ADSM-L

Re: Disk Pool Volume Configuration

2005-08-17 17:59:20
Subject: Re: Disk Pool Volume Configuration
From: Pétur Eyþórsson <petur.e AT NYHERJI DOT IS>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Wed, 17 Aug 2005 21:57:05 +0000

Ben is absulutly correct here in my oppinion, raw volumes are beter.
Even though aix has the best I/O perfomance  is not as good as raw volumes.
you need be a good AIX administrator to tune the filesystem to be as good as raw. I do alsow agree with Ben on to take earch LUN a volume and to put them in one storage pool. you could put 2 volumes per LUN but it that depends on the perfomance on the SATA disks versus your network load and your tape perfomance.

 
           
 
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Kær kveðja / Best regards,
Pétur Eyþórsson  · Tæknilegur ráðgjafi eServer & Storage · Tivoli Advanced Storage Solutons Techical Expert
 · MCSE · SNIA Professional  ·  SNIA FC-SAN Practitioner  ·  IBM C AIX S · TSM CP · TSRM CP · TASS DP · IBM SAN P
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Ben Bullock <bbullock AT MICRON DOT COM>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>

17.08.2005 19:54
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"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>

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Re: [ADSM-L] Disk Pool Volume Configuration





                 This is a little off the topic of your question, but we don't
have our TSM server on a SATA SAN, just on SSA drives, so I'm not sure
what the best ways.
               
                I see you are making all those luns into 1 LV, putting a
filesystem on that vol and then putting it in the storage pool. I would
not do it that way. I would make each LUN a volume and then put it in
the storagepool, and not aggregate them together. TSM seems to use a
round-robin approach to using volumes in a diskpool, as you can see a
single session go from vol to vol, so by aggregating them into 1 big
device, I think you kind of blow this load distribution method that TSM
uses internally, as each session will hit that one filesystem/volume and
all the disks at the same time. Yucky performance would be my guess.

                In addition to that, from my experience, using the devices as
RAW volumes rather than filesystems gives you better throughput on a
typical install. If you are into VM tuning and calculating the
filesystem cacheing attributes, how to tune the read ahead buffers, etc,
etc, you can get filesystems to run better, but it takes more tinkering,
tweaking and monitoring.

                I just add the raw AIX volume right into the storage pool and it
works great. i.e. here is a storagepool with a bunch volumes. Each
volume is 1 18GB disks mirrored at the OS level and then put into the
storage pool as a raw device.


tsm: TSMSERV1A>q vol stg=db_diskpool

Volume Name                  Storage         Device         Estimated
Pct      Volume
                            Pool Name       Class Name      Capacity
Util      Status
                                                                (MB)

------------------------     -----------     ----------     ---------
-----     --------
/dev/rstglv01                DB_DISKPOOL     DISK            17,344.0
61.8     On-Line
/dev/rstglv02                DB_DISKPOOL     DISK            17,280.0
41.4     On-Line
/dev/rstglv04                DB_DISKPOOL     DISK            17,280.0
36.6     On-Line
/dev/rstglv05                DB_DISKPOOL     DISK            17,280.0
65.9     On-Line
/dev/rstglv06                DB_DISKPOOL     DISK            17,280.0
62.8     On-Line
/dev/rstglv07                DB_DISKPOOL     DISK            17,280.0
61.0     On-Line
/dev/rstglv08                DB_DISKPOOL     DISK            17,280.0
64.2     On-Line
/dev/rstglv09                DB_DISKPOOL     DISK            17,280.0
49.4     On-Line
/dev/rstglv10                DB_DISKPOOL     DISK            17,280.0
54.6     On-Line
/dev/rstglv13                DB_DISKPOOL     DISK            17,280.0
44.8     On-Line
/dev/rstglv15                DB_DISKPOOL     DISK            17,280.0
46.1     On-Line
/dev/rstglv16                DB_DISKPOOL     DISK            17,280.0
71.9     On-Line
/dev/rstglv17                DB_DISKPOOL     DISK            17,280.0
77.7     On-Line
/dev/rstglv18                DB_DISKPOOL     DISK            34,688.0
24.4     On-Line
/dev/rstglv19                DB_DISKPOOL     DISK            17,280.0
44.8     On-Line
/dev/rstglv20                DB_DISKPOOL     DISK            17,280.0
61.5     On-Line
/dev/rstglv27                DB_DISKPOOL     DISK            17,344.0
50.2     On-Line
/dev/rstglv28                DB_DISKPOOL     DISK            17,344.0
48.3     On-Line
/dev/rstglv30                DB_DISKPOOL     DISK            17,344.0
58.7     On-Line
/dev/rstglv31                DB_DISKPOOL     DISK            17,344.0
59.5     On-Line
/dev/rstglv32                DB_DISKPOOL     DISK            17,344.0
40.9     On-Line
/dev/rstglv33                DB_DISKPOOL     DISK            17,344.0
50.1     On-Line
/dev/rstglv34                DB_DISKPOOL     DISK            17,344.0
43.4     On-Line
/dev/rstglv35                DB_DISKPOOL     DISK            17,344.0
57.9     On-Line
...

You likely won't want to do OS mirroring for the TSM DB, for other
reasons talked about in the manuals and in the archives for this
listserv, but it's the only way for me to protect from disk failure
using JBOD. In your case, if the LUNs are RAID-5 or something under the
covers, there is no need to mirror at the OS. Just create a raw volume
on each LUN and put it into the diskpool.

My 2-cents.
Ben


-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Joni Moyer
Sent: Wednesday, August 17, 2005 1:28 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Disk Pool Volume Configuration

Hello,

I have just added fibre channel disk to our one AIX server.  Here are
the LUN's that were added to filesystem /tsmdev/stgpool1

CHRS044     /tsmdev/stgpool1

lun 175           100 GB
lun 178           100 GB
lun 181           100 GB
lun 184           100 GB
lun 187           100 GB
lun 190           100 GB
lun 193           100 GB
lun 199           100 GB
lun 204           100 GB
lun 210           100 GB

Total       1000 GB

What would be the best TSM volume configuration be?  I have 5 different
random disk storage pools where the data resides for 24 hours before
being swept to tape.  Would I create 10 storage pool volumes and put the
appropriate number of volumes/storage pool?  Or can I have more than 1
TSM volume per physical volume?

Thank you in advance!

I'm really trying to get the best performance and I'm hoping to
configure this disk properly the first time.

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