Buffers in memory to disk would be dependent on how much cache the raid 
controller has yeah?

Justin.

On Wed, 21 Nov 2007, Mike Andres wrote:

> I'm curious about NUMBER_DATA_BUFFERS_RESTORE and duplication performance as 
> well.  Anybody know this definitively?
>
> ________________________________
>
> From: veritas-bu-bounces AT mailman.eng.auburn DOT edu on behalf of Peters, 
> Devon C
> Sent: Tue 11/20/2007 1:32 PM
> To: VERITAS-BU AT mailman.eng.auburn DOT edu
> Subject: Re: [Veritas-bu] T2000 vaulting performance with VTL/LTO3
>
>
>
> Chris,
>
> To me it looks like there's a 1Gb bottleneck somewhere (90MB/s is about all 
> we ever got out of 1Gb fibre back in the day).  Are there any ISL's between 
> your tape drive, your switch, and your server's HBA?  Also, have you verified 
> that your tape drives have negotiated onto the fabric as 2Gb and not 1Gb?
>
> When we had 2Gb LTO-3 drives on our T2000's, throughput to a single drive 
> toped out around 160MB/s.  When we upgraded the drives to 4Gb LTO-3, 
> throughput to a single drive went up to 260MB/s.  Our data is very 
> compressible, and these numbers are what I assume to be the limitation of the 
> IBM tape drives.
>
> Regarding buffer settings, my experience may not apply directly since we're 
> doing disk (filesystems on fast storge) to tape backups, rather than VTL to 
> tape.  With our setup we see the best performance with a buffer size of 
> 1048576 and 512 buffers.  For us these buffer sizes are mostly related to the 
> filesystem performance, since we get better disk throughput with 1MB I/O's 
> than with smaller ones...
>
> I'm also curious if anyone knows whether the NUMBER_DATA_BUFFERS_RESTORE 
> parameter is used when doing duplications?  I would assume it is, but I don't 
> know for sure.  If it is, then the bptm process reading from the VTL would be 
> using the default 16 (?) buffers, and you might see better performance by 
> using a larger number.
>
>
> -devon
>
>
> -------------------------------------
> Date: Fri, 16 Nov 2007 10:00:18 -0800
> From: Chris_Millet <netbackup-forum AT backupcentral DOT com>
> Subject: [Veritas-bu]  T2000 vaulting performance with VTL/LTO3
> To: VERITAS-BU AT mailman.eng.auburn DOT edu
> Message-ID: <1195236018.m2f.181149 AT www.backupcentral DOT com>
>
>
> I'm starting to experiment with the use of T2000 for media servers.  The 
> backup server is a T2000 8 core, 18GB system.  There is a Qlogic QLE2462 
> PCI-E dual port 4Gb adapter in the system that plugs into a Qlogic 5602 
> switch.  From there, one port is zoned to a EMC CDL 4400 (VTL) and a few HP 
> LTO3 tape drives.  The connectivity is 4Gb from host to switch, and from 
> switch to the VTL.  The tape drive is 2Gb.
>
> So when using Netbackup Vault to copy a backup done to the VTL to a real tape 
> drive, the backup performance tops out at about 90MB/sec.  If I spin up two 
> jobs to two tape drives, they both go about 45MB/sec.   It seems I've hit a 
> 90MB/sec bottleneck somehow.  I have v240s performing better!
>
> Write performance to the VTL from incoming client backups over the WAN 
> exceeds the vault performance.
>
> My next step is to zone the tape drives on one of the HBA ports, and the VTL 
> zoned on the other port.
>
> I'm using:
> SIZE_DATA_BUFFERS = 262144
> NUMBER_DATA_BUFFERS = 64
>
> Any other suggestions?
>
>
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