We have tested it under high load and it has performed well, here's the boot log, nothing bug related was there: Xen Minimal OS! start_info: 0xb1a000(VA) nr_pages: 0x6cc00 shared_inf: 0xbff4a000(MA) pt_base: 0xb1d000(VA) nr_pt_frames: 0x9 mfn_list: 0x967000(VA) mod_start: 0x0(VA) mod_len: 0 flags: 0x0 cmd_line: root=/dev/sda1 ro 4 stack: 0x946780-0x966780 MM: Init _text: 0x0(VA) _etext: 0x621f5(VA) _erodata: 0x76000(VA) _edata: 0x7b6d4(VA) stack start: 0x946780(VA) _end: 0x966d34(VA) start_pfn: b29 max_pfn: 6cc00 Mapping memory range 0xc00000 - 0x6cc00000 setting 0x0-0x76000 readonly skipped 0x1000 MM: Initialise page allocator for e8a000(e8a000)-0(6cc00000) MM: done Demand map pfns at 6cc01000-7cc01000. Heap resides at 7cc02000-bcc02000. Initialising timer interface Initialising console ... done. gnttab_table mapped at 0x6cc01000. Initialising scheduler Thread "Idle": pointer: 0x7cc02008, stack: 0x6c850000 Initialising xenbus Thread "xenstore": pointer: 0x7cc02478, stack: 0x6c860000 Dummy main: start_info=0x966880 Thread "main": pointer: 0x7cc028e8, stack: 0x6c870000 "main" "root=/dev/sda1" "ro" "4" vbd 2049 is hd0 ******************* BLKFRONT for device/vbd/2049 ********** backend at /local/domain/0/backend/vbd/15/2049 Failed to read /local/domain/0/backend/vbd/15/2049/feature-barrier. Failed to read /local/domain/0/backend/vbd/15/2049/feature-flush-cache. 16777216 sectors of 0 bytes ************************** vbd 2050 is hd1 ******************* BLKFRONT for device/vbd/2050 ********** backend at /local/domain/0/backend/vbd/15/2050 Failed to read /local/domain/0/backend/vbd/15/2050/feature-barrier. Failed to read /local/domain/0/backend/vbd/15/2050/feature-flush-cache. 712971264 sectors of 0 bytes ************************** vbd 2051 is hd2 ******************* BLKFRONT for device/vbd/2051 ********** backend at /local/domain/0/backend/vbd/15/2051 Failed to read /local/domain/0/backend/vbd/15/2051/feature-barrier. Failed to read /local/domain/0/backend/vbd/15/2051/feature-flush-cache. 1835008 sectors of 0 bytes ************************** [H [J Booting 'Ubuntu 11.04, kernel 2.6.38-13-virtual' root (hd0) Filesystem type is ext2fs, using whole disk kernel /boot/vmlinuz-2.6.38-13-virtual root=LABEL=uec-rootfs ro console=hvc0 initrd /boot/initrd.img-2.6.38-13-virtual close blk: backend at /local/domain/0/backend/vbd/15/2049 close blk: backend at /local/domain/0/backend/vbd/15/2050 close blk: backend at /local/domain/0/backend/vbd/15/2051 [ 0.000000] Reserving virtual address space above 0xf5800000 [ 0.000000] Initializing cgroup subsys cpuset [ 0.000000] Initializing cgroup subsys cpu [ 0.000000] Linux version 2.6.38-13-virtual (buildd@zirconium) (gcc version 4.5.2 (Ubuntu/Linaro 4.5.2-8ubuntu4) ) #52-Ubuntu SMP Tue Nov 8 18:54:04 UTC 2011 (Ubuntu 2.6.38-13.52-virtual 2.6.38.8) [ 0.000000] ACPI in unprivileged domain disabled [ 0.000000] released 0 pages of unused memory [ 0.000000] BIOS-provided physical RAM map: [ 0.000000] Xen: 0000000000000000 - 00000000000a0000 (usable) [ 0.000000] Xen: 00000000000a0000 - 0000000000100000 (reserved) [ 0.000000] Xen: 0000000000100000 - 000000006d400000 (usable) [ 0.000000] NX (Execute Disable) protection: active [ 0.000000] DMI not present or invalid. [ 0.000000] last_pfn = 0x6d400 max_arch_pfn = 0x1000000 [ 0.000000] init_memory_mapping: 0000000000000000-000000002d3fe000 [ 0.000000] RAMDISK: 00cd2000 - 016bc000 [ 0.000000] 1024MB HIGHMEM available. [ 0.000000] 723MB LOWMEM available. [ 0.000000] mapped low ram: 0 - 2d3fe000 [ 0.000000] low ram: 0 - 2d3fe000 [ 0.000000] Zone PFN ranges: [ 0.000000] DMA 0x00000010 -> 0x00001000 [ 0.000000] Normal 0x00001000 -> 0x0002d3fe [ 0.000000] HighMem 0x0002d3fe -> 0x0006d400 [ 0.000000] Movable zone start PFN for each node [ 0.000000] early_node_map[2] active PFN ranges [ 0.000000] 0: 0x00000010 -> 0x000000a0 [ 0.000000] 0: 0x00000100 -> 0x0006d400 [ 0.000000] Using APIC driver default [ 0.000000] SFI: Simple Firmware Interface v0.81 http://simplefirmware.org [ 0.000000] SMP: Allowing 2 CPUs, 0 hotplug CPUs [ 0.000000] Local APIC disabled by BIOS -- you can enable it with "lapic" [ 0.000000] APIC: disable apic facility [ 0.000000] APIC: switched to apic NOOP [ 0.000000] PM: Registered nosave memory: 00000000000a0000 - 0000000000100000 [ 0.000000] Allocating PCI resources starting at 6d400000 (gap: 6d400000:92c00000) [ 0.000000] Booting paravirtualized kernel on Xen [ 0.000000] Xen version: 3.4.3-2.6.18 (preserve-AD) [ 0.000000] setup_percpu: NR_CPUS:8 nr_cpumask_bits:8 nr_cpu_ids:2 nr_node_ids:1 [ 0.000000] PERCPU: Embedded 13 pages/cpu @ec632000 s32320 r0 d20928 u53248 [ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 443879 [ 0.000000] Kernel command line: root=LABEL=uec-rootfs ro console=hvc0 [ 0.000000] PID hash table entries: 4096 (order: 2, 16384 bytes) [ 0.000000] Dentry cache hash table entries: 131072 (order: 7, 524288 bytes) [ 0.000000] Inode-cache hash table entries: 65536 (order: 6, 262144 bytes) [ 0.000000] Initializing CPU#0 [ 0.000000] allocated 8949440 bytes of page_cgroup [ 0.000000] please try 'cgroup_disable=memory' option if you don't want memory cgroups [ 0.000000] Initializing HighMem for node 0 (0002d3fe:0006d400) [ 0.000000] Memory: 1734640k/1789952k available (5371k kernel code, 46672k reserved, 2600k data, 724k init, 1040392k highmem) [ 0.000000] virtual kernel memory layout: [ 0.000000] fixmap : 0xf5716000 - 0xf57ff000 ( 932 kB) [ 0.000000] pkmap : 0xf5400000 - 0xf5600000 (2048 kB) [ 0.000000] vmalloc : 0xedbfe000 - 0xf53fe000 ( 120 MB) [ 0.000000] lowmem : 0xc0000000 - 0xed3fe000 ( 723 MB) [ 0.000000] .init : 0xc08c9000 - 0xc097e000 ( 724 kB) [ 0.000000] .data : 0xc063ec81 - 0xc08c8ec0 (2600 kB) [ 0.000000] .text : 0xc0100000 - 0xc063ec81 (5371 kB) [ 0.000000] SLUB: Genslabs=15, HWalign=64, Order=0-3, MinObjects=0, CPUs=2, Nodes=1 [ 0.000000] Hierarchical RCU implementation. [ 0.000000] RCU dyntick-idle grace-period acceleration is enabled. [ 0.000000] RCU-based detection of stalled CPUs is disabled. [ 0.000000] NR_IRQS:2304 nr_irqs:288 16 [ 0.000000] Console: colour dummy device 80x25 [ 0.000000] console [tty0] enabled [ 0.000000] console [hvc0] enabled [ 0.000000] installing Xen timer for CPU 0 [ 0.000000] Detected 2333.414 MHz processor. [ 0.004000] Calibrating delay loop (skipped), value calculated using timer frequency.. 4666.82 BogoMIPS (lpj=9333656) [ 0.004000] pid_max: default: 32768 minimum: 301 [ 0.004000] Security Framework initialized [ 0.004000] AppArmor: AppArmor initialized [ 0.004000] Yama: becoming mindful. [ 0.004000] Mount-cache hash table entries: 512 [ 0.004000] Initializing cgroup subsys ns [ 0.004000] ns_cgroup deprecated: consider using the 'clone_children' flag without the ns_cgroup. [ 0.004000] Initializing cgroup subsys cpuacct [ 0.004000] Initializing cgroup subsys memory [ 0.004000] Initializing cgroup subsys devices [ 0.004000] Initializing cgroup subsys freezer [ 0.004000] Initializing cgroup subsys net_cls [ 0.004000] Initializing cgroup subsys blkio [ 0.004000] CPU: Unsupported number of siblings 4 [ 0.004000] SMP alternatives: switching to UP code [ 0.007087] ftrace: allocating 24324 entries in 48 pages [ 0.008073] cpu 0 spinlock event irq 286 [ 0.008117] Performance Events: unsupported p6 CPU model 23 no PMU driver, software events only. [ 0.008900] installing Xen timer for CPU 1 [ 0.008927] cpu 1 spinlock event irq 280 [ 0.008961] SMP alternatives: switching to SMP code [ 0.004000] Initializing CPU#1 [ 0.004000] CPU: Unsupported number of siblings 4 [ 0.012178] Brought up 2 CPUs [ 0.012328] devtmpfs: initialized [ 0.013146] Grant table initialized [ 0.013242] print_constraints: dummy: [ 0.033899] Time: 165:165:165 Date: 165/165/65 [ 0.033972] NET: Registered protocol family 16 [ 0.034142] Trying to unpack rootfs image as initramfs... [ 0.044411] EISA bus registered [ 0.056003] PCI: setting up Xen PCI frontend stub [ 0.057909] bio: create slab at 0 [ 0.058090] ACPI: Interpreter disabled. [ 0.060559] xen_balloon: Initialising balloon driver. [ 0.060597] last_pfn = 0x6d400 max_arch_pfn = 0x1000000 [ 0.060817] vgaarb: loaded [ 0.061202] SCSI subsystem initialized [ 0.064191] usbcore: registered new interface driver usbfs [ 0.064222] usbcore: registered new interface driver hub [ 0.064289] usbcore: registered new device driver usb [ 0.064475] PCI: System does not support PCI [ 0.064486] PCI: System does not support PCI [ 0.064648] NetLabel: Initializing [ 0.064657] NetLabel: domain hash size = 128 [ 0.064665] NetLabel: protocols = UNLABELED CIPSOv4 [ 0.064691] NetLabel: unlabeled traffic allowed by default [ 0.064749] Switching to clocksource xen [ 0.064779] Switched to NOHz mode on CPU #1 [ 0.067250] Switched to NOHz mode on CPU #0 [ 0.072060] Freeing initrd memory: 10152k freed [ 0.077606] AppArmor: AppArmor Filesystem Enabled [ 0.077651] pnp: PnP ACPI: disabled [ 0.077661] PnPBIOS: Disabled [ 0.080635] NET: Registered protocol family 2 [ 0.080720] IP route cache hash table entries: 32768 (order: 5, 131072 bytes) [ 0.080993] TCP established hash table entries: 131072 (order: 8, 1048576 bytes) [ 0.081509] TCP bind hash table entries: 65536 (order: 7, 524288 bytes) [ 0.081769] TCP: Hash tables configured (established 131072 bind 65536) [ 0.081781] TCP reno registered [ 0.081790] UDP hash table entries: 512 (order: 2, 16384 bytes) [ 0.081808] UDP-Lite hash table entries: 512 (order: 2, 16384 bytes) [ 0.081917] NET: Registered protocol family 1 [ 0.082125] platform rtc_cmos: registered platform RTC device (no PNP device found) [ 0.082279] cpufreq-nforce2: No nForce2 chipset. [ 0.082489] audit: initializing netlink socket (disabled) [ 0.082509] type=2000 audit(1321357810.382:1): initialized [ 0.091876] highmem bounce pool size: 64 pages [ 0.091898] HugeTLB registered 2 MB page size, pre-allocated 0 pages [ 0.094646] VFS: Disk quotas dquot_6.5.2 [ 0.094729] Dquot-cache hash table entries: 1024 (order 0, 4096 bytes) [ 0.095770] fuse init (API version 7.16) [ 0.095916] msgmni has been set to 1391 [ 0.096339] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 253) [ 0.096393] io scheduler noop registered [ 0.096401] io scheduler deadline registered [ 0.096423] io scheduler cfq registered (default) [ 0.096562] pci_hotplug: PCI Hot Plug PCI Core version: 0.5 [ 0.096608] pciehp: PCI Express Hot Plug Controller Driver version: 0.4 [ 0.096763] isapnp: Scanning for PnP cards... [ 0.097163] Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled [ 0.449547] isapnp: No Plug & Play device found [ 0.568294] Linux agpgart interface v0.103 [ 0.570405] brd: module loaded [ 0.571424] loop: module loaded [ 0.574742] blkfront device/vbd/2049 num-ring-pages 4 nr_ents 128. [ 0.580123] blkfront device/vbd/2050 num-ring-pages 4 nr_ents 128. [ 0.580848] blkfront: xvda1: barriers disabled [ 0.586406] blkfront device/vbd/2051 num-ring-pages 4 nr_ents 128. [ 0.587859] i2c-core: driver [adp5520] using legacy suspend method [ 0.587871] i2c-core: driver [adp5520] using legacy resume method [ 0.588524] blkfront: xvda2: barriers disabled [ 0.589081] Fixed MDIO Bus: probed [ 0.589178] PPP generic driver version 2.4.2 [ 0.589292] Initialising Xen virtual ethernet driver. [ 0.589832] Setting capacity to 712971264 [ 0.589861] xvda2: detected capacity change from 0 to 365041287168 [ 0.591288] blkfront: xvda3: barriers disabled [ 0.591358] tun: Universal TUN/TAP device driver, 1.6 [ 0.591369] tun: (C) 1999-2004 Max Krasnyansky