Unsolved
This post is more than 5 years old
14 Posts
0
765
Defrag of CX4 Storage Pools
Hi,
I would like some opinions and I suppose have a question(s) around defrag of a Storage Pool which I assume will be a background task along with available capacity within a Storage Pool. What impact would higher Pool capacity utilization have on defrag operation within a Pool? Will it be more SP intensive since it does read/writes in a more restricted space within the Pool? Does defrag utilize any SP cache for its operation?
I'm talking way pass the EMC preset (recommended?) Pool utilization threshold of 70%, more mid 90%.
Thank you
kelleg
4.5K Posts
1
October 18th, 2013 09:00
On the CX4 and VNX, you can not defrag a Pool, only raid group.
The performance impact on the LUNs in a raid group will depend on a number of factors: defrag rate, what the LUNs are being used for (usage), the Utilization of the LUNs by the hosts and the expectation of performance for those LUNs, the type and speed of the disks in the raid group, the size of the raid group, etc.
glen
nodrogs
14 Posts
0
October 20th, 2013 06:00
As defrags on a RAID Group is user initiated (low, med. etc.) and not an option on Pools does this means that there are no defrag maintenance on Pools as a background task handled within the array?
Anonymous
5 Practitioner
5 Practitioner
•
274.2K Posts
1
October 20th, 2013 13:00
In raid groups it's more like partition tables and has limited space to hold up lun mappings to raid group physical addresses which LUN resides.
LUN can reside in contiguous space in a RAID group but not in Pools. LUNs are written to Pool as chunks of data so a large mapping bitmap is held for thin/thick LUNs on a particular pool. When a LUN is deleted from pool, bitmap is cleared so that means spaces that LUN uses freed up immediately, so new chunks of data from other LUN can be written.
br,
Cenk
nodrogs
14 Posts
0
October 20th, 2013 16:00
Thank you gentleman, great explanations.
kelleg
4.5K Posts
0
October 21st, 2013 14:00
Don't forget to mark your question "Answered" and award points to the person with the best answer.
glen