Re: [Veritas-bu] Tuning backups.

I thought I saw a 2 or 3% performance increase as well using 256k instead 
of 32 or 64 but after about 10-20 benchmarks it turned out the fastest I 
could write to an LTO-2 tape was 60 MiB/s, perhaps, with LTO-3/4- these 
tunables may make more of a difference.

Justin.

On Fri, 12 Oct 2007, Scott Jacobson wrote:

> For Linux,
>
> (LTO II)
>
> In the /usr/src/linux-2.6.5-7.282/drivers/scsi location, I've modified (as 
> per the Veritas performance options) the st_options.h file.
>
> default:
> #define ST_FIXED_BUFFER_BLOCKS 32
> new:
> #define ST_FIXED_BUFFER_BLOCKS 64
>
> to match the default 64K default of BPTM.
>
> I've seen maybe a 2% or 3% increase in performance, not much, but I'll take 
> anything I can get.
>
> -sj
>
>
>>>> Justin Piszcz <jpiszcz AT lucidpixels DOT com> 10/12/2007 4:48 PM >>>
> I have and there are more options too you can set, as long as you set the
> NUM_BUFFERS and SIZE_BUFFERS, those give optimal results, I was not able
> to increase the bandwidth to the (LTO-2) tapes I was testing using any of
> the st parameters.
>
> Justin.
>
> On Fri, 12 Oct 2007, Andrew Stueve wrote:
>
>> Was there any resolution here?  Anyone test this by adding to the boot
>> param line?
>>
>> Adding something like:  st=buffer_kbs:256,max_buffers:6
>>
>> Anyone? Beuhler?
>>
>> -Andrew
>>
>> Justin Piszcz wrote:
>>>
>>> On Wed, 5 Sep 2007, Justin Piszcz wrote:
>>>
>>>>
>>>> On Wed, 5 Sep 2007, Parker, Matthew wrote:
>>>>
>>>>> What type of benchmark testing are you looking for?
>>>>>
>>>>> -----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 
>>>>> Justin Piszcz
>>>>> Sent: Wednesday, September 05, 2007 4:36 AM
>>>>> To: veritas-bu AT mailman.eng.auburn DOT edu
>>>>> Subject: [Veritas-bu] Tuning backups.
>>>>>
>>>>> There are several ways to tune backups.
>>>>>
>>>>> 1. NET_BUFFER_SZ
>>>>> 2. SIZE_DATA_BUFFERS
>>>>> 3. NUM_DATA_BUFFERS
>>>>>
>>>>> While these help a little, I found by reading the NBU6 optimization 
>>>>> document I improved speed by 2x in some cases (need to do some more
>>>>> verification) using 256k buffers in the kernel (Linux) st driver rather 
>>>>> than the default of 32k and also using more of them.
>>>>>
>>>>> Anyone here do a LOT of benchmark testing?
>>>> So far, it would appear that using general optimizations in NetBackup
>>>> only help so much, such as the ones mentioned above with the exception
>>>> of NET_BUFFER_SZ, I still need to look into that one.
>>>>
>>>> The buffers in the kernel appear to help much more, in Linux 2.4 the
>>>> default buffers for the st tape driver are 32k and there's four of them.
>>>>
>>>> I want to know every possible tunable parameter and its effect on the
>>>> system for the fastest backup possible.
>>>>
>>>> Justin.
>>>>
>>>> _______________________________________________
>>>> Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
>>>> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
>>>>
>>>
>>> In particular:
>>>
>>> 9.3.1. st boot parameters
>>>
>>> st=xxx[,yyy] where xxx is one of the following:
>>> buffer_kbs:<n>
>>> write_threshold_kbs:<n>
>>> max_buffers:<n>
>>> max_sg_segs:<n>
>>>
>>> (The old boot parameters st=aa[,bb[,cc[,dd]]] supported but deprecated)
>>>
>>>
>>> http://www.linux.com/base/ldp/howto/SCSI-2.4-HOWTO/st.html
>>> _______________________________________________
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>>> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
>>>
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