ADSM-L

Re: D2D on AIX

2004-09-22 05:50:31
Subject: Re: D2D on AIX
From: TSM_User <tsm_user AT YAHOO DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Tue, 21 Sep 2004 19:27:30 -0700
Good questions. Our real world example:We went from around 8 - 12 GB/hr restore 
off of tape to over 40 GB/hr from the file device classes.  Our test was a file 
server with a little over 300 GB of data.  The File server and the TSM server 
both had 1 GB NIC's.  Resource utilization was set to 10 in both cases.  The 
data was fragemented on tape for a little over a year for the first test.  The 
data was fragmented over disk for nearly 8 months.

Steve Harris <Steve_Harris AT HEALTH.QLD.GOV DOT AU> wrote: How does TSM access 
the data on file volumes? Does it keep an offset of the start of every file or 
aggregate?

If it does, then yes we could skip to the start of each file or aggregate. If 
it does not, then we need to read through the volume to find the file we are 
going to restore. Where we have a large number of concurrent restores 
happening, this could cause performance issues on the array.

Now TSM has some smarts on later technology tape drives that have block 
addressability and on-cartridge memory and can find a spot on the tape quickly, 
but does this translate to file volumes?

Regards

Steve.

>>> lau AT VTCAT.CC.VT DOT EDU 22/09/2004 4:49:55 >>>
True. Seek time is tiny compared to tape mounts. I am just concerned that
the TSM db has to keep track of thousands of volume. How much will it increase
the size of the db. Ours is already 90G at 70% utilized.

Eliza

>
> ==> In article <200409211619.i8LGJsbf018132 AT vtcat.cc.vt DOT edu>, Eliza 
> Lau writes:
>
> > What is the recommended volume size. I have seen someone mentioned 5G, but
> > then the number of volumes will explode from about 800 (current # of 3590
> > primary tapes) to thousands.
>
> Consider, this doesn't really cost you much. Seek time in a directory of
> thousands of files is still tiny compared to tape behavior.
>
> I probably wouldn't go as low as 5G, but 10G (much less than the average size
> of my 3590 vols) seems pretty reasonable to me. 20G is getting big, from my
> perspective.
>
>
>
> > How about keeping the staging space so clients backup to staging then
> > migrate to FILE volumes. Then every volume will be filled up.
>
>
> I like this, too.
>
>
> - Allen S. Rout
>



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