Hi

Comparing  these types of numbers are abit unfair. We have customers 
running 9840 and LTO-2. They have alot higher throughput than 8-12GB/hour 
over a GB nic.

For example, we have a customer running Netware. The TSM server is an AIX 
server(pSeries 615) connected to a 3584-L32 library with 3 LTO-2 drives. 
The Netware server has about 200GB of data. The AIX server has three 
100Mbs nic, bundled togheter in an Etherchannel interface(theoretic speed 
is 300Mbs or 30MB/s). The netware server is connected through 100Mbs 
ethernet(single adapter). The server have a restore time of about 5½ hours 
which means we have an hourly throughput of almost 40GB/hour. Average 
networkspeed is 11MB/s. The Netware server utilizes multi-session restore, 
which means it can mount multiple volumes at once for restores.

We have another customer running a pSeries 650 clustrer. The cluster is 
attached to a 3584-L32 library with 9 LTO-2 drives. The pSeries server is 
equipped with an Etherchannel interface which consists of 2 GB nics. 
During testing of a restore scenario on one of their Lotus Domino 
servers(300GB of data), they reached about 50MB/s restoring directly from 
tape. In this case, we didnt utilize multi-session restore, which meant 
that the single LTO-2 drive could deliver 180GB/hour.

Today, the new tape technologies can easily outrun disks. To match LTO-2 
drives against disks, you'll ned large, fiber-attached disk subsystems, 
with no other load than the TSM server load. Internal SCSI-disks can never 
outrun fiber-attached LTO-2 drives. The LTO-2 drive has a native speed of 
35MB/s, compressed around 50-70MB/s depending on the type of data. They 
also have dynamic speed, which means you dont get the back-hitch as long 
as you keep writing data with at least 15MB/s. We've seen theese drives 
push up to 90MB/s on database backups and restores. During the testing 
phase of the implementation, we had up to 380MB/s from the disks(two 
mirrored FAStT900 connected through 4 FC HBA:s with 34 15K 36.4GB fiber 
disks per FAStT system) and almost 650MB/s from the drives(9 LTO-2 drives 
connected through 4 FC HBA:s).

The speed of the drives is all about design. If you attach a large number 
of drives to a single FC HBA, you'll easily get back-hitch. With the LTO-2 
drives, a fair number of drives/adapter is around 3-4 / adapter.

Designing disk to match the tape drives is all about cost. S-ATA drives 
can never outrun LTO-2 drives, at least not when it comes to large files 
or database backups and restores. Designing FC disks to match the drives 
will mean the cost is 10 times the cost of the tape drives.

This is all my opinion, and I'm sure that there are others out there that 
dont agree.

Best Regards

Daniel Sparrman
-----------------------------------
Daniel Sparrman
Exist i Stockholm AB
Propellervägen 6B
183 62 TÄBY
Växel: 08 - 754 98 00
Mobil: 070 - 399 27 51



TSM_User <tsm_user AT YAHOO DOT COM> 
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
2004-09-22 04:27
Please respond to
"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>


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Subject
Re: D2D on AIX






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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