thinking sysadmin

• Red Hat adopts KVM: what happens to Xen now? – I work in a VMware ESX shop right now (other than all those Solaris Zones and FreeBSD Jails and OpenVZ VEs, that is) – no Xen or KVM. However, given the serious pain in the butt that timekeeping is in Linux guests on ESX, I’ve been sorely tempted to look at running Xen for some Linux virtuals under CentOS 5, in the hopes that this isn’t a problem there. Guess I’ll hold off on that now. (Yeah, I’ve read all the docs, and Linux time sync generally sorta kinda usually works until it doesn’t – it just shouldn’t be that much of a flail.)
• 10 Gigabit Ethernet and VMware – A Match Made in Heaven – Lengthy and interesting article on 10GbE, VMware, consolidation and datacenter Ethernet – dismissive of Infiniband’s chances of becoming the One True Network Fabric.
• Blocks and Files: Between a server or storage array place – More commentary on Chuck’s commentary on HP’s flash announcement. Quote: “Another aspect of this is that a flash SSD cache for a servers needs to plug in to the server’s bus and the supplier doesn’t have to worry about getting a Fibre Channel interface onto flash SSDs which is needed to plug them into existing Fibre Channel slots in a storage array. STEC has an effective monopoly on this (with EMC having its own mini-monopoly because of its exclusivity deal with STEC which ends in a few months) until Emulex’ SSD-tweaked SATA-to-FC bridge chip becomes available at the end of the year. ” Which is probably why NetApp recently announced this instead of flash drives.

Chuck’s got another, uh, thought-provoking blog post up, More Examples Of Why Server Vendors Just Don’t Get Storage, surely intended to ruffle a few feathers. And he does raise some really good points: Most server vendors need more of an SSD strategy than just making a flash drive an option (it’s how you use it, not that you have it!). And as big a fan as I am of ZFS and Sun’s storage options in general, to win in the “enterprise” (and not just, say, HPC) Sun needs to pull everything together into Solaris (from OpenSolaris) and make it less of a DIY operation.
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• HP servers to get flash memory I/O boost – It looks like SSDs will become a common option on server hardware; the real issue will be how to adapt your operating system/file system/application to use them optimally.
• BlueArc’s Titanic benchmark holed – A storage vendor using a non-real-world configuration to optimize benchmark results? Really? Say it ain’t so!

• Cloud Computing: Is the Cloud There Yet? – A Brief History: A mostly negative look at the prospects for cloud computing. Although the arguments it makes are fairly reasonable, the article appears to presume that cloud computing is an all-or-nothing proposal, not a tool for only some tasks. Also odd – “Many routine tasks which are not processor intensive and time critical are the most likely candidates to be migrated to cloud computing” seems wrong (think Sun’s network.com, or how SmugMug uses EC2). Further, the article seems to ignore that big pharma and financial institutions are the largest users of AWS. Still, all in all, a perspective worth considering. (Originally seen at InsideHPC.com.)
• What he said! – scalability.org: Joe Landman on “IT clusters. They are not HPC clusters by any stretch of the imagination. They don’t really work well. Some things sorta-kinda work. Lots of things don’t or cannot. You have some interesting failure modes.” I’ve seen exactly what he’s talking about from the biosciences arm of a large hardware/services company, where they sold something that was high margin, poorly configured, had a lousy interconnect, and, yes, was running RHEL. The article’s use of “IT” as a disparaging term was also interesting. (Also seen at InsideHPC.)
• EMC flashing CLARiiON? – Rumor that flash from EMC is slowly starting to march down-market.

There’s been a lot of noise from the storage industry about flash recently – in particular, noise from EMC and Sun, both of whom recently announced storage products using flash, EMC in January and Sun earlier this month. Below are my thoughts on what EMC and Sun are doing, as well as what NetApp might do. Since I see a fair amount of visitors from all three companies here, if I’ve got something about your employer wrong, please correct me in the comments.
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• Adam Leventhal’s Weblog: Flash, Hybrid Pools, and Future Storage – Excerpts from a forthcoming ACM article on hybrid (flash-disk) storage pools, including: “Flash should be viewed not as a replacement for existing storage, but rather as a means to enhance it. [...] By combining the use of flash as an intent-log to reduce write latency with flash as a cache to reduce read latency, we can create a system that performs far better and consumes less power than other system of similar cost.” Which perhaps could be thought of as a dig at EMC’s flash implementation, although I doubt that’s how the author intended it. (Seen at c0t0d0s0.)

• Jonathan’s Blog: Anything But a Flash in the Pan – Jonathan Schwartz on Sun’s soon-to-be-released (late this year) flash drives. Quote: “ZFS will transparently incorporate Flash into the storage hierarchy of a running system, using the microprocessor cache for the most performance sensitive tasks, DRAM for the next, then Flash, then disk (then ultimately tape).” Speaking of tiered storage, I wonder how flash drives would work within a SAM-QFS implementation – and if SAM-QFS is destined to wither in the shadow of ZFS: Sure it’s open source now, but where is it going these days?