- Community Home
- >
- Storage
- >
- Entry Storage Systems
- >
- Disk Enclosures
- >
- Re: linear vs. disbursed data layout
Disk Enclosures
1748289
Members
3192
Online
108761
Solutions
Forums
Categories
Company
Local Language
юдл
back
Forums
Discussions
Forums
- Data Protection and Retention
- Entry Storage Systems
- Legacy
- Midrange and Enterprise Storage
- Storage Networking
- HPE Nimble Storage
Discussions
Discussions
Discussions
Forums
Forums
Discussions
юдл
back
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
- BladeSystem Infrastructure and Application Solutions
- Appliance Servers
- Alpha Servers
- BackOffice Products
- Internet Products
- HPE 9000 and HPE e3000 Servers
- Networking
- Netservers
- Secure OS Software for Linux
- Server Management (Insight Manager 7)
- Windows Server 2003
- Operating System - Tru64 Unix
- ProLiant Deployment and Provisioning
- Linux-Based Community / Regional
- Microsoft System Center Integration
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Blogs
Information
Community
Resources
Community Language
Language
Forums
Blogs
Topic Options
- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО06-18-2002 10:28 AM
тАО06-18-2002 10:28 AM
linear vs. disbursed data layout
Hello, I'm new to a storage mgmt team and am hearing quite a debate regarding linear and disbursed ldev layout in an Hitachi 9960. Is there a good thorough explanation of what these are and any guidlines/suggestions of how to choose one over the other. I'm an HP sysadmin with experience with EMC.....thanks
ken
ken
2 REPLIES 2
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО06-18-2002 01:00 PM
тАО06-18-2002 01:00 PM
Re: linear vs. disbursed data layout
HP lays out XP's linear. It simplifies HP-UX System Administraton, and care and feeding of the array. It also makes it simple to determine where in the array any particular LDEV is, and makes upgrades more straightforward.
The difference is when LDEVs are allocated. Linear is analgous to disk concatenation (LDEVs sequential in numbering are located on the same array group or sequentially numbered groups), where disbursed is like striping. (The LDEVs are striped onto the array groups).
With Disbursed mode, you cannot predict with any certainty where an LDEV actually is in the array. It could be anywhere.
Worse, Hitachi's tools cannot tell you where it is - you have to access the SVP to find out where it is. (HP's Command View XP actually tells you which array group an LDEV is on). Of course, you're technically not allowed to access the SVP.
The reason that some at Hitachi like to disburse the LUNs is IFF you allocate your LUNs to hosts sequentially [ie: 0:00, 0:01, 0:02, etc], then you are guaranteed to be striping across the largest number of array groups possible.
This works until you add drives to the array... if you had 10 array groups, disbursed, and add another 5 array groups at a later date and continue your linear host allocation, the performance of the new drives will seem less because you're using fewer drives in the array.
We feel that this is better done manually, because you might want to separate your logs from your tablespaces - have them on different drive sets or in different sections of the array. If you disburse the LDEVs, you will make this nearly impossible.
We also make the correlation of CU to quadrant - ie: CU 0 is always the lower right quadrant of the array. DBA's like to know where their data is, so when they ask, you can point to the drives and say, "there!".
Either way, you have to do some tracking and manual operations - Disburse means that host assignments at initial installation are easier to manage, but later on becomes ugly, and Linear means taking the ugly up front so it will be cleaner for it's lifetime.
Good luck with the array... next time I hope you'll consider buying the HP version of the array - the XP512 or XP1024.
The difference is when LDEVs are allocated. Linear is analgous to disk concatenation (LDEVs sequential in numbering are located on the same array group or sequentially numbered groups), where disbursed is like striping. (The LDEVs are striped onto the array groups).
With Disbursed mode, you cannot predict with any certainty where an LDEV actually is in the array. It could be anywhere.
Worse, Hitachi's tools cannot tell you where it is - you have to access the SVP to find out where it is. (HP's Command View XP actually tells you which array group an LDEV is on). Of course, you're technically not allowed to access the SVP.
The reason that some at Hitachi like to disburse the LUNs is IFF you allocate your LUNs to hosts sequentially [ie: 0:00, 0:01, 0:02, etc], then you are guaranteed to be striping across the largest number of array groups possible.
This works until you add drives to the array... if you had 10 array groups, disbursed, and add another 5 array groups at a later date and continue your linear host allocation, the performance of the new drives will seem less because you're using fewer drives in the array.
We feel that this is better done manually, because you might want to separate your logs from your tablespaces - have them on different drive sets or in different sections of the array. If you disburse the LDEVs, you will make this nearly impossible.
We also make the correlation of CU to quadrant - ie: CU 0 is always the lower right quadrant of the array. DBA's like to know where their data is, so when they ask, you can point to the drives and say, "there!".
Either way, you have to do some tracking and manual operations - Disburse means that host assignments at initial installation are easier to manage, but later on becomes ugly, and Linear means taking the ugly up front so it will be cleaner for it's lifetime.
Good luck with the array... next time I hope you'll consider buying the HP version of the array - the XP512 or XP1024.
No matter where you go, there you are.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО06-19-2002 03:13 AM
тАО06-19-2002 03:13 AM
Re: linear vs. disbursed data layout
Leaner assigns the LDEV IDs in sequential order for all unassigned logical addresses within the parity group. This choice is appropriate for administartors who actively balance their disk array workload.
LVM striping among multiple gruops would be good example.
Disperse randomly rotates LDEV IDs among multiple groups across the disk array, elminating hot spots and improving data access.
This should be used by administrators that do not actively balance their disk array workload.
Hope this helps,
LVM striping among multiple gruops would be good example.
Disperse randomly rotates LDEV IDs among multiple groups across the disk array, elminating hot spots and improving data access.
This should be used by administrators that do not actively balance their disk array workload.
Hope this helps,
Never say "no" first.
The opinions expressed above are the personal opinions of the authors, not of Hewlett Packard Enterprise. By using this site, you accept the Terms of Use and Rules of Participation.
News and Events
Support
© Copyright 2024 Hewlett Packard Enterprise Development LP