Today I noticed that one of storage group on my Exchange Server 2007 was dismounted.
I tried to mount database manually but It failed.
In Event Viewer I saw this error:
Event Type: Error
Event Source: MSExchange System Attendant Mailbox
Event Category: General
Event ID: 4001
Date: 2008-09-05
Time: 12:33:22
User: N/A
Computer: …
Description:
A transient failure has occurred. The problem may resolve itself in a while. The service will retry in 56 seconds. Diagnostic information:

Cannot open mailbox /o=bonso/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=…/cn=Microsoft System Attendant.
Microsoft.Exchange.Data.Storage.ConnectionFailedTransientException: Cannot open mailbox /o=bonso/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=….cn=Microsoft System Attendant. —> Microsoft.Mapi.MapiExceptionLogonFailed: MapiExceptionLogonFailed: Unable to open message store. (hr=0×80040111, ec=-2147221231)
Diagnostic context:
Lid: 18969 EcDoRpcExt2 called [length=239]
Lid: 27161 EcDoRpcExt2 returned [ec=0x0][length=112][latency=0]
Lid: 23226 — ROP Parse Start —
Lid: 27962 ROP: ropLogon [254]
Lid: 17082 ROP Error: 0×80040111
Lid: 26937
Lid: 21921 StoreEc: 0×80040111
Lid: 27962 ROP: ropExtendedError [250]
Lid: 1494 —- Remote Context Beg —-
Lid: 26426 ROP: ropLogon [254]
Lid: 22970
Lid: 8620 StoreEc: 0×80040111
Lid: 10786 dwParam: 0×0 Msg: BONSO-DC1
Lid: 1750 —- Remote Context End —-
Lid: 26849
Lid: 21817 ROP Failure: 0×80040111
Lid: 26297
Lid: 16585 StoreEc: 0×80040111
Lid: 32441
Lid: 1706 StoreEc: 0×80040111
Lid: 24761
Lid: 20665 StoreEc: 0×80040111
Lid: 25785
Lid: 29881 StoreEc: 0×80040111

In Services I noticed that ??oMicrosoft Exchange Information Store??? is stopped.
I started this service manually and everything started.
I tried to mount database but it failed again.
Hmmm ?.
Ok ? I tried to move ??oStorage Group Path??? to other location, operation completed successful.
And mounted storage group ? database started ? uffff