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21 Comments
- pseudojd, on 04/27/2008, -0/+15Is that really ridiculously good or really ridiculously bad?
- mmcgrath, on 04/27/2008, -0/+10We've been using iscsi with with xen for about a year and a half for Fedora's infrastructure. For our vm's its been great, we're in the perfect situation for it. Most of our data io is done by database calls. Our target is a netapp and the performance, for the most part has been great.... as long as the machines don't start swapping. Though at that point they behave not that much differently from the other non iscsi boxes we have as long as they're not all swapping at the same time.... though I suppose thats like any shared storage.
The biggest drawback I've seen with iscsi is one of our database servers uses it for its primary storage (we thought we'd try it out). We've got logs and swap on local storage and the main storage is on iscsi. The problem is the fine tuning is different. Buffering behaves a bit different. And I can't decide between noop or cfq for the default scheduler.
Needless to say though, having all the vm's on iscsi is extremely handy. A whole box could catch on fire and all I have to do is get on to another box and xm start it. When scripted it's just like the box rebooted itself. - inactive, on 04/27/2008, -1/+5no ***** - 4 gb fibre is my little buddy
- riz94107, on 04/27/2008, -2/+6Must be a slow night - I like iSCSI and all, but this was one lame-ass "article".
- inactive, on 04/27/2008, -0/+3iSCSI runs fine, great if not perfect for 1 location.
HOWEVER, we keep the EDB files for exchange on a non-iSCSI SAN for replication purposes. There is simply too much latency through iSCSI in comparison. (in love with riverbed's replication features BTW)
But that doesnt mean we dont use iSCSI for gods sake. Of course we use the best priced option for its features. It would be stupid not to! - specialK16, on 04/27/2008, -0/+3I've always wondered. We have Gigabit ethernet now, yes... but is SAN still effective in WAN enviroments? Wouldn't the lag be a bottleneck?
- lateralus, on 04/27/2008, -0/+3Then should that be 10GiB iSCSI > 4GB Fibre?
- longbow486, on 04/27/2008, -1/+3I am currently running three Lefthand Networks SAN's for Oracle, VMware, and File storage at work. Each ESX server is a Dual Opteron Dual core 2.8Ghz with 32GB of RAM and has two bonded Gibit connections for iSCSI, and a RHEL 4.6 VM boots in no more then 1 min, Server 2003 boots in the same amount of time.
- gazzerh, on 04/27/2008, -0/+210GiB iSCSI < 4gb fibre. Grow up. Fibre has had it's day and it's days are numbered. I would start migrating!!
- jdfalk, on 04/27/2008, -1/+3One of my favorite comments on Dig is the guy who says "Well I have never seen any one do it so no one does!" So using that logic every place I have worked at virtualizes their server farms so EVERYONE must be virtualizing everything. Idiot. I wish I could dig you down twice.
See: http://code.google.com/p/ganeti/ I think that's one large customer using virtualization to better utilize their massive server farms. IBM mainframes have been doing virtualization for years, and Microsoft itself has responded to the virtualization craze by fully integrating virtualization with their next version of windows server hence WINDOWS SERVER 2008 WITH HYPER-V. Now for more case studies: https://www.microsoft.com/virtualization/casestudy ...
Dear God when will stupid die from Dig..... - taphagreg, on 04/29/2008, -0/+2Actually, I am always surprised by how expensive FC is. The technology has been around for five years and still isn't cheap. Why is that ?
Wouldn't be because the vendors are sticking it to you would it ?
Or maybe the technology has not been adopted by enough people to make manufacturing it viable ?
Or possibly, FC is just not a successful technology.
I am still not sure what is the reason. - Zylog, on 04/27/2008, -2/+3iSCSI is buggy on me
- GarrettB, on 04/27/2008, -5/+6Am I the only person going "What THE *****"?
- taphagreg, on 04/29/2008, -0/+1Yes, using SAN across the WAN isn't a good idea. So you design your network so that there is no lag. Lots of similarities between VoIP networks and Storage networks, well, except for the fact that your your latency should be
- specialK16, on 04/27/2008, -0/+1I ask again. Latency?
- tmpoirier, on 04/27/2008, -0/+1that's what i was going to ask.
- Lucas123, on 04/27/2008, -1/+1iSCSI is great for consolidating storage needs for large Wintel server farms, but I don't think it will be used any time soon as primary storage network in enterprise-class companies. Fibre Channel over Ethernet is an up and coming protocol that offers the best alternative to rolling out expensive Fibre Channel networks, and allowing you to use Ethernet switches and network interface cards to create a storage network.
- Falldog, on 04/27/2008, -2/+2I disagree. Fibre is still a lot easier to manage and deploy vs. iSCSI even if it is slightly cheaper to avoid buying fiber switches and laying new cables. A well designed VM server will not encounter any noticeable performance change between Fibre and iSCSI. There are still extra layers of overhead and whether the hosted OS thinks it is talking to a physically attached hard drive or over a network port make little difference.
Regardless, the author mentions that mission critical servers as his case. True mission critical servers would not run on VM hosts (I have yet to see a customer run production Exchange on VM) nor would they be talking to storage so far away that iSCSI's distance advantage (over Fibre) would come into play.
Of course, not to mention the obvious throughput benefit of fiber over Cat 6. - TheEsp, on 04/28/2008, -1/+1"In conclusion, with the emergence of relatively inexpensive 10 gigE switch and HBA Solutions, continued sophistication of operating systems and applications, the time is right to start adopting iSCSI for your mission critical storage networking needs"
So all those networking guys you now have to not only worry about IP your going to get the storage basket as well. I always find it amusing that these people who say "oohh ISCSI is so much cheaper than Fibre Channel"
Checked out the prices latley for Fibre kit you'll be quite suprise how cheap HBA's and switches are now. - perrinwolf, on 04/27/2008, -2/+0One thing I have learning in over 10+ years of working in IT- "never say never" and "just because you haven't seen it doesn't mean its not being successfully used". I personally know of several large companies and universities running mission critical servers on VMs (VMware ESX), they are running large Exchange servers, SQL 2005, SharePoint/MOSS 2007 and web server farms.
- mastication, on 04/27/2008, -6/+2iSCSI© - Copyright Apple, 2008.
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