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Re: extremely slow write performance plaintext

To: xfs@xxxxxxxxxxx
Subject: Re: extremely slow write performance plaintext
From: Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx>
Date: Wed, 19 Jan 2011 03:59:06 -0600
In-reply-to: <1779_1295360207_4D35A0CF_1779_747_1_4D35A0CF.9050503@xxxxxxxxxxxxxxx>
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>
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Cory Coager put forth on 1/18/2011 8:16 AM:

> No, it has never worked properly.  Also, I want to stress that I am only 
> having
> performance issues with one logical volume, the others seem fine.

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?

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?

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."

4. Was this volume group preexisting?  Are there other storage devices in this
volume group, or _only_ the RAID6 arrays?

5. Have you attempted deleting and recreating the LV with the performance issue?

6. How many total logical volumes are in this volume group?

7. What Linux distribution are you using?  What kernel version?

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".


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