- Community Home
- >
- Storage
- >
- Midrange and Enterprise Storage
- >
- HPE 3PAR StoreServ Storage
- >
- How many disks can fail in 3PAR 7000 series?
Categories
Company
Local Language
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
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
Community
Resources
Forums
Blogs
- 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
тАО07-29-2013 08:13 AM
тАО07-29-2013 08:13 AM
Re: How many disks can fail in 3PAR 7000 series?
When writing, RAID-6 has a higher backend IO requirement (6 2/3 IOs) than RAID-5 (4 IOs).
RAID-5 has a 4 IO back end penalty. As a write comes in the old parity and old data must be read (two read IOs) then parity calculated and new parity and new data written out (two write IOs). So each random write to R5 has 4 back end IOs (2 read + 2 write).
RAID-6 calculation uses the XOR engine in the ASIC but must calculate two distinct parities (R5 only needs one parity) and need to compute parities over more data since RAID sets are larger.
Most writes require only two parities. However, a fraction (1/3 for step size 8), of the data blocks are used to compute 3 parities, so updating those blocks requires reading/updating 3 parities, hence the odd number 6 2/3 back end IOs for RAID-6.
Nevertheless, when using the large nearline (NL) drives, HP strongly recommends using RAID-6 and avoid RAID-5 due to the long rebuild time when and if a NL drive fails.
Note: While I work for HP, all of my comments (whether noted or not), are my own and are not any official representation of the company.
----------
If my post was useful, click on my KUDOS! "White Star" !
Note: While I am an HPE Employee, all of my comments (whether noted or not), are my own and are not any official representation of the company
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО08-09-2013 01:16 AM
тАО08-09-2013 01:16 AM
Re: How many disks can fail in 3PAR 7000 series?
Hi,
For HP 3PAR storage system querries you can also visit the HP Guided troubleshooting tree.
Below is the link for 3PAR HPGT:
HP Guided Troubleshooting Solving issues
PS
To assign points on this post? Click the white Thumbs up below!
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО08-09-2013 07:20 PM
тАО08-09-2013 07:20 PM
Re: How many disks can fail in 3PAR 7000 series?
Hi HP Pro
if raid 5 (3+1) CPG with 16 disks in same drive enclosure still can fail 1 disk
and if I choose raid 5 (7+1) CPG with 16 disks in same enclosure still can fail 1 disk
my better choice is raid 5 (7+1) because it can be usable capacity more than raid 5 (3+1)
I'm still not fully understand about How many disks can fail in 3PAR 7000 series?
appreciated for clarify
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО08-09-2013 10:04 PM - edited тАО08-09-2013 10:12 PM
тАО08-09-2013 10:04 PM - edited тАО08-09-2013 10:12 PM
Re: How many disks can fail in 3PAR 7000 series?
>If raid 5 (3+1) CPG can fail 1 disk
>if raid 5 (7+1) CPG can fail 1 disk
Yes.
>my better choice is raid 5 (7+1) because it can be usable capacity more than raid 5 (3+1)
Yes. But if one disk fails, you now have to read 7 disks to recompute the data.
>I'm still not fully understand about How many disks can fail in 3PAR 7000 series?
Nothing has changed. For RAID 1 and 5, just one disk, at the same time. For RAID 6, just two, at the same time.
If there is a delay, the data can be copied to spare chunklets.
What are you trying to do/learn with this info?
- « Previous
-
- 1
- 2
- Next »