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List:       evms-devel
Subject:    Re: [Evms-devel] Some more problems
From:       Kevin Corry <kevcorry () us ! ibm ! com>
Date:       2004-10-14 16:59:07
Message-ID: 200410141159.07517.kevcorry () us ! ibm ! com
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On Thursday 14 October 2004 12:20 am, Vijay Kumar Agrawal, Noida wrote:
> Hi all !!!
> There are some more questions in my mind regarding EVMS.
>
> 1. Does EVMS support  the feature "Hot spot Management"(The management like
> mirroring policy of the most frequently used storage spaces.)?

No. The linux MD driver only supports normal mirroring (RAID-1). I don't know 
of any linux driver or tool that provides this capability.

> 2.  Does it support Online Movement of a logical volume from one physical
> volume to another?

I addressed this in an email from yesterday:

---
Yes, there are a number of ways you can "move" data around. If you're using 
LVM containers and regions, you can move all data from one PV to another PV, 
or move individual physical-extents around within the container. If you're 
using DOS segments, you can move the segment to an unused freespace portion 
of the same disk. If you're using drive-linking or software-raid, you can 
replace child objects with other child objects. Most of these can be done 
online.
---

If you would like additional details about any of these, please see the 
following sections of the EVMS User-Guide.
http://evms.sourceforge.net/user_guide/#evmsreplaceobjects
http://evms.sourceforge.net/user_guide/#segstorobjs
http://evms.sourceforge.net/user_guide/#appxlvm

> 3. Does EVMS provide Dynamic Multipath support (DMP is a method of
> providing two or more hardware paths to a single drive. For example, the
> physical hardware can have at least two paths directing I/O to the same
> drive. Volume Manager arbitrarily selects one of the paths and creates a
> single device entry, then transfers data across both paths to spread the
> I/O.)?
> -------i think that it supports DMP with the device Mapper.

EVMS does have some simple multipath support that is part of the MD plugin. 
However, the future of multipath support in Linux will be with the 
multipath-tools project, which you can find at:
http://christophe.varoqui.free.fr/multipath.html

Multipath devices created by these tools will be recognized like normal disks 
by EVMS.

> 4.Does EVMS provide Performance monitoring and tuning tools (I/O statistics
> tool, recovery speed monitoring etc.) support ?

EVMS doesn't provide any performance monitoring of its own, but there are 
performance monitoring tools available for Linux that can monitor I/O 
statistics. Some potentially useful URLs:
http://www.die.net/doc/linux/man/man1/sar.1.html
http://www.die.net/doc/linux/man/man1/iostat.1.html

There are probably more comprehensive tools available as well.

> 5.Does EVMS provide any backup file for storing the Metadata of volume
> created so that user would be able to restore the state?

This feature is scheduled for EVMS 2.5.

> 6.Does EVMS provide the centralized Management feature (Centralized storage
> management provides a domain wide view of disk storage resources.) ?

A feature similar to what you've described is available if you're running a 
Linux-HA cluster. You can use the EVMS UI to manage the volumes on any node 
in the Linux-HA cluster.

-- 
Kevin Corry
kevcorry@us.ibm.com
http://evms.sourceforge.net/


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