Question : Waittype PAGEIOLATCH_SH with a large waittime is degrading system performance

This morning system performance was degrading as the number of the system processes was exploding. Normally I have about 20 processes running on a database (master..sysprocesses), but in one hour it grew to 200. Wheb I checked the table I saw this:

spid   wait       waittime    lastwaittype       trans    status
54     0x0422   262937   PAGEIOLATCH_SH   0        sleeping   (about 140 of these)
61     0x0422    28304    PAGEIOLATCH_SH   2        sleeping   (about 20 of these)
66     0x0000            0   PAGELATCH_UP      2         runnable (2 of these)
88     0x0000            0   PAGEIOLATCH_EX   2         runnable (1 of these)
101   0x0424     28187   PAGEIOLATCH_EX   2         sleeping  (4 of these)

I restarted the server and the problem was solved. All the processes came from the .Net SqlClient Data Provider. Some of my SQL jobs got the following warning during that hour:

Executed as user: NETMATCH5\sqlserver. Time-out occurred while waiting for buffer latch type 2 for page (1:147380), database ID 10. [SQLSTATE 42000] (Error 845).  The step failed.

My questions are:
1. What do the waittype 0x0422 and 0x0424 mean? I looked on internet but could not find a list of waittypes.
2. What could the reason be, disk IO too much stress?

Regards, Lex van de Pol

Answer : Waittype PAGEIOLATCH_SH with a large waittime is degrading system performance

I had similar errors.  While pondering their significance for a day, the RAID controller card died.  I don't know if this was coincidence or the errors were trying to warn me badness was about to happen.