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: 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/
