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  • Improve disk read performance (multiple files) with threading

    - by pablo
    I need to find a method to read a big number of small files (about 300k files) as fast as possible. Reading them sequentially using FileStream and reading the entire file in a single call takes between 170 and 208 seconds (you know, you re-run, disk cache plays its role and time varies). Then I tried using PInvoke with CreateFile/ReadFile and using FILE_FLAG_SEQUENTIAL_SCAN, but I didn't appreciate any changes. I tried with several threads (divide the big set in chunks and have every thread reading its part) and this way I was able to improve speed just a little bit (not even a 5% with every new thread up to 4). Any ideas on how to find the most effective way to do this?

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  • Very large database, very small portion most being retrieved in real time

    - by mingyeow
    Hi folks, I have an interesting database problem. I have a DB that is 150GB in size. My memory buffer is 8GB. Most of my data is rarely being retrieved, or mainly being retrieved by backend processes. I would very much prefer to keep them around because some features require them. Some of it (namely some tables, and some identifiable parts of certain tables) are used very often in a user facing manner How can I make sure that the latter is always being kept in memory? (there is more than enough space for these) More info: We are on Ruby on rails. The database is MYSQL, our tables are stored using INNODB. We are sharding the data across 2 partitions. Because we are sharding it, we store most of our data using JSON blobs, while indexing only the primary keys

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  • LVM / Device Mapper maps wrong device

    - by DaDaDom
    Hi, I run a LVM setup on a raid1 created by mdadm. md2 is based on sda6 (major:minor 8:6) and sdb6 (8:22). md2 is partition 9:2. The VG on top of md2 has 4 LVs, var, home, usr, tmp. First the problem: While booting it seems as if the device mapper takes the wrong partition for the mapping! Immediately after boot the information is like ~# dmsetup table systemlvm-home: 0 4194304 linear 8:22 384 systemlvm-home: 4194304 16777216 linear 8:22 69206400 systemlvm-home: 20971520 8388608 linear 8:22 119538048 systemlvm-home: 29360128 6291456 linear 8:22 243270016 systemlvm-tmp: 0 2097152 linear 8:22 41943424 systemlvm-usr: 0 10485760 linear 8:22 20971904 systemlvm-var: 0 10485760 linear 8:22 10486144 systemlvm-var: 10485760 6291456 linear 8:22 4194688 systemlvm-var: 16777216 4194304 linear 8:22 44040576 systemlvm-var: 20971520 10485760 linear 8:22 31457664 systemlvm-var: 31457280 20971520 linear 8:22 48234880 systemlvm-var: 52428800 33554432 linear 8:22 85983616 systemlvm-var: 85983232 115343360 linear 8:22 127926656 ~# cat /proc/mdstat Personalities : [raid1] md2 : active (auto-read-only) raid1 sda6[0] 151798080 blocks [2/1] [U_] md0 : active raid1 sda1[0] sdb1[1] 96256 blocks [2/2] [UU] md1 : active raid1 sda2[0] sdb2[1] 2931776 blocks [2/2] [UU] I have to manually "lvchange -an" all LVs, add /dev/sdb6 back to the raid and reactivate the LVs, then all is fine. But it prevents me from automounting the partitions and obviously leads to a bunch of other problems. If everything works fine, the information is like ~$ cat /proc/mdstat Personalities : [raid1] md2 : active raid1 sdb6[1] sda6[0] 151798080 blocks [2/2] [UU] ... ~# dmsetup table systemlvm-home: 0 4194304 linear 9:2 384 systemlvm-home: 4194304 16777216 linear 9:2 69206400 systemlvm-home: 20971520 8388608 linear 9:2 119538048 systemlvm-home: 29360128 6291456 linear 9:2 243270016 systemlvm-tmp: 0 2097152 linear 9:2 41943424 systemlvm-usr: 0 10485760 linear 9:2 20971904 systemlvm-var: 0 10485760 linear 9:2 10486144 systemlvm-var: 10485760 6291456 linear 9:2 4194688 systemlvm-var: 16777216 4194304 linear 9:2 44040576 systemlvm-var: 20971520 10485760 linear 9:2 31457664 systemlvm-var: 31457280 20971520 linear 9:2 48234880 systemlvm-var: 52428800 33554432 linear 9:2 85983616 systemlvm-var: 85983232 115343360 linear 9:2 127926656 I think that LVM for some reason just "takes" /dev/sdb6 which is then missing in the raid. I tried almost all options in the lvm.conf but none seems to work. Below is some more information, like config files. Does anyone have any idea about what is going on here and how to prevent that? If you need any additional information, please let me know Thanks in advance! Dominik The information (off a "repaired" system): ~# cat /etc/debian_version 5.0.4 ~# uname -a Linux kermit 2.6.26-2-686 #1 SMP Wed Feb 10 08:59:21 UTC 2010 i686 GNU/Linux ~# lvm version LVM version: 2.02.39 (2008-06-27) Library version: 1.02.27 (2008-06-25) Driver version: 4.13.0 ~# cat /etc/mdadm/mdadm.conf DEVICE partitions ARRAY /dev/md1 level=raid1 num-devices=2 metadata=00.90 UUID=11e9dc6c:1da99f3f:b3088ca6:c6fe60e9 ARRAY /dev/md0 level=raid1 num-devices=2 metadata=00.90 UUID=92ed1e4b:897361d3:070682b3:3baa4fa1 ARRAY /dev/md2 level=raid1 num-devices=2 metadata=00.90 UUID=601d4642:39dc80d7:96e8bbac:649924ba ~# mount /dev/md1 on / type ext3 (rw,errors=remount-ro) tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) procbususb on /proc/bus/usb type usbfs (rw) udev on /dev type tmpfs (rw,mode=0755) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620) /dev/md0 on /boot type ext3 (rw) /dev/mapper/systemlvm-usr on /usr type reiserfs (rw) /dev/mapper/systemlvm-tmp on /tmp type reiserfs (rw) /dev/mapper/systemlvm-home on /home type reiserfs (rw) /dev/mapper/systemlvm-var on /var type reiserfs (rw) ~# grep -v ^$ /etc/lvm/lvm.conf | grep -v "#" devices { dir = "/dev" scan = [ "/dev" ] preferred_names = [ ] filter = [ "a|/dev/md.*|", "r/.*/" ] cache_dir = "/etc/lvm/cache" cache_file_prefix = "" write_cache_state = 1 sysfs_scan = 1 md_component_detection = 1 ignore_suspended_devices = 0 } log { verbose = 0 syslog = 1 overwrite = 0 level = 0 indent = 1 command_names = 0 prefix = " " } backup { backup = 1 backup_dir = "/etc/lvm/backup" archive = 1 archive_dir = "/etc/lvm/archive" retain_min = 10 retain_days = 30 } shell { history_size = 100 } global { umask = 077 test = 0 units = "h" activation = 1 proc = "/proc" locking_type = 1 fallback_to_clustered_locking = 1 fallback_to_local_locking = 1 locking_dir = "/lib/init/rw" } activation { missing_stripe_filler = "/dev/ioerror" reserved_stack = 256 reserved_memory = 8192 process_priority = -18 mirror_region_size = 512 readahead = "auto" mirror_log_fault_policy = "allocate" mirror_device_fault_policy = "remove" } :~# vgscan -vvv Processing: vgscan -vvv O_DIRECT will be used Setting global/locking_type to 1 File-based locking selected. Setting global/locking_dir to /lib/init/rw Locking /lib/init/rw/P_global WB Wiping cache of LVM-capable devices /dev/block/1:0: Added to device cache /dev/block/1:1: Added to device cache /dev/block/1:10: Added to device cache /dev/block/1:11: Added to device cache /dev/block/1:12: Added to device cache /dev/block/1:13: Added to device cache /dev/block/1:14: Added to device cache /dev/block/1:15: Added to device cache /dev/block/1:2: Added to device cache /dev/block/1:3: Added to device cache /dev/block/1:4: Added to device cache /dev/block/1:5: Added to device cache /dev/block/1:6: Added to device cache /dev/block/1:7: Added to device cache /dev/block/1:8: Added to device cache /dev/block/1:9: Added to device cache /dev/block/253:0: Added to device cache /dev/block/253:1: Added to device cache /dev/block/253:2: Added to device cache /dev/block/253:3: Added to device cache /dev/block/8:0: Added to device cache /dev/block/8:1: Added to device cache /dev/block/8:16: Added to device cache /dev/block/8:17: Added to device cache /dev/block/8:18: Added to device cache /dev/block/8:19: Added to device cache /dev/block/8:2: Added to device cache /dev/block/8:21: Added to device cache /dev/block/8:22: Added to device cache /dev/block/8:3: Added to device cache /dev/block/8:5: Added to device cache /dev/block/8:6: Added to device cache /dev/block/9:0: Already in device cache /dev/block/9:1: Already in device cache /dev/block/9:2: Already in device cache /dev/bsg/0:0:0:0: Not a block device /dev/bsg/1:0:0:0: Not a block device /dev/bus/usb/001/001: Not a block device [... many more "not a block device"] /dev/core: Not a block device /dev/cpu_dma_latency: Not a block device /dev/disk/by-id/ata-SAMSUNG_HD160JJ_S08HJ10L507895: Aliased to /dev/block/8:16 in device cache /dev/disk/by-id/ata-SAMSUNG_HD160JJ_S08HJ10L507895-part1: Aliased to /dev/block/8:17 in device cache /dev/disk/by-id/ata-SAMSUNG_HD160JJ_S08HJ10L507895-part2: Aliased to /dev/block/8:18 in device cache /dev/disk/by-id/ata-SAMSUNG_HD160JJ_S08HJ10L507895-part3: Aliased to /dev/block/8:19 in device cache /dev/disk/by-id/ata-SAMSUNG_HD160JJ_S08HJ10L507895-part5: Aliased to /dev/block/8:21 in device cache /dev/disk/by-id/ata-SAMSUNG_HD160JJ_S08HJ10L507895-part6: Aliased to /dev/block/8:22 in device cache /dev/disk/by-id/ata-SAMSUNG_HD160JJ_S08HJ10L526800: Aliased to /dev/block/8:0 in device cache /dev/disk/by-id/ata-SAMSUNG_HD160JJ_S08HJ10L526800-part1: Aliased to /dev/block/8:1 in device cache /dev/disk/by-id/ata-SAMSUNG_HD160JJ_S08HJ10L526800-part2: Aliased to /dev/block/8:2 in device cache /dev/disk/by-id/ata-SAMSUNG_HD160JJ_S08HJ10L526800-part3: Aliased to /dev/block/8:3 in device cache /dev/disk/by-id/ata-SAMSUNG_HD160JJ_S08HJ10L526800-part5: Aliased to /dev/block/8:5 in device cache /dev/disk/by-id/ata-SAMSUNG_HD160JJ_S08HJ10L526800-part6: Aliased to /dev/block/8:6 in device cache /dev/disk/by-id/dm-name-systemlvm-home: Aliased to /dev/block/253:2 in device cache /dev/disk/by-id/dm-name-systemlvm-tmp: Aliased to /dev/block/253:3 in device cache /dev/disk/by-id/dm-name-systemlvm-usr: Aliased to /dev/block/253:1 in device cache /dev/disk/by-id/dm-name-systemlvm-var: Aliased to /dev/block/253:0 in device cache /dev/disk/by-id/dm-uuid-LVM-rL8Oq2dA7oeRYeu1orJA7Ufnb1kjOyvr25N7CRZpUMzR18NfS6zeSeAVnVT98LuU: Aliased to /dev/block/253:0 in device cache /dev/disk/by-id/dm-uuid-LVM-rL8Oq2dA7oeRYeu1orJA7Ufnb1kjOyvr3TpFXtLjYGEwn79IdXsSCZPl8AxmqbmQ: Aliased to /dev/block/253:1 in device cache /dev/disk/by-id/dm-uuid-LVM-rL8Oq2dA7oeRYeu1orJA7Ufnb1kjOyvrc5MJ4KolevMjt85PPBrQuRTkXbx6NvTi: Aliased to /dev/block/253:3 in device cache /dev/disk/by-id/dm-uuid-LVM-rL8Oq2dA7oeRYeu1orJA7Ufnb1kjOyvrYXrfdg5OSYDVkNeiQeQksgCI849Z2hx8: Aliased to /dev/block/253:2 in device cache /dev/disk/by-id/md-uuid-11e9dc6c:1da99f3f:b3088ca6:c6fe60e9: Already in device cache /dev/disk/by-id/md-uuid-601d4642:39dc80d7:96e8bbac:649924ba: Already in device cache /dev/disk/by-id/md-uuid-92ed1e4b:897361d3:070682b3:3baa4fa1: Already in device cache /dev/disk/by-id/scsi-SATA_SAMSUNG_HD160JJS08HJ10L507895: Aliased to /dev/block/8:16 in device cache /dev/disk/by-id/scsi-SATA_SAMSUNG_HD160JJS08HJ10L507895-part1: Aliased to /dev/block/8:17 in device cache /dev/disk/by-id/scsi-SATA_SAMSUNG_HD160JJS08HJ10L507895-part2: Aliased to /dev/block/8:18 in device cache /dev/disk/by-id/scsi-SATA_SAMSUNG_HD160JJS08HJ10L507895-part3: Aliased to /dev/block/8:19 in device cache /dev/disk/by-id/scsi-SATA_SAMSUNG_HD160JJS08HJ10L507895-part5: Aliased to /dev/block/8:21 in device cache /dev/disk/by-id/scsi-SATA_SAMSUNG_HD160JJS08HJ10L507895-part6: Aliased to /dev/block/8:22 in device cache /dev/disk/by-id/scsi-SATA_SAMSUNG_HD160JJS08HJ10L526800: Aliased to /dev/block/8:0 in device cache /dev/disk/by-id/scsi-SATA_SAMSUNG_HD160JJS08HJ10L526800-part1: Aliased to /dev/block/8:1 in device cache /dev/disk/by-id/scsi-SATA_SAMSUNG_HD160JJS08HJ10L526800-part2: Aliased to /dev/block/8:2 in device cache /dev/disk/by-id/scsi-SATA_SAMSUNG_HD160JJS08HJ10L526800-part3: Aliased to /dev/block/8:3 in device cache /dev/disk/by-id/scsi-SATA_SAMSUNG_HD160JJS08HJ10L526800-part5: Aliased to /dev/block/8:5 in device cache /dev/disk/by-id/scsi-SATA_SAMSUNG_HD160JJS08HJ10L526800-part6: Aliased to /dev/block/8:6 in device cache /dev/disk/by-path/pci-0000:00:0f.0-scsi-0:0:0:0: Aliased to /dev/block/8:0 in device cache /dev/disk/by-path/pci-0000:00:0f.0-scsi-0:0:0:0-part1: Aliased to /dev/block/8:1 in device cache /dev/disk/by-path/pci-0000:00:0f.0-scsi-0:0:0:0-part2: Aliased to /dev/block/8:2 in device cache /dev/disk/by-path/pci-0000:00:0f.0-scsi-0:0:0:0-part3: Aliased to /dev/block/8:3 in device cache /dev/disk/by-path/pci-0000:00:0f.0-scsi-0:0:0:0-part5: Aliased to /dev/block/8:5 in device cache /dev/disk/by-path/pci-0000:00:0f.0-scsi-0:0:0:0-part6: Aliased to /dev/block/8:6 in device cache /dev/disk/by-path/pci-0000:00:0f.0-scsi-1:0:0:0: Aliased to /dev/block/8:16 in device cache /dev/disk/by-path/pci-0000:00:0f.0-scsi-1:0:0:0-part1: Aliased to /dev/block/8:17 in device cache /dev/disk/by-path/pci-0000:00:0f.0-scsi-1:0:0:0-part2: Aliased to /dev/block/8:18 in device cache /dev/disk/by-path/pci-0000:00:0f.0-scsi-1:0:0:0-part3: Aliased to /dev/block/8:19 in device cache /dev/disk/by-path/pci-0000:00:0f.0-scsi-1:0:0:0-part5: Aliased to /dev/block/8:21 in device cache /dev/disk/by-path/pci-0000:00:0f.0-scsi-1:0:0:0-part6: Aliased to /dev/block/8:22 in device cache /dev/disk/by-uuid/13c1262b-e06f-40ce-b088-ce410640a6dc: Aliased to /dev/block/253:3 in device cache /dev/disk/by-uuid/379f57b0-2e03-414c-808a-f76160617336: Aliased to /dev/block/253:2 in device cache /dev/disk/by-uuid/4fb2d6d3-bd51-48d3-95ee-8e404faf243d: Already in device cache /dev/disk/by-uuid/5c6728ec-82c1-49c0-93c5-f6dbd5c0d659: Aliased to /dev/block/8:5 in device cache /dev/disk/by-uuid/a13cdfcd-2191-4185-a727-ffefaf7a382e: Aliased to /dev/block/253:1 in device cache /dev/disk/by-uuid/e0d5893d-ff88-412f-b753-9e3e9af3242d: Aliased to /dev/block/8:21 in device cache /dev/disk/by-uuid/e79c9da6-8533-4e55-93ec-208876671edc: Aliased to /dev/block/253:0 in device cache /dev/disk/by-uuid/f3f176f5-12f7-4af8-952a-c6ac43a6e332: Already in device cache /dev/dm-0: Aliased to /dev/block/253:0 in device cache (preferred name) /dev/dm-1: Aliased to /dev/block/253:1 in device cache (preferred name) /dev/dm-2: Aliased to /dev/block/253:2 in device cache (preferred name) /dev/dm-3: Aliased to /dev/block/253:3 in device cache (preferred name) /dev/fd: Symbolic link to directory /dev/full: Not a block device /dev/hpet: Not a block device /dev/initctl: Not a block device /dev/input/by-path/platform-i8042-serio-0-event-kbd: Not a block device /dev/input/event0: Not a block device /dev/input/mice: Not a block device /dev/kmem: Not a block device /dev/kmsg: Not a block device /dev/log: Not a block device /dev/loop/0: Added to device cache /dev/MAKEDEV: Not a block device /dev/mapper/control: Not a block device /dev/mapper/systemlvm-home: Aliased to /dev/dm-2 in device cache /dev/mapper/systemlvm-tmp: Aliased to /dev/dm-3 in device cache /dev/mapper/systemlvm-usr: Aliased to /dev/dm-1 in device cache /dev/mapper/systemlvm-var: Aliased to /dev/dm-0 in device cache /dev/md0: Already in device cache /dev/md1: Already in device cache /dev/md2: Already in device cache /dev/mem: Not a block device /dev/net/tun: Not a block device /dev/network_latency: Not a block device /dev/network_throughput: Not a block device /dev/null: Not a block device /dev/port: Not a block device /dev/ppp: Not a block device /dev/psaux: Not a block device /dev/ptmx: Not a block device /dev/pts/0: Not a block device /dev/ram0: Aliased to /dev/block/1:0 in device cache (preferred name) /dev/ram1: Aliased to /dev/block/1:1 in device cache (preferred name) /dev/ram10: Aliased to /dev/block/1:10 in device cache (preferred name) /dev/ram11: Aliased to /dev/block/1:11 in device cache (preferred name) /dev/ram12: Aliased to /dev/block/1:12 in device cache (preferred name) /dev/ram13: Aliased to /dev/block/1:13 in device cache (preferred name) /dev/ram14: Aliased to /dev/block/1:14 in device cache (preferred name) /dev/ram15: Aliased to /dev/block/1:15 in device cache (preferred name) /dev/ram2: Aliased to /dev/block/1:2 in device cache (preferred name) /dev/ram3: Aliased to /dev/block/1:3 in device cache (preferred name) /dev/ram4: Aliased to /dev/block/1:4 in device cache (preferred name) /dev/ram5: Aliased to /dev/block/1:5 in device cache (preferred name) /dev/ram6: Aliased to /dev/block/1:6 in device cache (preferred name) /dev/ram7: Aliased to /dev/block/1:7 in device cache (preferred name) /dev/ram8: Aliased to /dev/block/1:8 in device cache (preferred name) /dev/ram9: Aliased to /dev/block/1:9 in device cache (preferred name) /dev/random: Not a block device /dev/root: Already in device cache /dev/rtc: Not a block device /dev/rtc0: Not a block device /dev/sda: Aliased to /dev/block/8:0 in device cache (preferred name) /dev/sda1: Aliased to /dev/block/8:1 in device cache (preferred name) /dev/sda2: Aliased to /dev/block/8:2 in device cache (preferred name) /dev/sda3: Aliased to /dev/block/8:3 in device cache (preferred name) /dev/sda5: Aliased to /dev/block/8:5 in device cache (preferred name) /dev/sda6: Aliased to /dev/block/8:6 in device cache (preferred name) /dev/sdb: Aliased to /dev/block/8:16 in device cache (preferred name) /dev/sdb1: Aliased to /dev/block/8:17 in device cache (preferred name) /dev/sdb2: Aliased to /dev/block/8:18 in device cache (preferred name) /dev/sdb3: Aliased to /dev/block/8:19 in device cache (preferred name) /dev/sdb5: Aliased to /dev/block/8:21 in device cache (preferred name) /dev/sdb6: Aliased to /dev/block/8:22 in device cache (preferred name) /dev/shm/network/ifstate: Not a block device /dev/snapshot: Not a block device /dev/sndstat: stat failed: Datei oder Verzeichnis nicht gefunden /dev/stderr: Not a block device /dev/stdin: Not a block device /dev/stdout: Not a block device /dev/systemlvm/home: Aliased to /dev/dm-2 in device cache /dev/systemlvm/tmp: Aliased to /dev/dm-3 in device cache /dev/systemlvm/usr: Aliased to /dev/dm-1 in device cache /dev/systemlvm/var: Aliased to /dev/dm-0 in device cache /dev/tty: Not a block device /dev/tty0: Not a block device [... many more "not a block device"] /dev/vcsa6: Not a block device /dev/xconsole: Not a block device /dev/zero: Not a block device Wiping internal VG cache lvmcache: initialised VG #orphans_lvm1 lvmcache: initialised VG #orphans_pool lvmcache: initialised VG #orphans_lvm2 Reading all physical volumes. This may take a while... Finding all volume groups /dev/ram0: Skipping (regex) /dev/loop/0: Skipping (sysfs) /dev/sda: Skipping (regex) Opened /dev/md0 RO /dev/md0: size is 192512 sectors Closed /dev/md0 /dev/md0: size is 192512 sectors Opened /dev/md0 RW O_DIRECT /dev/md0: block size is 1024 bytes Closed /dev/md0 Using /dev/md0 Opened /dev/md0 RW O_DIRECT /dev/md0: block size is 1024 bytes /dev/md0: No label detected Closed /dev/md0 /dev/dm-0: Skipping (regex) /dev/ram1: Skipping (regex) /dev/sda1: Skipping (regex) Opened /dev/md1 RO /dev/md1: size is 5863552 sectors Closed /dev/md1 /dev/md1: size is 5863552 sectors Opened /dev/md1 RW O_DIRECT /dev/md1: block size is 4096 bytes Closed /dev/md1 Using /dev/md1 Opened /dev/md1 RW O_DIRECT /dev/md1: block size is 4096 bytes /dev/md1: No label detected Closed /dev/md1 /dev/dm-1: Skipping (regex) /dev/ram2: Skipping (regex) /dev/sda2: Skipping (regex) Opened /dev/md2 RO /dev/md2: size is 303596160 sectors Closed /dev/md2 /dev/md2: size is 303596160 sectors Opened /dev/md2 RW O_DIRECT /dev/md2: block size is 4096 bytes Closed /dev/md2 Using /dev/md2 Opened /dev/md2 RW O_DIRECT /dev/md2: block size is 4096 bytes /dev/md2: lvm2 label detected lvmcache: /dev/md2: now in VG #orphans_lvm2 (#orphans_lvm2) /dev/md2: Found metadata at 39936 size 2632 (in area at 2048 size 194560) for systemlvm (rL8Oq2-dA7o-eRYe-u1or-JA7U-fnb1-kjOyvr) lvmcache: /dev/md2: now in VG systemlvm with 1 mdas lvmcache: /dev/md2: setting systemlvm VGID to rL8Oq2dA7oeRYeu1orJA7Ufnb1kjOyvr lvmcache: /dev/md2: VG systemlvm: Set creation host to rescue. Closed /dev/md2 /dev/dm-2: Skipping (regex) /dev/ram3: Skipping (regex) /dev/sda3: Skipping (regex) /dev/dm-3: Skipping (regex) /dev/ram4: Skipping (regex) /dev/ram5: Skipping (regex) /dev/sda5: Skipping (regex) /dev/ram6: Skipping (regex) /dev/sda6: Skipping (regex) /dev/ram7: Skipping (regex) /dev/ram8: Skipping (regex) /dev/ram9: Skipping (regex) /dev/ram10: Skipping (regex) /dev/ram11: Skipping (regex) /dev/ram12: Skipping (regex) /dev/ram13: Skipping (regex) /dev/ram14: Skipping (regex) /dev/ram15: Skipping (regex) /dev/sdb: Skipping (regex) /dev/sdb1: Skipping (regex) /dev/sdb2: Skipping (regex) /dev/sdb3: Skipping (regex) /dev/sdb5: Skipping (regex) /dev/sdb6: Skipping (regex) Locking /lib/init/rw/V_systemlvm RB Finding volume group "systemlvm" Opened /dev/md2 RW O_DIRECT /dev/md2: block size is 4096 bytes /dev/md2: lvm2 label detected lvmcache: /dev/md2: now in VG #orphans_lvm2 (#orphans_lvm2) with 1 mdas /dev/md2: Found metadata at 39936 size 2632 (in area at 2048 size 194560) for systemlvm (rL8Oq2-dA7o-eRYe-u1or-JA7U-fnb1-kjOyvr) lvmcache: /dev/md2: now in VG systemlvm with 1 mdas lvmcache: /dev/md2: setting systemlvm VGID to rL8Oq2dA7oeRYeu1orJA7Ufnb1kjOyvr lvmcache: /dev/md2: VG systemlvm: Set creation host to rescue. Using cached label for /dev/md2 Read systemlvm metadata (19) from /dev/md2 at 39936 size 2632 /dev/md2 0: 0 16: home(0:0) /dev/md2 1: 16 24: var(40:0) /dev/md2 2: 40 40: var(0:0) /dev/md2 3: 80 40: usr(0:0) /dev/md2 4: 120 40: var(80:0) /dev/md2 5: 160 8: tmp(0:0) /dev/md2 6: 168 16: var(64:0) /dev/md2 7: 184 80: var(120:0) /dev/md2 8: 264 64: home(16:0) /dev/md2 9: 328 128: var(200:0) /dev/md2 10: 456 32: home(80:0) /dev/md2 11: 488 440: var(328:0) /dev/md2 12: 928 24: home(112:0) /dev/md2 13: 952 206: NULL(0:0) Found volume group "systemlvm" using metadata type lvm2 Read volume group systemlvm from /etc/lvm/backup/systemlvm Unlocking /lib/init/rw/V_systemlvm Closed /dev/md2 Unlocking /lib/init/rw/P_global ~# vgdisplay --- Volume group --- VG Name systemlvm System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 19 VG Access read/write VG Status resizable MAX LV 0 Cur LV 4 Open LV 4 Max PV 0 Cur PV 1 Act PV 1 VG Size 144,75 GB PE Size 128,00 MB Total PE 1158 Alloc PE / Size 952 / 119,00 GB Free PE / Size 206 / 25,75 GB VG UUID rL8Oq2-dA7o-eRYe-u1or-JA7U-fnb1-kjOyvr ~# pvdisplay --- Physical volume --- PV Name /dev/md2 VG Name systemlvm PV Size 144,77 GB / not usable 16,31 MB Allocatable yes PE Size (KByte) 131072 Total PE 1158 Free PE 206 Allocated PE 952 PV UUID ZSAzP5-iBvr-L7jy-wB8T-AiWz-0g3m-HLK66Y :~# lvdisplay --- Logical volume --- LV Name /dev/systemlvm/home VG Name systemlvm LV UUID YXrfdg-5OSY-DVkN-eiQe-Qksg-CI84-9Z2hx8 LV Write Access read/write LV Status available # open 2 LV Size 17,00 GB Current LE 136 Segments 4 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:2 --- Logical volume --- LV Name /dev/systemlvm/var VG Name systemlvm LV UUID 25N7CR-ZpUM-zR18-NfS6-zeSe-AVnV-T98LuU LV Write Access read/write LV Status available # open 2 LV Size 96,00 GB Current LE 768 Segments 7 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0 --- Logical volume --- LV Name /dev/systemlvm/usr VG Name systemlvm LV UUID 3TpFXt-LjYG-Ewn7-9IdX-sSCZ-Pl8A-xmqbmQ LV Write Access read/write LV Status available # open 2 LV Size 5,00 GB Current LE 40 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:1 --- Logical volume --- LV Name /dev/systemlvm/tmp VG Name systemlvm LV UUID c5MJ4K-olev-Mjt8-5PPB-rQuR-TkXb-x6NvTi LV Write Access read/write LV Status available # open 2 LV Size 1,00 GB Current LE 8 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:3

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  • The Beginner’s Guide to Linux Disk Utilities

    - by Zainul Franciscus
    Knowing how to check the condition of your hard disk is useful to determine when to replace your hard disk. In today’s article, we will show you some Linux disk utilities to diagnose the health of your hard disk. Image by Scoobay Latest Features How-To Geek ETC The Complete List of iPad Tips, Tricks, and Tutorials The 50 Best Registry Hacks that Make Windows Better The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor The Brothers Mario – Epic Gangland Style Mario Brothers Movie Trailer [Video] Score Awesome Games on the Cheap with the Humble Indie Bundle Add a Colorful Christmas Theme to Your Windows 7 Desktop This Windows Hack Changes the Blue Screen of Death to Red Edit Images Quickly in Firefox with Pixlr Grabber Zoho Writer, Sheet, and Show Now Available in Chrome Web Store

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  • Edinburgh this Thurs (25th) - Rob Carrol talks about how to build a high performance, scalable repor

    - by tonyrogerson
    Scottish Area SQL Server User Group Meeting, Edinburgh - Thursday 25th March An evening of SQL Server 2008 Reporting Services Scalability and Performance with Rob Carrol, see how to build a high performance, scalable reporting platform and the tuning techniques required to ensure that report performance remains optimal as your platform grows. Pizza and drinks will be provided! Register at http://www.sqlserverfaq.com/events/221/SQL-Server-2008-Reporting-Services-Scalability-and-Performance.aspx...(read more)

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  • Exchange 2010 - resolving Calendar Attendant\Requests Failed

    - by marcwenger
    On my mailbox server, I am receiving the alert: MSExchange Calendar Attendant\Requests Failed Or in Solarwinds Requests Failed (Calendar Attendant) for Exchange 2010 Mailbox Role Counters (Advanced) on *servername* All I know is this figure should be 0 at all times. Currently I am at 2 and this is the only alert on the Exchange servers. No where I can find how to resolve this. How can I fix this? thank you

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  • SQL SERVER – Maximize Database Performance with DB Optimizer – SQL in Sixty Seconds #054

    - by Pinal Dave
    Performance tuning is an interesting concept and everybody evaluates it differently. Every developer and DBA have different opinion about how one can do performance tuning. I personally believe performance tuning is a three step process Understanding the Query Identifying the Bottleneck Implementing the Fix While, we are working with large database application and it suddenly starts to slow down. We are all under stress about how we can get back the database back to normal speed. Most of the time we do not have enough time to do deep analysis of what is going wrong as well what will fix the problem. Our primary goal at that time is to just fix the database problem as fast as we can. However, here is one very important thing which we need to keep in our mind is that when we do quick fix, it should not create any further issue with other parts of the system. When time is essence and we want to do deep analysis of our system to give us the best solution we often tend to make mistakes. Sometimes we make mistakes as we do not have proper time to analysis the entire system. Here is what I do when I face such a situation – I take the help of DB Optimizer. It is a fantastic tool and does superlative performance tuning of the system. Everytime when I talk about performance tuning tool, the initial reaction of the people is that they do not want to try this as they believe it requires lots of the learning of the tool before they use it. It is absolutely not true with the case of the DB optimizer. It is a very easy to use and self intuitive tool. Once can get going with the product, in no time. Here is a quick video I have build where I demonstrate how we can identify what index is missing for query and how we can quickly create the index. Entire three steps of the query tuning are completed in less than 60 seconds. If you are into performance tuning and query optimization you should download DB Optimizer and give it a go. Let us see the same concept in following SQL in Sixty Seconds Video: You can Download DB Optimizer and reproduce the same Sixty Seconds experience. Related Tips in SQL in Sixty Seconds: Performance Tuning – Part 1 of 2 – Getting Started and Configuration Performance Tuning – Part 2 of 2 – Analysis, Detection, Tuning and Optimizing What would you like to see in the next SQL in Sixty Seconds video? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Interview Questions and Answers, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Identity

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  • Find and free disk space that is unused but unavailable (due to file system error, etc.)

    - by Voyagerfan5761
    Sometimes I get the feeling that if an app such as μTorrent allocates files on my FAT32-formatted flash drive, but then is killed or crashes (as happens more than a few times a month), that space just disappears from my file system. Whether or not that is the case, sometimes I do get a chill from wondering if I've lost hundreds of MB in available storage due to carelessness or malfunctions. Checking my disk with WinDirStat just makes it worse, because I see the huge "<Unknown>" item at the disk root staring at me, eating up well over a gigabyte. It might be FS inefficiency (due to 32 or 64kb sector/cluster size and a lot of tiny files) or it might be a glitch... Is there a tool I can download and run to check my file system and make sure that there aren't any unused allocated blocks on the disk? I want to make sure I'm not losing any disk space to I/O errors, etc.

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  • Why do [flush-8:16] and [jbd2/sdb2-8] occasionally use 99.99% disk IO?

    - by ændrük
    Approximately twice a week, the entire graphical interface will lock up for about 10-20 seconds without warning while I am doing simple tasks such as browsing the web or writing a paper. When this happens, GUI elements do not respond to mouse or keyboard input, and the System Monitor applet displays 100% IOWait processor usage. Today, I finally happened to have GNOME Terminal already open when the problem started. Despite other applications such as Google Chrome, Firefox, GNOME Do, and GNOME Panel being unresponsive, the terminal was usable. I ran iotop and observed that commands named [flush-8:16] and [jbd2/sdb2-8] were alternately using 99.99% IO. What are these, and how can I prevent them from causing GUI unresponsiveness? Here is dumpe2fs /dev/sdb2, if it's relevant.

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  • Need help tuning Mysql and linux server

    - by Newtonx
    We have multi-user application (like MailChimp,Constant Contact) . Each of our customers has it's own contact's list (from 5 to 100.000 contacts). Everything is stored in one BIG database (currently 25G). Since we released our product we have the following data history. 5 years of data history : - users/customers (200+) - contacts (40 million records) - campaigns - campaign_deliveries (73.843.764 records) - campaign_queue ( 8 millions currently ) As we get more users and table records increase our system/web app is getting slower and slower . Some queries takes too long to execute . SCHEMA Table contacts --------------------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------------+------------------+------+-----+---------+----------------+ | contact_id | int(10) unsigned | NO | PRI | NULL | auto_increment | | client_id | int(10) unsigned | YES | | NULL | | | name | varchar(60) | YES | | NULL | | | mail | varchar(60) | YES | MUL | NULL | | | verified | int(1) | YES | | 0 | | | owner | int(10) unsigned | NO | MUL | 0 | | | date_created | date | YES | MUL | NULL | | | geolocation | varchar(100) | YES | | NULL | | | ip | varchar(20) | YES | MUL | NULL | | +---------------------+------------------+------+-----+---------+----------------+ Table campaign_deliveries +---------------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+------------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | newsletter_id | int(10) unsigned | NO | MUL | 0 | | | contact_id | int(10) unsigned | NO | MUL | 0 | | | sent_date | date | YES | MUL | NULL | | | sent_time | time | YES | MUL | NULL | | | smtp_server | varchar(20) | YES | | NULL | | | owner | int(5) | YES | MUL | NULL | | | ip | varchar(20) | YES | MUL | NULL | | +---------------+------------------+------+-----+---------+----------------+ Table campaign_queue +---------------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+------------------+------+-----+---------+----------------+ | queue_id | int(10) unsigned | NO | PRI | NULL | auto_increment | | newsletter_id | int(10) unsigned | NO | MUL | 0 | | | owner | int(10) unsigned | NO | MUL | 0 | | | date_to_send | date | YES | | NULL | | | contact_id | int(11) | NO | MUL | NULL | | | date_created | date | YES | | NULL | | +---------------+------------------+------+-----+---------+----------------+ Slow queries LOG -------------------------------------------- Query_time: 350 Lock_time: 1 Rows_sent: 1 Rows_examined: 971004 SELECT COUNT(*) as total FROM contacts WHERE (contacts.owner = 70 AND contacts.verified = 1); Query_time: 235 Lock_time: 1 Rows_sent: 1 Rows_examined: 4455209 SELECT COUNT(*) as total FROM contacts WHERE (contacts.owner = 2); How can we optimize it ? Queries should take no more than 30 secs to execute? Can we optimize it and keep all data in one BIG database or should we change app's structure and set one single database to each user ? Thanks

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  • When to use Truecrypt, and when not to?

    - by tm77
    I have about 30 (this number will most likely grow over the next few years to 50 or more) unencrypted laptops that I have been tasked to encrypt (entire drive). These machines will be used off site regularly by my users. These machines are running Windows 7 and XP (about 50/50), but more Windows 7 every month. I have experience with Truecrypt, and have had no issues. It appears to be THE solution for a free solution. My concern with Truecrypt is that my users will have 2 passswords needed to login to their machines. Also, I need to choose to either have 1 password for my organization, or carefully document each machine's password (management nightmare). In my mind, choosing between a managed and a free encryption solution is primarily based on the NUMBER of machines that will be encrypted and supported. Two questions: From a management standpoint, what is the tipping point of users where a managed solution would pay for itself over Truecrypt? What are some good third party solutions? (I will consider Bitlocker, but the price to upgrade Windows 7 licenses is a turn-off) I would love to hear from some admins with experience in supporting encrypted machines in a corporate environment. Many thanks in advance!

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  • How do I objectively measure an application's load on a server

    - by Joe
    All, I'm not even sure where to begin looking for resources to answer my question, and I realize that speculation about this kind of thing is highly subjective. I need help determining what class of server I should purchase to host a MS Silverlight application with a MSSQL server back-end on a Windows Server 2008 platform. It's an interactive program, so I can't simply generate a list of URLs to test against, and run it with 1000 simultaneous users. What tools are out there to help me determine what kind of load the application will put on a server at varying levels of concurrent users? Would you all suggest separating the SQL server form the web server, to better differentiate the generated load on the different parts of the stack?

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  • Server configurations for hosting MySQL database

    - by shyam
    I have a web application which uses a MySQL database hosted on a virtual server. I've been using this server when I started the application and when the database was really small. Now it has grown and the server is not able to handle the db, causing frequent db errors. I'm planning to get a server and I need suggestions for that. Like I said, the db is now 9 GB, and is growing considerably fast. There are a number of tables with millions of rows, which are frequently updated and queried. The most frequent error the db shows is Lock wait timeout exceeded. Previously there used to be "The total number of locks exceeds the lock table size" errors too, but I could avoid it by increasing Innodb buffer pool size. Please suggest what configurations should I look for in the server I should buy. I read somewhere that the db should ideally have a buffer pool size greater than the size of its data, so in my case I guess I'd need memory gt 9 GB. What other things should I look for in the server? Just tell me if I should give you more info about the

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  • Automount of external hard disk

    - by moose
    I have an Intenso 6002560 1TB Memory Station - an external hard disk. This hard disk gets connected via Y-USB cable. When I connect both USB-ends to my Notebook, it gets recognized by my Ubuntu 10.04.4 LTS system: moose@pc07:~$ lsusb [...] Bus 002 Device 005: ID 13fd:1840 Initio Corporation [...] and Disk /dev/sda: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00065e10 Device Boot Start End Blocks Id System /dev/sda1 * 1 37810 303704064 83 Linux /dev/sda2 37810 38914 8864769 5 Extended /dev/sda5 37810 38914 8864768 82 Linux swap / Solaris Disk /dev/sdc: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0d6ea32a Device Boot Start End Blocks Id System /dev/sdc1 1 121601 976759008+ c W95 FAT32 (LBA) But it did not get mounted: moose@pc07:/dev$ mount -l /dev/sda1 on / type ext4 (rw,errors=remount-ro,user_xattr) proc on /proc type proc (rw,noexec,nosuid,nodev) none on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) none on /dev type devtmpfs (rw,mode=0755) none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) none on /dev/shm type tmpfs (rw,nosuid,nodev) none on /var/run type tmpfs (rw,nosuid,mode=0755) none on /var/lock type tmpfs (rw,noexec,nosuid,nodev) none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755) binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev) gvfs-fuse-daemon on /home/moose/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=moose) However, I could mount it manually with mount -t vfat /dev/sdc1 /mnt/sdc1 as you can see here: moose@pc07:~$ mount -l /dev/sda1 on / type ext4 (rw,errors=remount-ro,user_xattr) proc on /proc type proc (rw,noexec,nosuid,nodev) none on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) none on /dev type devtmpfs (rw,mode=0755) none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) none on /dev/shm type tmpfs (rw,nosuid,nodev) none on /var/run type tmpfs (rw,nosuid,mode=0755) none on /var/lock type tmpfs (rw,noexec,nosuid,nodev) none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755) binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev) gvfs-fuse-daemon on /home/moose/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=moose) /dev/sdc1 on /mnt/sdc1 type vfat (rw) edit: Another command: moose@pc07:~$ sudo blkid -o list device fs_type label mount point UUID ---------------------------------------------------------------------------------------------------------------------- /dev/sda1 ext4 / 45eb611b-517e-425b-8057-0391726cccd5 /dev/sda5 swap <swap> e9dc42f3-594c-4b62-874a-305eda5eed41 moose@pc07:~$ blkid -o list device fs_type label mount point UUID ---------------------------------------------------------------------------------------------------------------------- /dev/sda1 ext4 / 45eb611b-517e-425b-8057-0391726cccd5 /dev/sda5 swap <swap> e9dc42f3-594c-4b62-874a-305eda5eed41 /dev/sdc1 /mnt/sdc1 edit: another command: moose@pc07:~$ ls -l /dev/disk/by-uuid/ total 0 lrwxrwxrwx 1 root root 10 2012-09-30 09:31 45eb611b-517e-425b-8057-0391726cccd5 -> ../../sda1 lrwxrwxrwx 1 root root 10 2012-09-30 09:31 e9dc42f3-594c-4b62-874a-305eda5eed41 -> ../../sda5 Here is a link to a Launchpad question about this problem. But I would like it to mount automatically. What do I have to do?

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  • Find out which task is generating a lot of context switches on linux

    - by Gaks
    According to vmstat, my Linux server (2xCore2 Duo 2.5 GHz) is constantly doing around 20k context switches per second. # vmstat 3 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 2 0 7292 249472 82340 2291972 0 0 0 0 0 0 7 13 79 0 0 0 7292 251808 82344 2291968 0 0 0 184 24 20090 1 1 99 0 0 0 7292 251876 82344 2291968 0 0 0 83 17 20157 1 0 99 0 0 0 7292 251876 82344 2291968 0 0 0 73 12 20116 1 0 99 0 ... but uptime shows small load: load average: 0.01, 0.02, 0.01 and top doesn't show any process with high %CPU usage. How do I find out what exactly is generating those context switches? Which process/thread? I tried to analyze pidstat output: # pidstat -w 10 1 12:39:13 PID cswch/s nvcswch/s Command 12:39:23 1 0.20 0.00 init 12:39:23 4 0.20 0.00 ksoftirqd/0 12:39:23 7 1.60 0.00 events/0 12:39:23 8 1.50 0.00 events/1 12:39:23 89 0.50 0.00 kblockd/0 12:39:23 90 0.30 0.00 kblockd/1 12:39:23 995 0.40 0.00 kirqd 12:39:23 997 0.60 0.00 kjournald 12:39:23 1146 0.20 0.00 svscan 12:39:23 2162 5.00 0.00 kjournald 12:39:23 2526 0.20 2.00 postgres 12:39:23 2530 1.00 0.30 postgres 12:39:23 2534 5.00 3.20 postgres 12:39:23 2536 1.40 1.70 postgres 12:39:23 12061 10.59 0.90 postgres 12:39:23 14442 1.50 2.20 postgres 12:39:23 15416 0.20 0.00 monitor 12:39:23 17289 0.10 0.00 syslogd 12:39:23 21776 0.40 0.30 postgres 12:39:23 23638 0.10 0.00 screen 12:39:23 25153 1.00 0.00 sshd 12:39:23 25185 86.61 0.00 daemon1 12:39:23 25190 12.19 35.86 postgres 12:39:23 25295 2.00 0.00 screen 12:39:23 25743 9.99 0.00 daemon2 12:39:23 25747 1.10 3.00 postgres 12:39:23 26968 5.09 0.80 postgres 12:39:23 26969 5.00 0.00 postgres 12:39:23 26970 1.10 0.20 postgres 12:39:23 26971 17.98 1.80 postgres 12:39:23 27607 0.90 0.40 postgres 12:39:23 29338 4.30 0.00 screen 12:39:23 31247 4.10 23.58 postgres 12:39:23 31249 82.92 34.77 postgres 12:39:23 31484 0.20 0.00 pdflush 12:39:23 32097 0.10 0.00 pidstat Looks like some postgresql tasks are doing 10 context swiches per second, but it doesn't all sum up to 20k anyway. Any idea how to dig a little deeper for an answer?

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  • How to create VHD disk image from a Linux live system?

    - by Federico
    Once more, I have to resort at the experts here at SuperUser, as my other sources (mainly Google ;-)) didn't prove very helpful... So basically, I would like to create a VHD image of a physical disk to be archived/accessed/maybe even mounted in a virtual machine. Now, there are dozens of articles and tutorials on how to do that on the web, but none that meets exactly the conditions I would like to achieve: I would like the destination file to be a VHD image, as Windows 7 can mount it natively, even over the network and many other programs can use it (VirtualBox, ...) The disk I'm trying to image contains a Windows XP install, so in theory, I could use the disk2vhd utility, but I would like to find a solution that doesn't require booting that Windows XP install (ie keep the disk read-only) Thus I was searching for a solution involving some sort of live system (running from a USB stic or the network) However, all the solutions that I've came across either make use of disk2vhd or use the dd command under linux, which does a complete copy of the disk (ie even empty blocks) and does not output a VHD file. Is there a tool/program under Linux that can directly create a VHD file? Or is is possible to convert a raw disk image created using dd to a VHD file, without allocating space for the empty blocks? How would you proceed? As always, any advice or comment is highly appreciated!!

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  • CentOS 5.5 installation on disk image

    - by Dima
    Today, in order to install CentOS 5.5 I'm using kickstart script. I would like to install CentOS on different way: Create disk image (using dd command) Create filesystem on this disk image using mkfs.ext3 Install CentOS on this filesystem Make this disk image bootable (using grub-install) Copy the disk image to the physical hard disk (using dd command) I know to do all these items except 3. Is it possible to do it? If yes, how can I install CentOS on the disk image?

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  • limit linux background flush (dirty pages)

    - by korkman
    Background flushing in linux happens when either too much written data is pending (adjustable via /proc/sys/vm/dirty_background_ratio) or a timeout for pending writes is reached (/proc/sys/vm/dirty_expire_centisecs). Unless another limit is being hit (/proc/sys/vm/dirty_ratio), more written data may be cached. Further writes will block. In theory, this should create a background process writing out dirty pages without disturbing other processes. In practice, it does disturb any process doing uncached reading or synchronous writing. Badly. This is because the background flush actually writes at 100% device speed and any other device requests at this time will be delayed (because all queues and write-caches on the road are filled). Is there any way to limit the amount of requests per second the flushing process performs, or otherwise effectively prioritize other device I/O?

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  • Changing memory allocator to Jemalloc Centos 6

    - by Brian Lovett
    After reading this blog post about the impact of memory allocators like jemalloc on highly threaded applications, I wanted to test things on a larger scale on some of our cluster of servers. We run sphinx, and apache using threads, and on 24 core machines. Installing jemalloc was simple enough. We are running Centos 6, so yum install jemalloc jemalloc-devel did the trick. My question is, how do we change everything on the system over to using jemalloc instead of the default malloc built into Centos. Research pointed me at this as a potential option: LD_PRELOAD=$LD_PRELOAD:/usr/lib64/libjemalloc.so.1 Would this be sufficient to get everything using jemalloc?

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  • Benchmark for website speed optimization

    - by gowri
    I working on website speed optimization. I mostly used 3 tools for analyzing speed of optimization. Speed analyzing Tools: Google pagespeed tool Yslow Firefox extenstion Web Page Performance Test I am measuring performance using above tool and benchmark result as below like before and after. Before optimization : Google PageSpeed Insights score : 53/100 Web Page Performance Test : 55/100 (First View : 10.710s, Repeat view : 6.387s ) Yahoo Overall performance score : 68 Stage 1 After optimization : Google PageSpeed Insights score : 88/100 Web Page Performance Test : 88/100 (First View : 6.733s, Repeat view : 1.908s ) Yahoo Overall performance score : 80 My question is ? Am i doing correct way ? What is the best way of benchmark for speed optimization ? Is there any standard ? Is there any much better tool for analyzing speed ?

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  • ATG Live Webcast March 21 Reminder: Network, WAN, and PC Performance Tuning (Performance Series Part 3 of 3)

    - by BillSawyer
    A quick reminder about tomorrow's webcast:  Andy Tremayne, Senior Architect, Applications Performance, and co-author of Oracle Applications Performance Tuning Handbook from Oracle Press, and Uday Moogala, Senior Principal Engineer, Applications Performance, will discuss network performance for E-Business Suite. Andy and Uday will cover tuning the client and tuning the network. They will share real-life examples of network performance, and show you tools and techniques that you can use to estimate or simulate performance on your own network.The agenda for the Performance Tuning - Part 3 of 3 webcast includes the following topics: Tuning the Client Tuning the Network Date:               Thursday, March 21, 2012Time:              8:00 AM - 9:00 AM Pacific Standard TimePresenters:  Andy Tremayne, Senior Architect, Applications Performance                        Uday Moogala, Senior Principal Engineer, Applications PerformanceWebcast Registration Link (Preregistration is optional but encouraged)To hear the audio feed:   Domestic Participant Dial-In Number:           877-697-8128    International Participant Dial-In Number:      706-634-9568    Additional International Dial-In Numbers Link:    Dial-In Passcode:                                              99341To see the presentation:    The Direct Access Web Conference details are:    Website URL: https://ouweb.webex.com    Meeting Number:  591264961If you miss the webcast, or you have missed any webcast, don't worry -- we'll post links to the recording as soon as it's available from Oracle University.  You can monitor this blog for pointers to the replay. And, you can find our archive of our past webcasts and training here.

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  • Disallow user from decrypting the startup disk

    - by Blacklight Shining
    When you enable FileVault's full-disk encryption, it asks for the password of each account on the system to allow every user to decrypt the disk. You can simply choose not to have a user enter their password, and they will not be able to decrypt the disk. However, if you create an account after enabling disk encryption, the user is automatically allowed to decrypt the disk. How do I disallow a user from decrypting the startup disk?

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  • Ubuntu 12.04.1 LTS USB not being detected after formatting with Startup Disk Creator

    - by Zach
    sudo fdisk -l lists the drive, however, I cannot find it in the file explorer. Disk /dev/sda: 250.1 GB, 250059350016 bytes 255 heads, 63 sectors/track, 30401 cylinders, total 488397168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000d871e Device Boot Start End Blocks Id System /dev/sda1 * 2048 486322175 243160064 83 Linux /dev/sda2 486324222 488396799 1036289 5 Extended /dev/sda5 486324224 488396799 1036288 82 Linux swap / Solaris Disk /dev/sdb: 8195 MB, 8195480064 bytes 253 heads, 62 sectors/track, 1020 cylinders, total 16006797 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00027ae4 Device Boot Start End Blocks Id System /dev/sdb1 * 62 15999719 M 7999829 c W95 FAT32 (LBA) Manually mounting it produces this error message :~$ sudo mount -t vfat /dev/sdb1 /media/external -ouiduid=1000,gid=1000,utf8,dmask=027,fmask=137 mount: wrong fs type, bad option, bad superblock on /dev/sdb1, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so Is the usb toast?

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  • Why MySQL sat for 2 minutes doing nothing?

    - by Alex R
    This was a one-time thing, not reproducible... But I saved the show innodb status output. Can anybody tell what's going on here? The simple insert took almost 3 minutes to complete. | InnoDB | | ===================================== 110201 15:58:10 INNODB MONITOR OUTPUT ===================================== Per second averages calculated from the last 34 seconds ---------- SEMAPHORES ---------- OS WAIT ARRAY INFO: reservation count 11963, signal count 11766 --Thread 1824 has waited at .\btr\btr0cur.c line 443 for 118.00 seconds the sema phore: S-lock on RW-latch at 09D6453C created in file .\buf\buf0buf.c line 550 a writer (thread id 1824) has reserved it in mode wait exclusive number of readers 1, waiters flag 1 Last time read locked in file .\buf\buf0flu.c line 599 Last time write locked in file .\btr\btr0cur.c line 443 Mutex spin waits 0, rounds 527817, OS waits 7133 RW-shared spins 2532, OS waits 1226; RW-excl spins 1652, OS waits 1118 ------------ TRANSACTIONS ------------ Trx id counter 0 95830 Purge done for trx's n:o < 0 95814 undo n:o < 0 0 History list length 11 LIST OF TRANSACTIONS FOR EACH SESSION: ---TRANSACTION 0 0, not started, OS thread id 3704 MySQL thread id 551, query id 2702112 localhost 127.0.0.1 root show innodb status ---TRANSACTION 0 95829, not started, OS thread id 3132 MySQL thread id 534, query id 2702020 localhost 127.0.0.1 root ---TRANSACTION 0 95828, not started, OS thread id 3152 MySQL thread id 527, query id 2701973 localhost 127.0.0.1 root ---TRANSACTION 0 95827, ACTIVE 118 sec, OS thread id 1824 inserting, thread decl ared inside InnoDB 500 mysql tables in use 1, locked 1 1 lock struct(s), heap size 320, 0 row lock(s) MySQL thread id 526, query id 2701972 localhost 127.0.0.1 root update INSERT INTO log_searchcriteria (userid,search_criteria,date,search_type) VALUES ( NAME_CONST('userid',NULL), NAME_CONST('search_criteria',_latin1' SELECT SQL_C ALC_FOUND_ROWS idx_search.CTCX_LATITUDE, idx_search.CTCX_LONGITUDE, idx_search.b uilding_id, idx_search.LN_LIST_NUMBER, idx_search.LP_LIST_PRICE, idx_search.HSN_ ADRESS_HOUSE_NUMBER, idx_search.STR_ADDRESS_STREET, idx_search.CP_ADDRESS_COMPAS S_POINT, idx_search.UN_UNIT, idx_search.CIT_CITY, idx_search.ZP_ZIP_CODE, idx_se arch.AR_AREA_NAME, idx_search.BR_BEDROOMS, idx_search.BTH_BATHS, idx_search.ST_S TATUS, idx_search.CTCX_STYLE_TYPE, idx_s -------- FILE I/O -------- I/O thread 0 state: wait Windows aio (insert buffer thread) I/O thread 1 state: wait Windows aio (log thread) I/O thread 2 state: wait Windows aio (read thread) I/O thread 3 state: wait Windows aio (write thread) Pending normal aio reads: 0, aio writes: 1, ibuf aio reads: 0, log i/o's: 0, sync i/o's: 0 Pending flushes (fsync) log: 0; buffer pool: 0 151006 OS file reads, 120758 OS file writes, 6844 OS fsyncs 0.00 reads/s, 0 avg bytes/read, 0.00 writes/s, 0.00 fsyncs/s ------------------------------------- INSERT BUFFER AND ADAPTIVE HASH INDEX ------------------------------------- Ibuf: size 1, free list len 5, seg size 7, 24664 inserts, 24664 merged recs, 4612 merges Hash table size 553253, node heap has 629 buffer(s) 0.00 hash searches/s, 0.00 non-hash searches/s --- LOG --- Log sequence number 5 2318193115 Log flushed up to 5 2318193115 Last checkpoint at 5 2318129891 0 pending log writes, 0 pending chkp writes 3036 log i/o's done, 0.00 log i/o's/second ---------------------- BUFFER POOL AND MEMORY ---------------------- Total memory allocated 213459462; in additional pool allocated 1720192 Dictionary memory allocated 240416 Buffer pool size 8192 Free buffers 0 Database pages 7563 Modified db pages 18 Pending reads 0 Pending writes: LRU 0, flush list 18, single page 0 Pages read 150973, created 28788, written 115137 0.00 reads/s, 0.00 creates/s, 0.00 writes/s No buffer pool page gets since the last printout -------------- ROW OPERATIONS -------------- 1 queries inside InnoDB, 0 queries in queue 1 read views open inside InnoDB Main thread id 2992, state: flushing buffer pool pages Number of rows inserted 794294, updated 89203, deleted 13698, read 1453084305 0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s ---------------------------- END OF INNODB MONITOR OUTPUT ============================ Thanks

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