> Is setting the read ahead that big of a deal with just LVM? >> I would think if it's an issue, it's an issue everywhere. > > For me, the default was 256. > > I use that big readahead after a bit of benchmarking; perhaps it's very > specific to my setup. > > Oh... I didn't say it wouldn't benefit, I just know in my case it's not a HUGE win... but it is significant, significant enough for me to want to experiment with the values and doing some benchmarking. 256? Whoa... that seems really low. -- Chris Cox Sr. Unix Sys Admin From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l8QGAho1029424 for ; Wed, 26 Sep 2007 12:10:43 -0400 Received: from shuttlerun.csg.stercomm.com (scidalsmtp02.csg.stercomm.com [204.214.3.25]) by mx3.redhat.com (8.13.1/8.13.1) with ESMTP id l8QGAgFZ029541 for ; Wed, 26 Sep 2007 12:10:42 -0400 Message-ID: <46FA847D.5010405@stercomm.com> Date: Wed, 26 Sep 2007 11:10:37 -0500 From: Chris Cox MIME-Version: 1.0 Subject: Re: [linux-lvm] LVM Overhead References: <1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911@an-ex.ActiveNetwerx.int> <46F7D242.3030707@stercomm.com> <46F7D49A.2090206@wpkg.org> <1C8CF1EA1A5B5940B81B0710B2A4C93820128EDAB9@an-ex.ActiveNetwerx.int> In-Reply-To: <1C8CF1EA1A5B5940B81B0710B2A4C93820128EDAB9@an-ex.ActiveNetwerx.int> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: LVM general discussion and development Joseph L. Casale wrote: > Thanks guys! > You'll have to bear with me here, but how and where do I run the commands you noted here to set this value? I'd probably create an init script and have it executed for a given runlevel after the mounts are done. Some distros have a mechanism to add "user" things to end of the init process, but if not, just grab an init script and mod it to do the blockdev commands you need (you could make it smart so that it does some sort of checking for valid names, etc.) > > Thanks! > jlc > > -----Original Message----- > From: linux-lvm-bounces@redhat.com [mailto:linux-lvm-bounces@redhat.com] On Behalf Of Tomasz Chmielewski > Sent: Monday, September 24, 2007 9:16 AM > To: LVM general discussion and development > Subject: Re: [linux-lvm] LVM Overhead > > Chris Cox schrieb: >> Joseph L. Casale wrote: >>> Hi, >>> I am wanting to use LVM behind an iet iscsi target and I am wondering >>> how much overhead if any does LVM add? Would the performance degrade >>> any, currently I am exporting full unpartitioned discs and am happy with >>> the performance. From what I am reading now, I would likely partition >>> the physical discs and use that in LVM then export a volume. >> Overhead is negligible. I haven't seen any impact at all. > > Quite the contrary - unless the default settings are not changed. > > > By default, the readahead values for LVM volumes is quite low / for > iSCSI, I always have to change it to get acceptable performance (one > might want to replace the $HOSTNAME with the name of the PV, or define a > separate list; "setra" values might need some experimenting, too): > > > LVMS=$(/bin/ls /dev/$HOSTNAME/) > > for LVM in $LVMS > do > blockdev --setra 16384 /dev/$HOSTNAME/$LVM > done > > > -- > Tomasz Chmielewski > http://blog.wpkg.org > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > > > > > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l8QH0hMn022704 for ; Wed, 26 Sep 2007 13:00:43 -0400 Received: from pd3mo1so.prod.shaw.ca (idcmail-mo1so.shaw.ca [24.71.223.10]) by mx3.redhat.com (8.13.1/8.13.1) with ESMTP id l8QH0gJu027701 for ; Wed, 26 Sep 2007 13:00:42 -0400 Received: from pd2mr4so.prod.shaw.ca (pd2mr4so-qfe3.prod.shaw.ca [10.0.141.107]) by l-daemon (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0JOZ005ZXJ7CU9A0@l-daemon> for linux-lvm@redhat.com; Wed, 26 Sep 2007 10:59:36 -0600 (MDT) Received: from pn2ml3so.prod.shaw.ca ([10.0.121.147]) by pd2mr4so.prod.shaw.ca (Sun Java System Messaging Server 6.2-7.05 (built Sep 5 2006)) with ESMTP id <0JOZ00646J7CTEB0@pd2mr4so.prod.shaw.ca> for linux-lvm@redhat.com; Wed, 26 Sep 2007 10:59:37 -0600 (MDT) Received: from mail.activenetwerx.com ([68.144.68.179]) by l-daemon (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0JOZ002Z8J78GXE1@l-daemon> for linux-lvm@redhat.com; Wed, 26 Sep 2007 10:59:32 -0600 (MDT) Received: from an-ex.ActiveNetwerx.int (an-ex.activenetwerx.int [192.168.5.3]) by mail.activenetwerx.com (Postfix) with ESMTP id AEA0428222 for ; Wed, 26 Sep 2007 11:31:09 -0600 (MDT) Date: Wed, 26 Sep 2007 10:59:28 -0600 From: "Joseph L. Casale" Subject: RE: [linux-lvm] LVM Overhead In-reply-to: <46FA847D.5010405@stercomm.com> Message-id: <1C8CF1EA1A5B5940B81B0710B2A4C93820455DF104@an-ex.ActiveNetwerx.int> MIME-version: 1.0 Content-language: en-US References: <1C8CF1EA1A5B5940B81B0710B2A4C9381DF6018911@an-ex.ActiveNetwerx.int> <46F7D242.3030707@stercomm.com> <46F7D49A.2090206@wpkg.org> <1C8CF1EA1A5B5940B81B0710B2A4C93820128EDAB9@an-ex.ActiveNetwerx.int> <46FA847D.5010405@stercomm.com> Content-Transfer-Encoding: 8bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: 'LVM general discussion and development' Thank you Chris! jlc -----Original Message----- From: linux-lvm-bounces@redhat.com [mailto:linux-lvm-bounces@redhat.com] On Behalf Of Chris Cox Sent: Wednesday, September 26, 2007 10:11 AM To: LVM general discussion and development Subject: Re: [linux-lvm] LVM Overhead Joseph L. Casale wrote: > Thanks guys! > You'll have to bear with me here, but how and where do I run the commands you noted here to set this value? I'd probably create an init script and have it executed for a given runlevel after the mounts are done. Some distros have a mechanism to add "user" things to end of the init process, but if not, just grab an init script and mod it to do the blockdev commands you need (you could make it smart so that it does some sort of checking for valid names, etc.) > > Thanks! > jlc > > -----Original Message----- > From: linux-lvm-bounces@redhat.com [mailto:linux-lvm-bounces@redhat.com] On Behalf Of Tomasz Chmielewski > Sent: Monday, September 24, 2007 9:16 AM > To: LVM general discussion and development > Subject: Re: [linux-lvm] LVM Overhead > > Chris Cox schrieb: >> Joseph L. Casale wrote: >>> Hi, >>> I am wanting to use LVM behind an iet iscsi target and I am wondering >>> how much overhead if any does LVM add? Would the performance degrade >>> any, currently I am exporting full unpartitioned discs and am happy with >>> the performance. From what I am reading now, I would likely partition >>> the physical discs and use that in LVM then export a volume. >> Overhead is negligible. I haven't seen any impact at all. > > Quite the contrary - unless the default settings are not changed. > > > By default, the readahead values for LVM volumes is quite low / for > iSCSI, I always have to change it to get acceptable performance (one > might want to replace the $HOSTNAME with the name of the PV, or define a > separate list; "setra" values might need some experimenting, too): > > > LVMS=$(/bin/ls /dev/$HOSTNAME/) > > for LVM in $LVMS > do > blockdev --setra 16384 /dev/$HOSTNAME/$LVM > done > > > -- > Tomasz Chmielewski > http://blog.wpkg.org > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > > > > > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/