Comments on: To extend or not to extend? That is the question. http://professionalvmware.com/2009/01/to-extend-or-not-to-extend-that-is-the-question/ How Many Turtles Can You Fit On A Rock? Tue, 22 May 2012 08:48:04 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: VMware vSphere: Aumentando la capacidad de un Datastore | Tecnologias Aplicadashttp://professionalvmware.com/2009/01/to-extend-or-not-to-extend-that-is-the-question/comment-page-1/#comment-2254 VMware vSphere: Aumentando la capacidad de un Datastore | Tecnologias Aplicadas Sun, 19 Feb 2012 06:12:19 +0000 http://professionalvmware.com/?p=405#comment-2254 [...] En el siguiente link hay un interesante articulo que discute sobre Expandir o Extender un Datastore para aumentar la capacidad de este:http://professionalvmware.com/2009/01/to-extend-or-not-to-extend-that-is-the-question/ [...] [...] En el siguiente link hay un interesante articulo que discute sobre Expandir o Extender un Datastore para aumentar la capacidad de este:http://professionalvmware.com/2009/01/to-extend-or-not-to-extend-that-is-the-question/ [...]

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]]> By: songshttp://professionalvmware.com/2009/01/to-extend-or-not-to-extend-that-is-the-question/comment-page-1/#comment-870 songs Thu, 17 Sep 2009 13:45:54 +0000 http://professionalvmware.com/?p=405#comment-870 This is a nice post. It give me an idea to choose what will be the right choice. This is a nice post. It give me an idea to choose what will be the right choice.

]]> By: songshttp://professionalvmware.com/2009/01/to-extend-or-not-to-extend-that-is-the-question/comment-page-1/#comment-637 songs Thu, 17 Sep 2009 08:45:54 +0000 http://professionalvmware.com/?p=405#comment-637 This is a nice post. It give me an idea to choose what will be the right choice. This is a nice post. It give me an idea to choose what will be the right choice.

]]> By: Resumehttp://professionalvmware.com/2009/01/to-extend-or-not-to-extend-that-is-the-question/comment-page-1/#comment-613 Resume Wed, 09 Sep 2009 08:53:21 +0000 http://professionalvmware.com/?p=405#comment-613 test test

]]> By: darkyhttp://professionalvmware.com/2009/01/to-extend-or-not-to-extend-that-is-the-question/comment-page-1/#comment-122 darky Mon, 19 Jan 2009 22:48:29 +0000 http://professionalvmware.com/?p=405#comment-122 To answer you first question, I do not have ADHD meds. To answer your second and third question, we are talking about extents. The reason snapshots were mentioned is due to the fact that they are the primary reason a datastore runs out of space unexpectedly which requires the volume to be extended or snapshots to be commited in order to free up enough space for you to power on the VM. I left that more or less as implied as this article was written for people that may have already run into this issue before and would recognize the immediate connection between the two.<br><br>If your extents are on the same physical LUN then this article does not apply to you because there is no dependency. I thought this was clearly stated in the 2nd paragraph. While we are on the subject though, I should mention that while extents on the same LUN do not have dependency issues, that LUN can only be expanded 3 times as you are only allow 4 primary partitions per LUN. In addition to this, if the partition table for that LUN was ever wiped out (many ways this can happen), it is an extremely messy operation to recalculate the original partition boundaries. Other than those two points, using extents on the same LUN is fine.<br><br>There was really only one main reason not to use extents in this article and that is pure the dependecy factor it has with another LUN. From that one caveat alone spawns a whole series of issues. There are plenty of reasons and benefits to using extents however this one downside far outweighs and positive result that long term extent usage will get you.<br><br>I hope this clears things up for you. To answer you first question, I do not have ADHD meds. To answer your second and third question, we are talking about extents. The reason snapshots were mentioned is due to the fact that they are the primary reason a datastore runs out of space unexpectedly which requires the volume to be extended or snapshots to be commited in order to free up enough space for you to power on the VM. I left that more or less as implied as this article was written for people that may have already run into this issue before and would recognize the immediate connection between the two.

If your extents are on the same physical LUN then this article does not apply to you because there is no dependency. I thought this was clearly stated in the 2nd paragraph. While we are on the subject though, I should mention that while extents on the same LUN do not have dependency issues, that LUN can only be expanded 3 times as you are only allow 4 primary partitions per LUN. In addition to this, if the partition table for that LUN was ever wiped out (many ways this can happen), it is an extremely messy operation to recalculate the original partition boundaries. Other than those two points, using extents on the same LUN is fine.

There was really only one main reason not to use extents in this article and that is pure the dependecy factor it has with another LUN. From that one caveat alone spawns a whole series of issues. There are plenty of reasons and benefits to using extents however this one downside far outweighs and positive result that long term extent usage will get you.

I hope this clears things up for you.

]]> By: darkyhttp://professionalvmware.com/2009/01/to-extend-or-not-to-extend-that-is-the-question/comment-page-1/#comment-121 darky Mon, 19 Jan 2009 22:38:20 +0000 http://professionalvmware.com/?p=405#comment-121 I am pleased to see you mention lock contention as it isn't something I brought up in the post. The reason I didn't mention it was because such a design only benefits Hitachi based arrays (HDS and HP XP series) since they are slow to lock and unlock SCSI-2 based SCSI reservations. I am pleased to see you mention lock contention as it isn't something I brought up in the post. The reason I didn't mention it was because such a design only benefits Hitachi based arrays (HDS and HP XP series) since they are slow to lock and unlock SCSI-2 based SCSI reservations.

]]> By: cwhttp://professionalvmware.com/2009/01/to-extend-or-not-to-extend-that-is-the-question/comment-page-1/#comment-120 cw Mon, 19 Jan 2009 22:25:17 +0000 http://professionalvmware.com/?p=405#comment-120 don't mean to be a hater, but:<br>did you forget to take you ADHD meds before writing that? are we talking about extents or snapshots? how do they relate here?<br><br>what are these "bad events" that might destroy a LUN?<br><br>if both extents are on the same expanded LUN, then there is no LUN dependency so what are you going on about? Are you OK with this situation? it's not clear from your article.<br><br>I'm not trying to defend extents, but this article doens't really seems to cover any reasons NOT to use them, except that doing so earns your disapproval and since you aren't my boss, nor a potential boss (as fas as I can tell) then why I care?. Personally, I'm against them too, and I read the article to see if your reasons match up with mine, either to validate my own reasons or to re-evaluate them. But all i got from this was confusion. don't mean to be a hater, but:
did you forget to take you ADHD meds before writing that? are we talking about extents or snapshots? how do they relate here?

what are these “bad events” that might destroy a LUN?

if both extents are on the same expanded LUN, then there is no LUN dependency so what are you going on about? Are you OK with this situation? it's not clear from your article.

I'm not trying to defend extents, but this article doens't really seems to cover any reasons NOT to use them, except that doing so earns your disapproval and since you aren't my boss, nor a potential boss (as fas as I can tell) then why I care?. Personally, I'm against them too, and I read the article to see if your reasons match up with mine, either to validate my own reasons or to re-evaluate them. But all i got from this was confusion.

]]> By: Russellhttp://professionalvmware.com/2009/01/to-extend-or-not-to-extend-that-is-the-question/comment-page-1/#comment-119 Russell Mon, 19 Jan 2009 22:17:09 +0000 http://professionalvmware.com/?p=405#comment-119 Another thing to consider, is that using extents will essentially contradict the practice of avoiding lock contention by using smaller datastores and housing less VMs. All in all I have never seen them to be worth it in my experience. <br><br>If you're storing more than 12-14 or so VMs on a single LUN you're probably already negatively impacting performance anyway. Extents won't help this by any means. <br><br>I agree, consider them an "oh shit" button when you run out of space but migrate away from them ASAP. Another thing to consider, is that using extents will essentially contradict the practice of avoiding lock contention by using smaller datastores and housing less VMs. All in all I have never seen them to be worth it in my experience.

If you're storing more than 12-14 or so VMs on a single LUN you're probably already negatively impacting performance anyway. Extents won't help this by any means.

I agree, consider them an “oh shit” button when you run out of space but migrate away from them ASAP.

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