I was wondering experts over here could answer few of my questions.
1) Is there a way on a PS6000E to find out how many Raid 5 sets are created with RAID 50 (need this value for write penalty)
2) Any performance implications when RAID 50 (SATA 7.2K Drives) + RAID 10 (SAS 15K) are present in a same pool.
3) Any recommendations on iSCSI setup for XenServer with Dell EqualLogic.
Any input is appreciated.
Re: 2. That really depends on the version of FW. For best results, you should be at 5.2.2. That will deal better with the disparate RAID types. Using SANHQ to monitor the group is highly recommended. That will help you determine if splitting into two pools would be better. Then you have such different RPM speeds, generally, separate pools is better. You lose some of the benefit of 15K drives since data is striped across the members and the slower drives tend to be larger which tends to mean they get a higher percentage of IO load. Again 5.2.2 will help mitigate this but my personal preference would be to split them.
Re: 3. Citrix has three options there. Storage Repository Adapter, LVM over iSCSI and Storage Link. The last one only works with 6.0 and carries and additional cost I believe. The first one, allows you to allocate space and carve it up via their GUI for each VM. It will also take EQL snapshots as well. It creates very unique volume names and descriptions, NEVER manually modify either. Otherwise you can bring the environment to a halt. Make sure you have the latest version is you go that route. LVM over iSCSI doesn't give you the snapshot creation option. I have not tried the Storage Link product as of yet. So I can't offer any advise there. Last I knew, there was still no MPIO support from their GUI. At least for SRA or LVM over iSCSI. Just teaming.
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A PS6000 uses 2 7-drive raid 5's when running raid 50.
Member since 2003
Thanks Dev Mgr for the quick response,
How about PS6100 with 24drives? any clue for the other 2 question?
I have the impression that those run 3 raid 5's judging from the available space. They still have 2 hotspares, so it must run 2 x 7 drives and 1 x 8 drives, or something like that.
You are most welcome!
I forget to mention on Storage Repository you can also clone VMs very quickly. It actually clones the volume on the array side so it's near instantaneous.
Just wanted to chime in and let you guys know that currently (June 2012), xencenter does not support firmware 5.2.X (on any version of xen). I'm having serious issues adding additional storage to an existing pool that has already been upgraded to 5.2.2.
I don't doubt that you have an issue, but I strongly suspect it's not due to 5.2.2. 5.1.x and 5.2.x are functionally the same. 5.2.x has support for new controller HW and bug fixes. The iSCSI part is unchanged.
according to citrix support, there have been certain API changes in firmware 5.2.X that render storagelink not usable until xencenter can be updated to utilize new the commands - do you know this to not be the case?
The storage adapter doesn't use an API it uses the array CLI. There are some new commands but old ones are still there. However, if they are not going to support it, then it's moot. It will exclude customers from using the most current and future HW, features and access to fixes.
I'm not all that familiar with Xen, but can you not just create a volume in groupmanager, set the ACLs up correctly and then have Xen 'rescan' to find the new storage so it can format it and use it?
The VMware Host Integration Toolkit from Equallogic seems to offer similar features to the Citrix plug-in, but you can still add storage 'the old fashion way'.
Xen's storage adapter is a very different animal. You can use "LVM over iSCSI" with Xen, which would do what you expect. However, the storage adapter reads the group info, then creates volumes for VMs on the fly. Brings that volume online when you start a VM, and offline when you shutdown. It also allows you to clone a VM/VOL or create an EQL HW snapshot from within their GUI. So it does offer some very nice integration features. It uses CLI commands to accomplish this.