Hi.
On Fri, Jan 04, 2019 at 11:03:48PM -0500, rhkra...@gmail.com wrote:
> On Friday, January 04, 2019 08:23:59 AM Reco wrote:
> > # pvs
> > PV VG Fmt Attr PSize PFree
> > /dev/md10 nas lvm2 a-- 14.55t 10.43t
> >
> > # hdparm -Tt /dev/md10
> > /dev/md10:
> > Timing cached reads: 1224 MB in 2.00 seconds = 612.05 MB/sec
> > Timing buffered disk reads: 1210 MB in 3.00 seconds = 403.28 MB/sec
> >
> > # hdparm -Tt /dev/nas/root
> > /dev/nas/root:
> > Timing cached reads: 1224 MB in 2.00 seconds = 611.55 MB/sec
> > Timing buffered disk reads: 1154 MB in 3.00 seconds = 384.42 MB/sec
> >
> > I see a difference, but I's something I can live with.
>
> Thanks very much!
>
> I need to learn more about pvs (I did google the man page), but I assume the
> /dev/md10 and /dev/nas/root are two ways of referring to the same partition,
> one within LVM, and one not?
md10 is a RAID10 consisting of 4 HDDs. No partitions, just
straightforward block devices.
/dev/nas/root is a logical volume (/ filesystem in this case), it
resides on this md10, as 'pvs' output shows.
Storage hierarchy is a as follows (lsblk, same for sdb, sdc and sdd):
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 1 7.3T 0 disk
└─md0 9:0 0 7.3T 0 raid1
└─md10 9:10 0 14.6T 0 raid0
├─nas-root 254:2 0 15.3G 0 lvm /
So yes, both md10 and /dev/nas/root are two ways of referring to the
same set of bytes on disks.
Reco
