We are about to schedule some down time on a production ASE cluster to
add some additional mirrored LSM volumes to an existing service. The
volumes are approx. 54gb (HSZ70 stripe sets). The mirror sets are under
LSM control and mirrored across controllers.
I have done a few tests with creating and mirroring the volumes (on
200000 block volumes) just to get some timings I can use to extrapolate
to the 54gb volumes. I get some interesting (disappointing) results.
Let me explain:
#volassist -g tony -U fsgen make testvol 200000 mirror=yes rz14 rz30
Average time=44 seconds.
#volassist -g tony -U fsgen make testvol 200000 mirror=no rz14
#volassist -g tony mirror testvol rz30
Average time 39 seconds - 88% quicker than creating the volume with two
mirrors.
#volassist -g tony -U fsgen make testvol 200 mirror=no rz14
#volassist mirror testvol rz30
#volassist -g tony -f growto testvol 200000
Average time 43 seconds - virtually identical to creating the volume
with two mirrors.
Using the second example, this extrapolates roughly to a little under 6
hours to mirror up! A bit longer than I had hoped for.
I was disappointed that example 3 did not mirror up much faster. Under
HP-UX/LVM, creating a volume small, then adding a mirror (with the
volume small) then extending the mirrored logical volume to its required
size is virtually instantaneous.
Does anybody have any ideas how I can speed up the mirror process (apart
from doing it the day before!). Am I missing something here?
The volumes cant be in the process of mirroring (through unfortunate
experience) when they are added to the ASE service. The service restart
times out as the disk group fails to export due to uncompleted LSM
activity.
You either have to add the volumes (no mirrors) to the service and add
the disks which will contain the mirror plexes to the service. Allow
the service to restart then add the mirrors (what we ended up doing).
Or, mirror up the volumes and wait for the mirroring to complete before
adding them to the service.
Any help or advice is appreciated. Thanks in advance.
Tony
+-----------------------------------------------------------------+
| TONY MILLER - Systems Projects - VODAFONE LTD, Derby House, |
| Newbury Business Park, Newbury, Berkshire. |
+-------------+---------------------------------------------------+
| Phone | 01635-507687(local) |
| Work email | ANTHONY.MILLER_at_VF.VODAFONE.CO.UK |
| X.400 | G=ANTHONY; S=MILLER; C=GB; A=GOLD 400; P=VODAFONE |
| FAX | 01635-506709(local) |
+-------------+---------------------------------------------------+
Disclaimer: Opinions expressed in this mail are my own and do not
reflect the company view unless explicitly stated. The information
is provided on an 'as is' basis and no responsibility is accepted for
any system damage howsoever caused.
Received on Thu Feb 04 1999 - 16:49:19 NZDT