Combining server virtualization and Internet SCSI (iSCSI) storage creates many benefits with a very flexible platform that is easily set up and expanded as needed. This chat focuses on using iSCSI with virtualization and the ways that it is beneficial.

Technical Community - Background Reading

Chat Transcript

DELL-ToddM Hello Adam
Adam_McCurdy Howdy. I'm actually a Dell Employee over in PowerConnect support. I was just told about this chat by Jason Groce, one of our training developers. Figured I'd check it out and see if anything was happening.
DELL-ToddM Cool. We welcome all. I am expecting a couple of more Dell iSCSI guys to show up as well.
Adam_McCurdy A bit. We've got a few switches that are "iSCSI optimized." The 54xx series
DELL-ToddM We got a few of the iSCSI-optimized switches in our lab for our iSCSI network as well. Waiting for people to join the chat
DELL-ToddM Hello Scott
DELL-ScottH Hey Todd, had a meeting just before this... Hey Adam!
DELL-ToddM I was beginning to think that you were caught in a TF2 session
DELL-ScottH Man down, man down! Medic!
DELL-ToddM Adam works in PowerConnect support. Adam, where are you located? I am in RR5
DELL-ScottH Cool, I'm thinking about duct taping 10 Gb links together to get 10 Gb, will that work :-)
DELL-ScottH Hey Greg
DELL-ToddM Hey Greg! Hows it going?
ramseyg_dell Hello. Pretty good. Keeping busy. . .I mean normal
DELL-ScottH Working half days again? Twelve hours
ramseyg_dell Exactly... :)
DELL-ToddM Well, we might be a little light on attendance today, with July 4th coming up
DELL-ScottH No pain, no gain!
DELL-ToddM Hey Marc, glad to see you!
DELL-ScottH Yeah, just looks like a bunch of Dell dorks
Dell-Marc Nice to be here
DELL-ScottH Marc being the biggest! No wait, I'm the biggest
Dell-Marc Dorkydorkydorky doo
DELL-ScottH And scrappy doodle doooooooo
Dell-Marc Ive been gone a couple; how's it been?
DELL-ToddM Scott and I were both on vacation last week as well. So it has been the typical digging out my in-box the last day or so. Following up on last week's FlexAddress chat, there was an article on The Register that is pretty good: www.theregister.co.uk/2008/07/01/dell_flex_address_blade/
DELL-ToddM That is, if you are into blades and cool whiz-bang technology. Today we are scheduled to discuss the benefits of iSCSI for virtualization. However, we can discuss anything we want, especially if no customers are going to show up
DELL-ToddM I ran across an interesting blog post on virtual geek that had some good iSCSI information included and even mentioned Marc's favorite topic—FCoE:
http://virtualgeek.typepad.com/virtual_geek/2008/06/answers-to-a-bu.html
DELL-ScottH Marc, what's the market penetration for iSCSI versus Fibre? Something I'm curious about. Nice link, Todd, looks like a good read
DELL-ToddM Marc, I suspect that Java has caused you problems again
DELL-ScottH I don't think Marc fixed his Java problems
Marc-Dell Sorry guys, I got bounced out; my Java client almost always freezes my system, then it's a power off sort of thing
Marc-Dell Yep. What's a muthuh to do?
DELL-ScottH That stinks...at least it's a "YP" and not an "MP": Your problem, not my problem
DELL-ToddM While you were out I included a link to a blog post on Virtual Geek: http://virtualgeek.typepad.com/virtual_geek/2008/06/answers-to-a-bu.html
Marc-Dell Thanks for the elucidation
DELL-ToddM Has some iSCSI data and talks about the FCoE issue a bit. He is on your side; although he appears to be an EMC guy
DELL-ScottH Marc, I was asking you what percentage of enterprise storage is iSCSI versus Fibre in the market right now?
Marc-Dell What's their opinion?
DELL-ScottH Just curious
Marc-Dell Most of it's Fibre. Probably over 90 percent installed SAN storage. I don't keep up real well with the numbers
DELL-ScottH But that's just a time thing, right...like LPs before CCs?
DELL-ToddM Virtual Geek is very pro iSCSI; I couldn't figure out who he is (who he works for or whatever)
Marc-Dell But the growth in iSCSI is in the 70–80 percent range, whereas FC growth is single digits. You know the whole FCoE thing is interesting. It will make a difference. I'm not a fan, but I think Dell or any other vendor is crazy not to have products
DELL-ToddM I agree that you have to have FCoE because some Fibre customers will want to go that way
Marc-Dell The last company to shut down FC was Adaptec, and look where it got them. Yes, there are certainly customers that have storage needs that are larger than what iSCSI can handle
DELL-ToddM It reminds me of the early days of x86 servers. There were lots of customers that still needed big iron
Marc-Dell In what way? Oh yeah
DELL-ToddM But that has continued to decrease as x86 has matured and improved. I suspect that iscsi will have the same type of adoption. Everybody will do it to a certain extent, and it will grow over time
DELL-ScottH Hey Chad!
DELL-ToddM Hello Chad
Marc-Dell Theres so much Fud about iSCSI, but it will probably never replace FC completely
DELL-ScottH Reminder to everyone. You can click Action, Recent Room History to catch up on the conversation
chad Thanks
DELL-ToddM Is this the Dell Chad that knows everything about blades? Or another Chad?
chad i would say another Chad...
Marc-Dell What do you want to find out or talk about?
DELL-ToddM We have been discussing iSCSI and Fibre Channel in general terms, but are open to anything
chad Just poking in the chat to see what it was about really. Did a small iSCSI implementation a while back. Really liked it but FC still seems to rule mainstream
Marc-Dell BTW, you guys see the FlexAddress announcement today?
Marc-Dell What's your environment like? So I'd agree for the most part. I'm a big iSCSI bigot, but FC does rule the mainstream still today
Marc-Dell There is some very cool stuff in iSCSI that got the advantage of hindsight—coming as it did after FC was already out
DELL-ScottH Hi Brian
DELL-ToddM Hello Brian
Marc-Dell Of course, not everybody implements it
Brian Hello
chad Large...mainly DX and Clarion based
DELL-ToddM I think that a big advantage with iSCSI is that you don't have to do zoning. Makes admin and setup easier
chad iscsi was more of a test the technology for a lower cost storage solution. that could afford to be slightly slower disks.
Marc-Dell FC really blew network routing and virtualization, but that stuff has been more or less repaired. A lot of people mistake bandwidth for transmission speed and latency. Hey, think just because iSCSI runs at a Gb/sec that it's slower than 4 Gb FC—but that's not true—the main difference is how much stuff is in the pipe
DELL-ScottH Yeah, driving my Yugo down an eight-lane highway gets me to the store just as fast as when I drive down the two-lane road
Marc-Dell iSCSI subsystems with 15,000 rpm SAS drives are extremely fast
DELL-ToddM Small block random I/O should perform about the same as long as the disks are the same rpms
Marc-Dell Yes
Marc-Dell So one of the problems iSCSI has had is that some of the vendors just ported their FC controller code to iSCSI and didn't optimize it in any way
DELL-ToddM I could guess which vendor you are talking about...but I won't
Marc-Dell Actually, there are several; there's a function in iSCSI called iSCSI redirect that allows an I/O to be re-routed through another port if that would be preferable. So it's possible to load balance traffic through multiple ports that way with far better granularity than what you typically get with multipathing software that has "large chuck" granularity. Of course, the Dell EqualLogic iSCSI products use it, which is one of the reasons I/O performance is so good with these systems
DELL-ToddM Brian, you joined a few minutes ago; anything specific you wanted to talk about? General topic is iSCSI
DELL-ToddM Hey Jeff!
Jeff_Glenn Did I miss anything exciting?
Marc-Dell A few typos; more than a few
DELL-ToddM Of course, Action, Recent Room History will fill you in on the details
Jeff_Glenn Thanks!
DELL-ToddM Welcome Kristoffer. Good to see you
Brian I've been running iSCSI on our ESX clusters since 3.0 now and am real close to migrating to NFS and was interested in any benefits of iSCSI I might be missing before I threw the switch
Kristoffer Hi guys :)
DELL-ScottH Hey Kristoffer! And Jeff!
Marc-Dell I think the benefits have more to do with product implementations than with the protocols used
Brian We use NetApp filers and have FC, iSCSI and NFS available to us
DELL-ToddM Hey Robby!
Brian The FC never made much sense from a cost perspective for the loads we are running
Marc-Dell In that case, I'd use NFS too. Their iSCSI implementation is pretty slow
Brian I bought into the iSCSI is better than NFS stuff from VMware. We just finished some benchmarking that puts NFS at about 25 percent faster than iSCSI
Marc-Dell Yeah, but NetApp runs their iSCSI through their native file system; I'm not sure how the mapping works, but it maps a volume space over the file space so they can get the same snapshot function. It gives operating compatibility, but the performance overhead for NetApp's iSCSI is pretty high
Brian I really like the idea of getting away from LUN management and getting thin-provisioning by default as well. That's definitely what we have seen
Marc-Dell Like I said, if I was using NetApp filers, I'd go NFS too. But here are much better iSCSI implementations, but I don't necessarily want to go into selling mode here. What are your scaling needs?
Brian We are mostly working with lots of small data centers. About four ESX hosts and 50 VMs each. We already have all the NetApp storage in place so adding a shelf where needed was easier than adding new heads
Marc-Dell Is this a hosting business?
Brian Software development company
Marc-Dell Okay. Overall, how is NetApp doing for you?
Brian Pretty good for its intended uses. It was originally NAS only, and it's great for that
Marc-Dell If you are already running VMware machines through the NetApp filers now, I think you'll be okay once you get everything ported over to NFS. Do you have any 10 Gb connections?
Brian Just starting that migration process
Marc-Dell I have no idea what the resulting NFS processing overhead would be for VMware systems with lots of small guests. Probably okay if they don't use the network too much
DELL-ToddM Kristoffer, I know that you are using blades for a hosting environment. Are you using iSCSI storage or just local disks?
Marc-Dell But, if network utilization climbs, then NFS could have some disadvantages at 10 Gb; but that depends on net utilization
Kristoffer I'm using iSCSI, just installed a PowerVault MD3000i, and have a a X4 waiting...
Brian We'd looked at the PowerVault MD3000i for some smaller sites without NetApp filers already in place
Kristoffer It's going to be so exciting...
Brian How's it doing?
Kristoffer Right now it performs really well with the 15,000 rpm disks...but the SATA disks have some kind of problem
Brian Was that 15 disks without additional shelves?
Kristoffer On a two-SAS disk RAID-1 I get 100+ MB/sec.; on a two-SATA disk RAOID-1 I get 15 MB/sec. :(
Kristoffer Yes, without shelves... I'm currently gathering data on the issue for my Dell tech friends
Marc-Dell Go Todd
DELL-ToddM I can get the PowerVault MD guys to take a look. I haven't heard of the issue before. We only have the 15,000 rpm disks in our PowerVault MD3000is
Kristoffer No, it's really strange...same server, same everything, only the disks are different
Marc-Dell The controller is different too, no?
Kristoffer No, I moved both volumes to the same controller. I miss some performance statistics or graphs in the storage manager... what do you guys use?
DELL-ToddM For PowerVault MD3000i, Windows perfmon on the host
Kristoffer I plan to graph the performance with SNMP and Nagios, but is there some kind of "free" statistics tool with a nice Web front end? :)
Kristoffer Sure, I could do that
DELL-ToddM You are running Xen on Linux though aren't you
Kristoffer Yes ;) but I have windows running in virtual machines
DELL-ToddM And the virtual machines are attached through software iSCSI initiator to the PowerVault MD3000i?
Kristoffer Yes, open-iSCSI. It would just be nice to have some kind of idea about disk access, cache statistics, etc.
DELL-ToddM That is, the initiator is in the VM
Kristoffer No, the initiator is in the host...the VMs just see a normal disk attached to them. All iSCSI failover/load balancing, etc. is only done on the host
DELL-ToddM Okay, I like that approach better
Kristoffer This way I've got two 15,000 disks to give me 100+ MB/sec. under optimal conditions
DELL-ToddM Not sure what to recommend for performance monitoring of PowerVault MD3000i from Linux. Let me ask our Linux gurus what they use
Kristoffer Sure, would be cool :D
DELL-ToddM I will post as a comment to the home page for this chat
Kristoffer But the tools should be for the entire PowerVault MD3000i, not per partition to see which clients use up all the I/o's ;)
DELL-ToddM Understood. Well, we are over time just a bit. I want to thank everybody for attending and particiapting
Marc-Dell So long
Kristoffer Thanks and bye guys :)
Marc-Dell Thanks for coming!
DELL-ToddM We'll see everybody next week for another iSCSI chat!
Marc-Dell ::smoke