FILE SYSTEM NOT AVAILABLE

[quant36]

We are running Windows and three weeks ago we replaced our main network drive with a new one. Ever since we did that, our virtual server whose job is to kicks off a few APL processes after hours, started running into "FILE SYSTEM NOT AVAILABLE" error several times a week as it reads/writes to our new network storage. The after-hours network traffic in our office is very light and we eliminated all anti-virus/backup operations during the server's APL jobs, but the problem still persists.

According to Daylog APL Version 13.1 User Guide (page 286), "In a PC network, or in a single-processor Unix environment, if the FSCB file is missing or inaccessible (restricted access permissions) the report FILE SYSTEM NOT AVAILABLE (Error code 28) will be given. The same error will occur under NFS if the aplfscb "daemon" is not running.”

Has anyone encountered this error before and could share solutions?
Any links that would shed some light on what aplfscb daemon is?
Actually, any thoughts are welcomed at this point since standard monitoring tools haven't shown anything unusual.

Thanks,

Andrew Chou
Jennison Associates LLC

[Vince|Dyalog]

We are corresponding with Andrew via email as well.

I have moved this topic to the Windows forum.

Regards,

Vince

[quant36]

The primary cause of "File System Not Available" error, in our case, turned out to be Opportunistic locking, or Oplocks, as it is commonly known.

Oplocks is a unique Windows locking feature that enhances the perceived performance of applications on a networked client. It is most effective in single user, or one-user-at-a-time, environments (e.g. home directories). Basically, oplocks is a toggle for client-side data caching and serves as a notification mechanism for writing the local file back to the networked storage disk.

Oplocks, however, is not reliable in "multi-user database on a share" environment, in file sharing mechanisms (e.g. NFS), across a WAN, on slow/unreliable networks, or with Process Data Management (PDM) applications. In all of these cases, disabling oplocks is strongly recommended.

The following article describes OPLOCKS in more detail:
https://www.samba.org/samba/docs/man/Sa ... cking.html

I would like to take this opportunity to thank Dyalog, especially Andy and Vince, for their time and help in resolving this issue.

Thank you,
Andrew Chou
Jennison Associates LLC

[Vince|Dyalog]

Hi Andrew,

We are very glad that you have found the primary cause of this network issue.

Thanks for updating this topic and sharing your experience.

It will help us and other users.

Regards,

Vince

[AndyS|Dyalog]

.. and I have just added a note about oplocks to a couple of places in the 16.0 documentation.