Hello people. I have been refered to this list from the lvm list. I have 2 disk in lvm and some logical volumes with mirroring. I did some tests but i wonder if it could also work as a raid1, i mean a parallel scheduller as told in HP-UX docs but for linux. I want to have the read speed benefit of having a mirrored lvolume as with raid1. Is it possible and stable at current time? if so, how? I couldnt find anything on the net, and nobody could answer on linux-lvm list. Thanks in advance. Diego 2009/7/16 <malahal@xxxxxxxxxx>: > Diego Jacobi [jacobidiego@xxxxxxxxx] wrote: >> Hi. >> >> Sry for retry but the lvm list is my last resource. > > Try dm-devel mailing list. Linux LVM is based on device mapper > framework. > >> Does Linux-LVM have Parallel scheduler mode for mirroring at all? >> If yes, how do you set it up, or check if it is enabled? > > Writes happen in parallel, of course! At the moment it only reads from > the default mirror leg (unless the default leg is broken). There was > some patch for round-robin reading among mirrored legs, but it is not in > the upstream yet. > > --Malahal. > > _______________________________________________ > linux-lvm mailing list > linux-lvm@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > This are my tests: sda1 = /boot in disk 1, no lvm sdb1 = /boot in disk 2, no lvm data/data = lvm without mirroring data/root = lvm with mirroring linux-8mmd:~ # hdparm -t /dev/sda1 /dev/sda1: Timing buffered disk reads: 262 MB in 3.02 seconds = 86.83 MB/sec linux-8mmd:~ # hdparm -t /dev/sdb1 /dev/sdb1: Timing buffered disk reads: 174 MB in 3.03 seconds = 57.36 MB/sec linux-8mmd:~ # hdparm -t /dev/data/data /dev/data/data: Timing buffered disk reads: 272 MB in 3.02 seconds = 90.02 MB/sec linux-8mmd:~ # hdparm -t /dev/data/root /dev/data/root: Timing buffered disk reads: 278 MB in 3.02 seconds = 92.16 MB/sec As you can see, the read speed are mostly the same. This could mean a secuenced scheduler. And this is my system setup: lvm> version LVM version: 2.02.39 (2008-06-27) Library version: 1.02.27 (2008-06-25) Driver version: 4.14.0 linux-8mmd:~ # pvs PV VG Fmt Attr PSize PFree /dev/sda3 data lvm2 a- 537.11G 395.12G /dev/sda5 data lvm2 a- 996.00M 988.00M <--- Note 1 Gb, for log /dev/sdb3 data lvm2 a- 138.99G 118.99G linux-8mmd:~ # lvs -a -o +devices LV VG Attr LSize Origin Snap% Move Log Copy% Convert Devices data data -wi-ao 121.50G /dev/sda3(125) home data mwi-ao 10.00G home_mlog 100.00 home_mimage_0(0),home_mimage_1(0) [home_mimage_0] data iwi-ao 10.00G /dev/sda3(33788) [home_mimage_1] data iwi-ao 10.00G /dev/sdb3(2560) [home_mlog] data lwi-ao 4.00M /dev/sda5(1) root data mwi-ao 10.00G root_mlog 100.00 root_mimage_0(0),root_mimage_1(0) [root_mimage_0] data iwi-ao 10.00G /dev/sda3(31228) [root_mimage_1] data iwi-ao 10.00G /dev/sdb3(0) [root_mlog] data lwi-ao 4.00M /dev/sda5(0) test data -wi-a- 500.00M /dev/sda3(0) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
