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Re: extremely slow write performance plaintext

To: Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx>
Subject: Re: extremely slow write performance plaintext
From: Cory Coager <ccoager@xxxxxxxxxxxxxxx>
Date: Tue, 25 Jan 2011 09:22:07 -0500
Banner: Set
Cc: xfs@xxxxxxxxxxx
In-reply-to: <4D36B5EA.6040603@xxxxxxxxxxxxxxxxx>
Organization: Davis Vision
References: <3205_1294953756_4D2F6D1C_3205_1943_1_4D2F6D1C.2060409@xxxxxxxxxxxxxxx> <20110113233527.6dca104d@xxxxxxxxxxxxxx> <18993_1294964274_4D2F9632_18993_1387_1_F79CF9ADB27B2646B59221B7355263830CC143B1@xxxxxxxxxxxxxxxxxxxxxxxx> <4D30A945.4060000@xxxxxxxxxxxxxxxxx> <27616_1295038110_4D30B69E_27616_233_1_4D30B69E.4020506@xxxxxxxxxxxxxxx> <4D30C7F3.3040105@xxxxxxxxxxxxxxxxx> <1779_1295360207_4D35A0CF_1779_747_1_4D35A0CF.9050503@xxxxxxxxxxxxxxx> <4D36B5EA.6040603@xxxxxxxxxxxxxxxxx>
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On 01/19/2011 04:59 AM, Stan Hoeppner wrote:
Then, logically, there is something different about this logical volume than the
others.  All of them reside atop the same volume group, atop the same two
physical RAID6 arrays, correct?  Since I'm not quite tired of playing dentist 

1. Were all of the LVs created with the same parameters?  If so, can you
demonstrate verification of this to us?
pvcreate --metadatacopies 2 /dev/cciss/c1d0p1
pvcreate --metadatacopies 2 /dev/cciss/c1d1p1
vgcreate vg0 /dev/cciss/c1d0p1 /dev/cciss/c1d1p1
lvcreate -n shared -L 2.1T /dev/vg0
lvcreate -n homes -L 810G /dev/vg0
2. Are all of them formatted with XFS?  Were all formatted with the same XFS
parameters?  If so, can you demonstrate verification of this to us?
mkfs.xfs -L homes -i attr=2,size=1024 -l version=2,size=128m,lazy-count=1 /dev/vg0/homes mkfs.xfs -L shared -i attr=2,size=1024 -l version=2,size=128m,lazy-count=1 /dev/vg0/shared
3. Are you encrypting, at some level, the one LV that is showing low 

Cory:  "The two arrays were added to a volume group and multiple logical volumes
were created."
No encryption
4. Was this volume group preexisting?  Are there other storage devices in this
volume group, or _only_ the RAID6 arrays?
Everything is new, hardware, LV's, file systems...
5. Have you attempted deleting and recreating the LV with the performance issue?
No and I don't have the room to recreate this LV
6. How many total logical volumes are in this volume group?
7. What Linux distribution are you using?  What kernel version?
SLES 10 SP2, i686

We are not magicians here Cory.  We need as much data from you as possible or we
can't help you.  I thought I made this clear earlier.  You need to gather as
much relevant data from that box as you can and present it here if you're
serious about solving this issue.

I get the feeling you just don't really care.  In which case, why did you even
ask for help in the first place?  Troubleshooting this issue requires your
_full_ participation and effort.

In these situations, it is most often the OP who solves his/her own issue, after
providing enough information here that we can point the OP in the right
direction.  The key here is "providing enough information".
Sorry I'm not trying to withhold information. Whatever you need to know just ask and I'll be happy to provide it.

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