This Page Intentionally Left Blank!

So, the recent inactivity is not just because I’m a lazy bastard, but that doesn’t help, either.

My life has been turned upside down yet again this year, and until I figure out what exactly is happening, I figured it was probably best to just keep quiet. On the bright side, being lost can have the advantage of new and interesting experiences … if you choose to look around during the ride.

All of that notwithstanding, I miss the hell out of my family and friends that I have had to leave behind for the duration.

Hopefully, life becomes a bit more clear in the near future!

Spiffy Webapps From 37signals

I suppose these would be “Web 2.0″ apps?  Either way, the webapps from 37signals seem pretty cool.

They currently offer:

• Basecamp - Project management and collaboration - Collaborate with your team and clients. Schedules, tasks, files, messages, and more.
• Highrise - Online contact manager and simple CRM - Keep track of who your business talks to, what was said, and what to do next.
• Backpack - Intranet, group calendar, organizer – Share info, schedules, documents, and to-dos across your company, group, or organization.
• Campfire - Real-time group chat for business - It’s like instant messaging, but optimized for groups. Especially great for remote teams.

All are online webapps with lots of AJAX and other goodies … subscription model with various levels.

Campfire looks interesting, but we are currently using Skype until we get our Jabber server happy again.

Backpack looks like something we could use, especially since our entire team is diversely located … well, *I’m* diversely located, and the rest are in one region.  :)

Highrise may be of interest to our Sales folks … I’m having them look at it now.

Basecamp could be very useful if we fire off some of the larger development projects we are considering.

In any case, the company has been around for a bit and seems to be improving their offerings, so keep an eye on them.

DISCLAIMER:  I have *no* affiliation with 37signals, and I’m not even a customer at this time, but it does look interesting and worth further investigation and discussion within our team.

Expanding a Linux LVM PV and underlying RAID5

Background

Normally, we run our servers with RAID1 with a pair of disks added at a time. Since we also use DRBD on top of our LVM LVs, we have 3 servers in play (3-way DRBD replication) — this means adding new disks in groups of 6, which is sort of spendy.

So, with our new servers, we are looking into switching out the RAID1s (grouped into a single VG) to a single RAID5 under the LVM PV (in a single VG). Linux RAID5s can be expanded on the fly, this lets us grow the data disk by adding only 1 disk at a time (3 across the 3 servers). The bulk of the application servers are not really I/O intensive, so we’re not really worried about the RAID5 performance hit.

Here’s the setup on our test of this process:

• Ubuntu 8.04 LTS Server
• AMD 64 x2 5600+ with 8GB
• 3 x 1TB SATA2 drives, 2 x 750GB SATA2 drives
• Xen’ified 2.6.18 kernel with Xen 3.3.1-rc4
• Linux RAID, LVM2, etc, etc.

We configured the partitions on the data disks as 2GB partitions, just so the sync doesn’t take *forever*.

Disk /dev/sde: 750.1 GB, 750156374016 bytes
255 heads, 63 sectors/track, 91201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00046fcd

   Device Boot      Start         End      Blocks   Id  System
/dev/sde1               1        1217     9775521   fd  Linux raid autodetect
/dev/sde2            1218        1704     3911827+  82  Linux swap / Solaris
/dev/sde3            1705        1946     1959930   fd  Linux raid autodetect

The initial RAID 5 configuration:

md1 : active raid5 sda3[0] sdc3[2] sdb3[1]
      3919616 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]

LVM configuration:

root@xen-80-31:~# pvdisplay /dev/md1
  --- Physical volume ---
  PV Name               /dev/md1
  VG Name               testvg
  PV Size               3.74 GB / not usable 3.75 MB
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              956
  Free PE               956
  Allocated PE          0
  PV UUID               h6qBlQ-RCy3-YeE9-zQXw-j1oa-bg8K-2JULo1

root@xen-80-31:~# vgdisplay testvg
  --- Volume group ---
  VG Name               testvg
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  1
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               3.73 GB
  PE Size               4.00 MB
  Total PE              956
  Alloc PE / Size       0 / 0
  Free  PE / Size       956 / 3.73 GB
  VG UUID               iOVFKf-8iSV-k1VK-G37u-Ivns-9uqx-vZCduc

Process to expand the data device

Initial RAID5 configuration:

root@xen-80-31:~# mdadm --detail /dev/md1
/dev/md1:
        Version : 00.90.03
  Creation Time : Thu Jan  8 04:33:16 2009
     Raid Level : raid5
     Array Size : 3919616 (3.74 GiB 4.01 GB)
  Used Dev Size : 1959808 (1914.20 MiB 2006.84 MB)
   Raid Devices : 3
  Total Devices : 3
Preferred Minor : 1
    Persistence : Superblock is persistent

    Update Time : Thu Jan  8 17:52:46 2009
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 64K

           UUID : 8fd9e7d9:0dae82af:b836248b:2f509f91
         Events : 0.4

    Number   Major   Minor   RaidDevice State
       0       8        3        0      active sync   /dev/sda3
       1       8       19        1      active sync   /dev/sdb3
       2       8       35        2      active sync   /dev/sdc3

Add the new 2GB device to the RAID5 — it will show up as a “spare” device initially:

root@xen-80-31:~# mdadm --add /dev/md1 /dev/sdd3
mdadm: added /dev/sdd3
root@xen-80-31:~# mdadm --detail /dev/md1
/dev/md1:
        Version : 00.90.03
  Creation Time : Thu Jan  8 04:33:16 2009
     Raid Level : raid5
     Array Size : 3919616 (3.74 GiB 4.01 GB)
  Used Dev Size : 1959808 (1914.20 MiB 2006.84 MB)
   Raid Devices : 3
  Total Devices : 4
Preferred Minor : 1
    Persistence : Superblock is persistent

    Update Time : Thu Jan  8 17:52:46 2009
          State : clean
 Active Devices : 3
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 1

         Layout : left-symmetric
     Chunk Size : 64K

           UUID : 8fd9e7d9:0dae82af:b836248b:2f509f91
         Events : 0.4

    Number   Major   Minor   RaidDevice State
       0       8        3        0      active sync   /dev/sda3
       1       8       19        1      active sync   /dev/sdb3
       2       8       35        2      active sync   /dev/sdc3

       3       8       51        -      spare   /dev/sdd3

Grow the RAID5 to include the new device:

root@xen-80-31:~# lvs
  LV    VG     Attr   LSize Origin Snap%  Move Log Copy%
  test1 testvg -wi-a- 1.00G
root@xen-80-31:~# mdadm --grow /dev/md1 --raid-devices=4
mdadm: Need to backup 384K of critical section..
mdadm: ... critical section passed.

/proc/mdstat:

md1 : active raid5 sdd3[3] sda3[0] sdc3[2] sdb3[1]
      3919616 blocks super 0.91 level 5, 64k chunk, algorithm 2 [4/4] [UUUU]
      [=>...................]  reshape =  7.9% (156192/1959808) finish=1.3min speed=22313K/sec

While the reshape is running, the VG is still active:

root@xen-80-31:~# lvcreate -L 1g -n test2 testvg
  Logical volume "test2" created
root@xen-80-31:~# lvs
  LV    VG     Attr   LSize Origin Snap%  Move Log Copy%
  test1 testvg -wi-a- 1.00G
  test2 testvg -wi-a- 1.00G

After reshaping complete:

root@xen-80-31:~# mdadm --detail /dev/md1
/dev/md1:
        Version : 00.90.03
  Creation Time : Thu Jan  8 04:33:16 2009
     Raid Level : raid5
     Array Size : 5879424 (5.61 GiB 6.02 GB)
  Used Dev Size : 1959808 (1914.20 MiB 2006.84 MB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 1
    Persistence : Superblock is persistent

    Update Time : Thu Jan  8 18:44:32 2009
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 64K

           UUID : 8fd9e7d9:0dae82af:b836248b:2f509f91
         Events : 0.1336

    Number   Major   Minor   RaidDevice State
       0       8        3        0      active sync   /dev/sda3
       1       8       19        1      active sync   /dev/sdb3
       2       8       35        2      active sync   /dev/sdc3
       3       8       51        3      active sync   /dev/sdd3

The new space is not reflected yet in the PV or VG – grow the PV:

root@xen-80-31:~# pvresize /dev/md1
  Physical volume "/dev/md1" changed
  1 physical volume(s) resized / 0 physical volume(s) not resized
root@xen-80-31:~# pvdisplay
  --- Physical volume ---
  PV Name               /dev/md1
  VG Name               testvg
  PV Size               5.61 GB / not usable 1.44 MB
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              1435
  Free PE               923
  Allocated PE          512
  PV UUID               h6qBlQ-RCy3-YeE9-zQXw-j1oa-bg8K-2JULo1

root@xen-80-31:~# vgdisplay
  --- Volume group ---
  VG Name               testvg
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  4
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               5.61 GB
  PE Size               4.00 MB
  Total PE              1435
  Alloc PE / Size       512 / 2.00 GB
  Free  PE / Size       923 / 3.61 GB
  VG UUID               iOVFKf-8iSV-k1VK-G37u-Ivns-9uqx-vZCduc

In another test, growing 3 x 200GB partitions by 1 more 200GB partition on our system took around 150 minutes, so the reshaping process is not super speedy. Even though our test showed that you can still perform I/O against the back end data store (RAID5) while it is reshaping, it would probably be best to keep I/O to a minimum.

UPDATE: We repeated the test with 3 x 700GB partitions and added a 4th 700GB partition — reshaping time took about 8.5h with no external I/O performed to the LVM/RAID5 device.

This Artist Is Going Big Time!

My sister has been doing artsy, craftsy, musicy stuff forever, and she realized a few years ago that it is important enough to her to really let it come out and shine.

She recently had the opportunity to do an exhibit of her work in Jacksonville, FL’s Artwalk 2008 — her first *big* exhibit!  See here and here for some details from her blog.

She has prints of her work for sale as well as *some* of the originals, so contact her for more details.  She even has a hook-up if you want some of her stuff on a t-shirt, hoodie, mug, bag, etc here!

Finally, she even has her new book up and available at Amazon.  Poetry and observations from her life experiences — truely interesting and insightful to her life and inspirations.

She even has some of her music online somewhere, but I’ll have to find that for another post.  Her boyfriend, a friend, and her are gigging somewhere in the near future, so maybe they’ll get a recording of that, too (hint hint).