Hidden SAN fragmentation

SQLServerCentral is supported by Red Gate Software Ltd.

Popular Topics

Home

Members

Calendar

Who's On

Home » Database Design » Hardware » Hidden SAN fragmentation

Hidden SAN fragmentation

Rate Topic

Display Mode

Topic Options

Author

Message

Evil Kraig F

Posted Thursday, January 13, 2011 1:00 PM

SSCertifiable

Group: General Forum Members
Last Login: Today @ 6:47 PM
Points: 5,678, Visits: 6,130

Hey folks, a quickie question about the drive space assignment mechanics.

We'll simplify things. Working on a single drive in a LUN, said drive is a 1Tera drive. I need 300 gigs, so I get a nice simple 300 gig LUN assignment off the single spindle, leaving 700 of it free.

I will eventually need all the space, but for now I drop 50 gigs into my LUN. The 700 gigs eventually gets assigned to something else, and it sporadically writes to the drive.

As I add files (or grow my .mdf), I use up more and more of my 300 gigs.

My 300 gigs looks contiguous from the perspective of the OS which can see into the LUN... however, is the physical spindle still contiguous, or does it interleave with the other 700 gigs assigned to a different LUN?

- Craig Farrell

Never stop learning, even if it hurts. Ego bruises are practically mandatory as you learn unless you've never risked enough to make a mistake.

For better assistance in answering your questions | Forum Netiquette
For index/tuning help, follow these directions. |Tally Tables
Twitter: @AnyWayDBA

Post #1047539

GSquared

Posted Thursday, January 13, 2011 1:42 PM

SSCoach

Group: General Forum Members
Last Login: 2 days ago @ 1:55 PM
Points: 15,442, Visits: 9,571

I'm pretty sure I've always seen them as single blocks of spaces on a drive, not fragmented all over. But that might be an artifact of how they're set up as opposed to a "natural law" kind of thing.

- Gus "GSquared", RSVP, OODA, MAP, NMVP, FAQ, SAT, SQL, DNA, RNA, UOI, IOU, AM, PM, AD, BC, BCE, USA, UN, CF, ROFL, LOL, ETC
Property of The Thread

"Nobody knows the age of the human race, but everyone agrees it's old enough to know better." - Anon

Post #1047557

alen teplitsky

Posted Monday, February 07, 2011 8:41 AM

Ten Centuries

Group: General Forum Members
Last Login: Yesterday @ 8:15 PM
Points: 1,409, Visits: 4,509

this will depend on the vendor. i believe with EMC you can assign specific drives as you want. Netapp everything is a RAID5 or 6 or something similar and you get chunks of disk space

https://plus.google.com/100125998302068852885/posts?hl=en
http://twitter.com/alent1234
x-box live gamertag: i am null
[url=http://live.xbox.com/en-US/MyXbox/Profile[/url]

Post #1059595

Nadrek

Posted Tuesday, February 08, 2011 8:28 AM

Say Hey Kid

Group: General Forum Members
Last Login: Monday, May 20, 2013 12:28 PM
Points: 675, Visits: 2,031

Ask your SAN expert about whether or not your LUN is assigned up front in a contiguous block, or as you write to it.

Post #1060292

« Prev Topic | Next Topic »

Permissions