for AIX:

lsattr -l hdiskX -> look foor the queue_depth field values between 20 and 64 
make sense, 128 in some extreme cases
chdev -l hdiskX -a queue_depth=Y (but only if the vg is off-line)

I found that some drives only support a queue_depth of 1... in that case, you 
found your bottleneck.

On 21 okt 2010, at 18:57, Zoltan Forray/AC/VCU wrote:

> In reference to these recommendations, this is what one of my SAN folks
> said:
> 
> If "increasing the queue depth for the individual disks" is something you
> can do on a CLARiiON, it's not something I'm familiar with.  On the HBA
> (and if you can), you would do that from the host side (like with
> SanSurfer for Qlogic HBAs).
> 
> I have no idea what he might be referring to with "EMC voodoo
> application".
> 
> "iostat/vmstat" are unix host utilities.
> 
> Each of the two LUNs is spread out over 7 disks.  The 2 RAID Groups and
> the enclosure they are in are dedicated to Tivoli.
> 
> I've seen some references to using lots of smaller LUNs rather than a few
> big ones.  You have 2 5.5TB LUNs now.  We can try splitting each of those
> into 10-12 smaller LUNs.
> Zoltan Forray
> TSM Software & Hardware Administrator
> Virginia Commonwealth University
> UCC/Office of Technology Services
> zforray AT vcu DOT edu - 804-828-4807
> Don't be a phishing victim - VCU and other reputable organizations will
> never use email to request that you reply with your password, social
> security number or confidential personal information. For more details
> visit http://infosecurity.vcu.edu/phishing.html
> 
> 
> 
> From:
> "Strand, Neil B." <NBStrand AT LEGGMASON DOT COM>
> To:
> ADSM-L AT VM.MARIST DOT EDU
> Date:
> 10/19/2010 01:50 PM
> Subject:
> Re: [ADSM-L] Lousy performance on new 6.2.1.1 server with SAN/FILEDEVCLASS
> storage
> Sent by:
> "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
> 
> 
> 
> Zoltan,
>   You may need to increase the queue depth for the individual disks
> and/or the HBA attached to the disks.
>   Monitor both the server (iostat/vmstat) and the storage (EMC voodoo
> application) for latency and compare the results for consistency.  You
> may need to adjust the striping of your logical LUNs on the storage.  I
> have observed serious performance degradation on an older IBM ESS simply
> because the logical volumes were created on a single SSA rather than
> spread across the entire set of disks.
> 
> Cheers,
> Neil Strand
> Storage Engineer - Legg Mason
> Baltimore, MD.
> (410) 580-7491
> Whatever you can do or believe you can, begin it.
> Boldness has genius, power and magic.
> 
> 
> -----Original Message-----
> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf 
> Of
> Zoltan Forray/AC/VCU
> Sent: Tuesday, October 19, 2010 9:15 AM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: [ADSM-L] Lousy performance on new 6.2.1.1 server with
> SAN/FILEDEVCLASS storage
> 
> Now that I have ventured into new territory with this new server (Linux
> 6.2.1.1), I am experiencing terrible performance when it comes to moving
> data from disk (FILEDEVCLASS on EMC/SAN storage) vs my other 6.1 and 5.5
> servers.
> 
> With the server doing nothing but migrating data from this SAN based
> stgpool to TS1130 tape, I am seeing roughly 700GB being moved in a
> 12-hour
> period.  On my other, internal disk based TSM servers, I move
> multiple-terabytes per day/24-hours.
> 
> So, where should I focus on why this is so slow?  Is it because I am
> using
> SAN storage?  How about the FILEDEVCLASS vs fixed, pre-formatted volumes
> (like every other server is using)?
> 
> Or is this normal?  If it is, I am in for some serious problems.  One of
> these servers is expected to replace an existing 5.5 server that
> processes
> 20TB+ of backups, per week (no, I can not go straight to tape due to the
> type of backups being performed).
> 
> Suggestions?  Thoughts?
> Zoltan Forray
> TSM Software & Hardware Administrator
> Virginia Commonwealth University
> UCC/Office of Technology Services
> zforray AT vcu DOT edu - 804-828-4807
> Don't be a phishing victim - VCU and other reputable organizations will
> never use email to request that you reply with your password, social
> security number or confidential personal information. For more details
> visit http://infosecurity.vcu.edu/phishing.html
> 
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-- 
Met vriendelijke groeten/Kind Regards,

Remco Post
r.post AT plcs DOT nl
+31 6 248 21 622