From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <51DBFFC4.6070501@redhat.com> Date: Tue, 09 Jul 2013 14:19:16 +0200 From: Marian Csontos MIME-Version: 1.0 References: <51DBDDE8.3010206@redhat.com> In-Reply-To: Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] Very slow i/o after snapshotting 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 Cc: Zdenek Kabelac , Micky On 07/09/2013 01:51 PM, Micky wrote: >> Is this supposed to be a bug report ? > > Sorry for bashing the info. I was just answering the questions. LOL! > >> So far I've no idea about disks/tables in use, system/kernel in use, lvm >> version in use.... > > RHEL 6.4 kernel-2.6.32-358.el6 (also tested with self compiled 3.8) > lvm2-2.02.98-9.el6.x86_64 > Disk on external mega raid controller with ext4 How does it perform without snapshot? I have seen a sluggish RAID array when run out of battery. Is there a reason to use that big chunks? If the origin is seeing a lot of small dispersed writes using big chunk may multiply it manyfold (actually worst case 128-times: every 4k write generating 512k read from origin and then written to snapshot.) -- Marian > Running Xen hypervisor but tested without it as well > > _______________________________________________ > 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/ >