Hello, Tuesday, August 12, 2008, 5:53:26, David S. Broome wrote: > Hello - This is a best practices style question. > LVM with large arrays, one large or mutiple small PV's? > What is the suggested physical partition layout with large hardware > RAID arrays (is NAS or SAN) in the case where there can be one VG? > ie I have two Raid 5 Arrays that can either present one large > logical volume ie 3.5T and 2.9T each or a multiple smaller logical volumes ie 500G. I think from LVM side it doesn't matter if you have 10x PV of size 100 GB or 1 PV of size 1 TB. But it really depends on the SAN disk array you have and how it handles each virtual disk. Does it have queues, caches for each vdisk or for the entire array? For example for HP EVA arrays it is recommended to prefer smaller vdisks if possible. If array has for example queue for 100 outstanding requests per vdisk then it means 100 req for 1 TB vdisk, or 10x100 req for the same 1TB over 10 vdisks. The same applies also for OS. Don't know how are the defaults on linux, but for HP-UX we have to increase scsi queue depth for large disks. Also more PV is better when you somewhere in future want to shrink the VG... you just pvmove some data and can remove PV. This can't be done when you will have only one big PV. -- bYE, Marki _______________________________________________ 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/
