before you start – this will only work if your photos actually exist on your device but do not show up in in the camera roll. you can verify that photos exist on your device by looking graph at the bottom of iTunes and by checking your device for the actual picture files. if you post comments about having problems but don’t mention that you haven’t verified that your photos are still available on your device, i’m sorry but i won’t be able to help you.

so i decided to upgrade to the new iOS 4 on my iphone 3gs to see what it is all about. everything went smoothly. i installed itunes 9.2, downloaded the new firmware, asked my phone to do a restore using the new firmware and then had it restore my latest backup of info. everything seemed perfect after syncing with itunes but then i went into my camera roll and noticed i had no pictures! in itunes, it showed over 1 GB worth of pictures so why were they not showing up? i searched online for a little while i didn’t really come up with much at first. many different solutions: do a backup, sync, reboot, etc but nothing worked. then i came across this discussion on the apple forums. i have slightly modified the steps. if you use windows or osx, you can download iphone explorer and follow these steps:

these steps are out of date.  see below for updated steps.
1.) connect your iphone using the usb cable
2.) launch iphone explorer
3.) backup and then delete the following files (backup instructions):
     /DCIM/.MISC/Info.plist
     /PhotoData/Photos.sqlite
     /PhotoData/PhotosAux.sqlite
4.) reboot your iphone

a recent update to iphone explorer may have changed the folder paths. if you don’t see the folders mentioned, try the following:

1.) connect your iphone using the usb cable
2.) launch iphone explorer
3.) backup and then delete the following files (backup instructions):
     /Media/DCIM/.MISC/Info.plist
     /Media/PhotoData/MISC/DCIM_APPLE.plist
     /Media/PhotoData/Photos.sqlite (or /PhotoData/Photos.sqlite)
     /Media/PhotoData/PhotosAux.sqlite (or /PhotoData/PhotosAux.sqlite)
4.) reboot your iphone

note: if you don’t have the file PhotosAux.sqlite, that’s not a problem. It is a database of the location of where photos were taken which is extracted from the EXIF data of the pictures. i would guess that it is uses by the Places feature in the camera roll.

if your phone is jailbroken and you are in ‘root’ view in iphone explorer, these instructions & file locations should work:

1.) connect your iphone using the usb cable
2.) launch iphone explorer
3.) backup and then delete the following files:
     /private/var/mobile/Media/PhotoData/.MISC/Info.plist
     /private/var/mobile/Media/PhotoData/MISC/DCIM_APPLE.plist
     /private/var/mobile/Media/PhotoData/Photos.sqlite
     /private/var/mobile/Media/PhotoData/PhotosAux.sqlite
4.) reboot your iphone

if you have linux, you shouldn’t need anything as long as you can mount your iphone as a device and delete the files listed above. i used debian (squeeze) to access the files as it automatically mounts my iphone when i plug it in. i just enabled ‘view hidden files’ and i could access the files to delete.

once you have done that, just open your camera roll and it should re-index all of your photos!

*edit: as Phil has pointed out in the comments, if the file ‘/DCIM/.MISC/Info.plist’ does not exist or if you can’t find the folder ‘/DCIM/.MISC’, just skip past that file and follow the rest of the directions and it should still restore your photos in the camera roll.

*edit: has anyone had this happen with the latest update to iOS 5? i am curious whether or not it is happening again with the latest iOS. if it is, please let me know in the comments. thanks!

users of comcast have recently reported that they are no longer able to relay their mail using ‘smtp.comcast.net’ over port 25. comcast had previously allowed port 25 traffic to be relayed inside their network when going to ‘smtp.comcast.net’. unfortunately they are no longer allowing this which is a major problem for me any anyone who is using comcast’s smtp server as a smtp connector in exchange.

the easiest way to get around this problem is by changing the port in which your exchange server sends and receives email. in my case, i decided to change mine to port 587 which is what comcast is using as the chances of them blocking that port is a bit slimmer than before. in order to change this, i had to modify the port setting in two places (for each smtp server i had running). start by opening Exchange System Manager. from there, go to Administrative Groups > First Administrative Group > Servers > [servername] > Protocols > SMTP > then right click on Default SMTP Virtual Server and choose Properties.

then go to Advanced > Edit > then change the TCP port to the new port (in this case, 587). click OK twice and then click on the Delivery tab > Outbound connections. change TCP port from 25 to the new value. then choose OK twice which will return you to the Exchange System Manager. if you have another exchange server in your organization, you will need to perform the same steps for the other servers. once you have done this, you will need to restart the Default SMTP Virtual Server(s) for the changes to take effect (or a restart would work as well).

i use port forwarding on my router which i have setup to route incoming port 25 traffic to port 587. even though port 25 is blocked, it enables me to connect using the default server port of 25 from inside my network. i also use a no-ip service for incoming smtp redirection which will redirects all of my mail traffic to a high port so it will not be blocked by my ISP. i had to configure the port forwarding on my router to point to port 587 internally instead of port 25 while still listening on the high port number as before. this allows my email to continue to send and receive properly despite having port 25 blocked by my ISP.

at home, i have five virtual machines that i rely on heavily for my day-to-day operations. i have two windows server 2008 domain controllers, two windows server 2003 servers running exchange 2003 and one windows server 2008 computer i use for remote desktop and management of services. some of these services can provide a fair load on my server and i was starting to see the impact, especially from my win2k8 vms. it seems that there are a number of optimizations that are not enabled by default in vmware server. i searched far and wide through vmware kb docs as well as blogs and web forums and came up with the following optimizations:

force virtual machines to run in shared memory (in ram)
inside ‘/etc/vmware/config’ lies the default config for vmware. add the following lines at the end:

MemTrimRate = "0"
mainMem.useNamedFile = "FALSE"
sched.mem.pshare.enable = "FALSE"
tmpDirectory="/dev/shm"

this will ensure that virtual machines actually store their virtual memory on /dev/shm. /dev/shm is a location that most linux distributions use for shared memory that is located directly on ram (think of a ramdisk). you will want to make sure that your host makes uses of /dev/shm as seen below:

root@athena:~# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/md0               67G  7.3G   56G  12% /
tmpfs                 4.0G     0  4.0G   0% /lib/init/rw
udev                   10M  972K  9.1M  10% /dev
tmpfs                 8.0G  5.1G  3.0G  64% /dev/shm
/dev/md2              917G  665G  207G  77% /media/md2
/dev/md3              917G  556G  315G  64% /media/md3

the text in italics above is what you are looking for. by default, most distros will not allocate that much space for shared memory. however, you can specify the size in the file ‘/etc/default/tmpfs’:

# SHM_SIZE sets the maximum size (in bytes) that the /dev/shm tmpfs can use.
# If this is not set then the size defaults to the value of TMPFS_SIZE
# if that is set; otherwise to the kernel's default.
#
# The size will be rounded down to a multiple of the page size, 4096 bytes.
SHM_SIZE=8G

by default the variable seen above will be blank (ie – ‘SHM_SIZE=’). i set mine to 8GB because i have 8GB of ram in my server. the great thing about using shared memory is that if you happen to actually fill up your system’s ram, it will start using swap space instead of just running out of room.

next, i added a few lines to the file ‘/etc/sysctl.conf’:

vm.swappiness = 0
vm.overcommit_memory = 1
vm.dirty_background_ratio = 5
vm.dirty_ratio = 10
vm.dirty_expire_centisecs = 1000

it is my understanding that these are meant to help prevent vmware from using the swap file unnecessarily.

last but not least, i needed to do a little bit of optimization of my file system. my server uses software raid 1 with an ext3 file system so write performance isn’t amazing but to speed things up, i changed a few of the mount options in my ‘/etc/fstab’:

 /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>          <options>                       <dump>  <pass>
proc            /proc           proc            defaults                        0       0
/dev/md0        /               ext3            errors=remount-ro,relatime      0       1
/dev/md1        none            swap            sw                              0       0
/dev/scd0       /media/cdrom0   udf,iso9660     user,noauto                     0       0
/dev/md2        /media/md2      ext3            defaults,noatime,nodiratime     0       2
/dev/md3        /media/md3      ext3            defaults,noatime,nodiratime     0       2

i added the ‘noatime,nodiratime’ options so that write times are not constantly being recorded causing excessive delays.

these settings seem to make my virtual machines run smoother and boot much faster.