Quoting Herbert Poetzl <herbert@13thfloor.at>: > On Sat, Jun 14, 2003 at 02:45:11PM +0200, Svetoslav Slavtchev wrote: > > Quoting Herbert Poetzl <herbert@13thfloor.at>: > > > > > didn't say that this would be bad, only that > > > it live-locked my system at high load ... > > > the tenor on the list was: "highmem is bad" > > > so I turned it off, and, voila the system was > > > stable again ... > > > > snapshots + md + highmem is very bad > > if you don't use snapshots its perfectly OK > > I have to disagree, live-lock under high load is > not perfectly OK, at least not for me ... 8-) i never had a lock-up :) this is with lvm1 soft raid 0 &5 and xfs. (firstly 1Gb and from a week 1.5Gb) > > > another, yet unexplained issue, is that on > > > another system, 4 SCSI discs, form a RAID 5 > > > array (software) which gives about 35MB > > > throughput, but lvm 1.0.7 ontop of that md > > > only has about 18MB throughput ... > > > > I've a bit defferent figures from a onboard HPT374 4 ide chanels > with > > 4 IBM deskstars 80Gb, but i still lose 8-15Mb/s compared to plain md > : > > > > /dev/hda: > > Timing buffer-cache reads: 128 MB in 0.41 seconds =308.43 MB/sec > > Timing buffered disk reads: 64 MB in 1.42 seconds = 45.07 MB/sec > > [root@svetljo root]# hdparm -tT /dev/md13 > > > > /dev/md13: > > Timing buffer-cache reads: 128 MB in 0.41 seconds =316.05 MB/sec > > Timing buffered disk reads: 64 MB in 1.08 seconds = 59.26 MB/sec > > [root@svetljo root]# hdparm -tT /dev/data > > data data2 > > [root@svetljo root]# hdparm -tT /dev/data2/Movies > > > > /dev/data2/Movies: > > Timing buffer-cache reads: 128 MB in 0.41 seconds =316.05 MB/sec > > Timing buffered disk reads: 64 MB in 1.32 seconds = 48.30 MB/sec > > I posted my results a month ago, but I digged them > out again, because together with your results, it > sheds new light on that issue ... > > mine raw disc md(raid5) lvm on md > ----------------------------------------------------- > hdparm 14694.40 34129.92 18667.52 > dd 1024k 14988.22 34732.56 18647.98 > dd 32k 15516.06 33945.48 18862.67 > > yours raw disc md(raid5) lvm on md > ----------------------------------------------------- > hdparm 46151.68 60682.24 49459.20 > > in both cases the lvm lies about 3MB over the raw > disc throughput, regardless of the md values ... > > maybe this could lead to some explanation of this > issue ... unfortunately there was no reply to my > posting over the last month *sigh* hm this is really strange. but can we belive hdparm, i think no. i was getting ~55Mb/s on raid-0 with bonnie++ but hdparm gives between 58-68Mb/s. i probably have to try to free one of the md5 raids and run bonnie++ on it, it should give better/ trustable numbers best, svetljo _______________________________________________ linux-lvm mailing list linux-lvm@sistina.com http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
