http://h71028.www7.hp.com/ERC/downloads/5982-9971EN.pdf

I think this is it-- it may have been LTO-2 and not LTO-3:

Results of HP testing with HP LTO2 tape drives
 Table 11.

 16                                 11,000          15
 24                                 3,000           16­17
 32                                 0               30­32
 48                                 0               30­32


On Thu, 1 May 2008, Justin Piszcz wrote:

Unfortunately not it was from 2003 regrding the new LTO-3 (when it was new) on HP's site, it was a great review/document.

16 for number_Data_buffers helped to 32, but after that it showed no

improvemnet and 256k was best size


On Thu, 1 May 2008, Esson, Paul wrote:

Justin,

Do you have a link or other reference to the HP doc?

Regards,

Paul Esson

-----Original Message-----
From: Justin Piszcz [mailto:jpiszcz AT lucidpixels DOT com]
Sent: 30 April 2008 22:38
To: Jason Slagle
Cc: veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Anyone have any tweaks for LTO-4 and emulex
cardsunder RHEL5?

Btw there was a good HP doc, 32 for the NUMBER_DATA_BUFFERS and 256k for

the SIZE_DATA_BUFFERS is the best.

32 (48) was not any better, but 32 > 16 was a definite gain in

performance.


Justin.

On Wed, 30 Apr 2008, Jason Slagle wrote:

Having just gone through that (Albiet with Qlogic) this is what I did:

Make sure the st driver is set to a reasonable buffer size (I did this

in

/etc/modprobe.conf):
options st buffer_kbs=1024

echo "1048576" >/usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS
echo "1048576" >/usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS_DISK
echo "16" >/usr/openv/netbackup/db/config/NUMBER_DATA_BUFFERS
echo "16" >/usr/openv/netbackup/db/config/NUMBER_DATA_BUFFERS_DISK

echo "kernel.shmmax = 268435456" >>/etc/sysctl.conf

echo "65536" >/usr/openv/netbackup/NET_BUFFER_SZ

Doing this, I am able to hit 70-80MB/s to the tape from my DSSU, and I

think

I COULD actually go faster, but my DSSU is limiting it.

Someone else amy have better values for these to improve it more - I

would

love to hear them also.

Jason

--
Jason Slagle
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On Wed, 30 Apr 2008, Justin Piszcz wrote:

I am only seeing 8-10MiB/s directly from RAM (/dev/shm) where if I

write

the same data to an LTO-3, I see regular speeds, 60-90MiB/s no

problems?

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