Jonathan,

We all appreciate the collaborative benefit of list participation, including
yours.  But do us all a favor please, and take your personal issues offline.


http://www.freebsd.org/doc/en/articles/mailing-list-faq/etiquette.html

Thanks. 


On 6/25/10 8:49 AM, "Martin, Jonathan" <JMARTI05 AT intersil DOT com> wrote:

> Great.  I would say that is your "baseline", and that is just about what I get
> out of 15x1TB SATA disks in a Raid-5 at 8 streams. What kind of Raid
> controller are you using?  What kind of block sizes on that raid volume? What
> kind, and how many physical disks are in your raid set? Is this a SAN or DAS?
> If it is a SAN, do you have other things on the same raid group? Are you using
> / what are your values in the touch files? Have you looked at your disk
> counters while the destaging is running? (Logical and Physical disk counters
> for individual disks.) Are you seeing high levels of disk queuing? Does your
> throughput to tape match the read/sec?
> 
> 35-40 MB/sec is not ideal, but I could consider it acceptable if you were
> using huge SATA disks. If you think you are not getting the performance you
> deserve from the hardware then I would suggest digging.  It took me two weeks
> to find the optimal settings that I run now.  In the mean time, don't listen
> to Ed.  There are plenty of users on this forum who have DSSUs running just
> fine. I for one have something like 12 sites running DSSUs without issue.
> 
> -J
> 
> -----Original Message-----
> From: WALLEBROEK Bart [mailto:Bart.WALLEBROEK AT swift DOT com]
> Sent: Thursday, June 24, 2010 11:19 PM
> To: Martin, Jonathan; veritas-bu AT mailman.eng.auburn DOT edu
> Subject: RE: [Veritas-bu] Destaging going slow
> 
> Martin,
> 
> Even when we fully format the DSSU disk and we then run 1 backup job to this
> disk and directly afterwards we duplicate it to tape we get these speeds
> (35-40MB/sec).  So at that time no fragmentation at all is involved.
> 
> Best Regards,
> Bart WALLEBROEK
> Backup Admin & Systems & Applications Management & Support Specialist 
> Enterprise Applications Delivery - Infrastructure Management
> 
> -----Original Message-----
> From: Martin, Jonathan [mailto:JMARTI05 AT intersil DOT com]
> Sent: Thursday, June 24, 2010 5:34 PM
> To: WALLEBROEK Bart; veritas-bu AT mailman.eng.auburn DOT edu
> Subject: RE: [Veritas-bu] Destaging going slow
> 
> I regularly push LTO3 to 100+MB/sec. It just depends on your configuration
> (hardware and software.) For example, I've got a 4TB Oracle DB that writes to
> a DSSU at 40MB/sec then destages to tape at 100+MB/sec.  I understand that you
> are running 1 deduplication job at a time to a single tape drive.  How many
> concurrent backups are you writing to the DSSU? That is where the
> "fragmentation" comes from. It's not so much fragmentation, as non-contiguous
> files that cause the majority of my speed issues.
> 
> -Jonathan
> 
> -----Original Message-----
> From: WALLEBROEK Bart [mailto:Bart.WALLEBROEK AT swift DOT com]
> Sent: Thursday, June 24, 2010 2:46 AM
> To: Martin, Jonathan; veritas-bu AT mailman.eng.auburn DOT edu
> Subject: RE: [Veritas-bu] Destaging going slow
> 
> Jonathan,
> 
> Actually we already tried out different sets of block sizes on the DSSU.  32
> seems to be the fastest we can find.  We do not use compression and there is
> no fragmentation whatsoever (newly formatted disk).  Only 1 duplication is
> done at a time (only 1 tape drive attached to the DSSU Media Server) while no
> backups are pointing to the DSSU while we perform the destaging.
> 
> But so far no luck.  Could this be due to the backend disk system where the
> DSSU disk is located on ?  Although we see some impressive speeds when backing
> up files from DSSU to that same tape drive.  We use an HP XP 20000 (Hitachi).
> 
> Best Regards,
> Bart WALLEBROEK
> Backup Admin & Systems & Applications Management & Support Specialist 
> Enterprise Applications Delivery - Infrastructure Management
> 
> 
> -----Original Message-----
> From: Martin, Jonathan [mailto:JMARTI05 AT intersil DOT com]
> Sent: Wednesday, June 23, 2010 3:59 PM
> To: WALLEBROEK Bart; veritas-bu AT mailman.eng.auburn DOT edu
> Subject: RE: [Veritas-bu] Destaging going slow
> 
> Format your DSSUs with a 64k block size.
> Use 64K block size on raid group.
> Disable compression (if you can't use 64k block size.)
> Lower the number of concurrent writes to the DSSU.
> Occasionally "clear" the DSSU to relieve fragmentation.
> 
> Clear the DSSU, write a single backup to the disk, then stream the backup to
> tape. Whatever performance you get from that single stream is the best you are
> going to get from that configuration.  Any additional concurrent writes will
> likely slow your performance.
> 
> We had a lively discussion on this topic a few weeks back. Here's a link to a
> post I made about fragmentation and wet blankets.
> 
> http://www.adsm.org/lists/html/Veritas-bu/2010-05/msg00029.html
> 
> -Jonathan
> 
> -----Original Message-----
> From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
> [mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of 
> WALLEBROEK
> Bart
> Sent: Wednesday, June 23, 2010 9:23 AM
> To: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: [Veritas-bu] Destaging going slow
> 
> We have a couple of windows (dedicated) Media Servers that act as NetBackup
> DSSU (Disk Staging Storage Unit) servers with each having from 4 to 16 TB of
> SAN disks.  Backing up to them is no issue and goes up to the limit of the
> network connected clients.  Destaging to tape (LTO4) however is slow (20 - 35
> MB/sec).
> 
> We have been in contact with Symantec where they advised us to lower the
> fragment size, change the data buffers size and numbers but we seem to get
> stuck to the current speed.  Backing up data from this DSSU disk to the tape
> drives goes up to physical tape speed limitation.
> 
> Does anyone have an idea where to look further to get to a reasonable speed ?
> 
> We currently are testing a Solaris DSSU server but we do not have numbers for
> that one.
> 
> Best Regards,
> Bart WALLEBROEK
> Backup Admin & Systems & Applications Management & Support Specialist 
> Enterprise Applications Delivery - Infrastructure Management
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