- Community Home
- >
- Storage
- >
- Midrange and Enterprise Storage
- >
- HPE EVA Storage
- >
- EVA8100 +Solaris ZFS
HPE EVA Storage
1752676
Members
6145
Online
108789
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
Go to solution
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
тАО04-16-2009 06:09 AM
тАО04-16-2009 06:09 AM
We may be having potential performance problems due to ZFS Cache Flushes enabled on our array... Can someone shed some light?
Sun document on ZFS Cache Flushes and arrays with NVRAM:
http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide#Cache_Flushes
-Does the EVA we're attached to ignore flush requests?
"For many NVRAM-based storage arrays, a problem might come up if the array takes the cache flush request and actually does something rather than ignoring it. Some storage will flush their caches despite the fact that the NVRAM protection makes those caches as good as stable storage. "
-If we were to turn off ZFS's flush requests what happens to the array?
--Will the array automatically flush the cache?
--Can the cache be "filled up", if we don't request a flush from the system side?
Sun document on ZFS Cache Flushes and arrays with NVRAM:
http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide#Cache_Flushes
-Does the EVA we're attached to ignore flush requests?
"For many NVRAM-based storage arrays, a problem might come up if the array takes the cache flush request and actually does something rather than ignoring it. Some storage will flush their caches despite the fact that the NVRAM protection makes those caches as good as stable storage. "
-If we were to turn off ZFS's flush requests what happens to the array?
--Will the array automatically flush the cache?
--Can the cache be "filled up", if we don't request a flush from the system side?
Solved! Go to Solution.
2 REPLIES 2
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО04-16-2009 08:01 AM
тАО04-16-2009 08:01 AM
Solution
Brian,
It's interesting reading a document which still talks about NVRAM based storage systems. Currently, almost every mid-range to enterprise class storage systems offer cache RAM with battery backup which takes out the fear (of ZFS) to potentially loose the data in case of failure. On top of it, EVAs are designed with write-cache mirroring, hence it's very well protected against any such failures.
EVA write cache is flushed as soon as the drives are free, so if there is not much of activity in EVA will transfer the write-cache contents to drives immediately.
Not sure how the EVAs will behave to ZFS flush requests, your "the best" option is to turn off cache flush from ZFS.
It's interesting reading a document which still talks about NVRAM based storage systems. Currently, almost every mid-range to enterprise class storage systems offer cache RAM with battery backup which takes out the fear (of ZFS) to potentially loose the data in case of failure. On top of it, EVAs are designed with write-cache mirroring, hence it's very well protected against any such failures.
EVA write cache is flushed as soon as the drives are free, so if there is not much of activity in EVA will transfer the write-cache contents to drives immediately.
Not sure how the EVAs will behave to ZFS flush requests, your "the best" option is to turn off cache flush from ZFS.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО04-22-2009 11:10 AM
тАО04-22-2009 11:10 AM
Re: EVA8100 +Solaris ZFS
There is quite a bit of discussion on this topic, but non really dive deep into it. I am looking into converting some ufs san based filesystems to zfs san based filesystems and have observed poorer performance on the zfs san based filesystems. I have tested with disabling zfs flush request ( zfs_nocacheflush ) from the os, but as the evil guide stated, I shouldn't have to do this with 5.10 u5 and above. I am running 5.10 u6. I didn't see and difference with the setting zfs_nocacheflush. There is a way to disable the request form the array, but I am unable to test this for myself. If you are considering disabling the flush request from the os side, be sure you don't have any locally attached zfs pools.. as the flush will be turned off for them as well.
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