thinking sysadmin

• Prediction: Citrix will drop the open source Xen hypervisor for Hyper-V. The rest of the open source world drops Xen for KVM. – Lengthy speculation about the future of Xen now that Hyper-V is out. If this turns out to be correct, I think it leaves Sun in a particularly awkward spot, given that the work they’ve done on integrating Xen with Solaris. (Seen at virtualization.info and vinternals.)

Am I the only one that hates VMware’s patch download site and its corresponding applet? (Maybe – I couldn’t find anyone complaining about it looking quickly on VMware’s message boards, which I found most odd.) I’ve never been able to get it to launch under Firefox, only under IE (even on the same machine with the same JVM). And when it does launch, it is slow as molasses.
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For grins, I tried a quick-and-dirty BFU of a SXCE 79 instance running on EC2 to the latest nightly build this morning. I roughly followed Ben Rockwood’s BFU instructions and didn’t do anything to resolve conflicts beyond running acr. On reboot, it looks like the system panicked – I presume the reason is probably somewhere in here. Console dump after the jump for the curious.
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• The Register: Sun’s Niagara 3 will have 16-cores and 16 threads per core – “Each socket is chewing through an insane 256 threads.” I do love a good rumor.
• CloudStatus – Just-launched website for monitoring each Amazon Web Services component in more detail than Amazon gives you. Seen at O’Reilly Radar.

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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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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• 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?

Generally, I’m a fan of Sun Microsystems. For the most part, I like their hardware and their software – and their best products show real innovation and willingness to take risks. I’m also a fan of Amazon’s EC2 product, so the announcement that Sun would be officially bundling OpenSolaris for EC2 was great news. Unfortunately, it seems that after all the hullabaloo, Sun doesn’t really want to make it that easy for you to actually use OpenSolaris on EC2, by managing access to it like a control freak would.
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I just finished reading a paper presented at FAST ’08 from the University of Wisconsin, Madison (including the first and senior authors) and NetApp: Parity Lost and Parity Regained. The paper discusses the concept of parity pollution, where, in the words of the authors, “corrupt data in one block of a stripe spreads to other blocks through various parity calculations.”

With the NetApp employees as (middle) authors, the paper seems to have a slight orientation towards a NetApp perspective, but it does mention other filesystems, including ZFS both specifically and later by implication when discussing filesystems that use parental checksums, RAID and scrubbing to protect data. (Interestingly, the first specific mention of ZFS contains a gaffe where they refer to it using “RAID-4″ instead of RAID-Z.) The authors make an attempt to quantify the probability of loss or corruption – arriving at 0.486% probability per year for RAID-Scrub-Parent Checksum (implying ZFS) and 0.031% probability per year for RAID-Scrub-Block Checksum-Physical ID-Logical ID (WAFL) when using nearline drives in a 4 data disk, 1 parity disk RAID configuration and a read-write-scrub access pattern of 0.2-0.2-0.6.
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poptart> version
NetApp Release 7.2.4L1: Wed Nov 21 00:49:33 PST 2007
poptart> aggr add aggr0 11
Aggregate size 8.48 TB exceeds limit 7.00 TB
aggr add: Can not add specified disks to the aggregate because the aggregate size limit for this system type would be exceeded.
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