What is the meaning of the message: <drive not available: formatting> from the Solaris [TM] format(1m) utility?

Asset ID:	1-71-1005475.1
Update Date:	2012-09-14
Keywords:

Solution Type Technical Instruction Sure

Solution 1005475.1 : What is the meaning of the message: from the Solaris [TM] format(1m) utility?

Applies to:

Sun Storage T3+ Array - Version Not Applicable and later
Sun Disk, 500 GB, 7200 rpm, SATA - Version Not Applicable and later
Sun Storage T3 Array - Version Not Applicable and later
Sun Flash F5100 Array - Version Not Applicable and later
Exadata Database Machine X2-2 Hardware - Version Not Applicable and later
All Platforms

Goal

Description

This message is sometimes reported for a disk when running the Solaris [TM] format(1m) utility, e.g.:

# format


Searching for disks...done



AVAILABLE DISK SELECTIONS:


0. c0t0d0 <drive not available: formatting>


/sbus@6,0/SUNW,socal@d,10000/sf@0,0/ssd@w210000163787753a,0

What does it mean?

Fix

Steps to Follow

To understand this message requires explaining some history...

With older disk drives which did not perform automatic bad block reallocation, the Solaris format(1m) utility was used to mark bad blocks and to format disk drives to avoid using those bad blocks.

With modern disk drives, the format(1m) utility is only very, very rarely used to actually perform a format of a disk drive, mainly because modern disk drives perform auto-reallocation of bad blocks (and therefore automatically "retire" that defective piece of media) upon certain read or write errors, without the disk drive needing to be completely re-formatted.

Due to the length of time which a disk drive requires to perform a "Format Unit" command (e.g. some hours, depending on the disk drive capacity and performance), the format(1m) utility is designed to show when a disk drive is formatting, and to allow the user to perform actions against other disk drives during that time.

This is why the <drive not available: formatting> message was introduced, to indicate which disks were not available for the format(1m) utility to use, at that particular time.

During formatting (e.g. while it is executing a "Format Unit" command), a disk drive will respond to an "Inquiry" command, but will return an error for almost every other command that is sent to it, including a "Read" command. Typically it will return a "check condition" to the host, with sense key 0x2 (not ready), ASC 0x4, ASCQ 0x4 (logical unit not ready, format in progress).

The format(1m) utility will therefore show the message:

<drive not available: formatting>

when the disk drive has responded to an "Inquiry" command, but has returned an error when the utility then attempts to read the label from LBA 0 on the disk. Note: The contents of the disk label are not interpreted at this stage - format(1m) just checks that the "Read" command to LBA 0 is successful. This successful "Inquiry" command, followed by an unsuccessful "Read" command, is the behavior of a disk drive which is in the process of formatting.

However, if the user has not started to format a disk drive, and sees this <drive not available: formatting> message, then it is possible that the disk drive is faulty.

The typical cause is that the disk drive is reporting a "not ready" sense key due to an internal fault. Disk drives in that faulty condition often respond to an "Inquiry", but are unable to respond successfully to a "Read" command - which is very similar behavior to a disk drive while it is performing a "Format Unit" command.

Other less likely causes could include:

The disk drive is reporting an unrecoverable read error on LBA 0; or
The disk drive has just been power-cycled or reset, it is in the process of becoming ready, and will become ready (and able to respond to a "Read" command) within a few seconds.

The format(1m) utility sends all commands to disk drives with the USCSI_SILENT flag set, so no error messages are logged in /var/adm/messages with the default value of sd_error_level (ssd_error_level when using the ssd driver) even if errors do occur. This is to prevent customer concern when some expected errors occur, but this makes it difficult to find the exact cause of the <drive not available: formatting> message.

In some cases, running:

# format -Mm

may be helpful as this reports additional messages about what is happening.

That message may sometimes be reported by format(1m) for a LUN from a disk array, for similar reasons - format(1m) treats a LUN from a disk array just like an individual disk drive. So if a customer runs the format(1m) utility and that disk array LUN responds correctly to an "Inquiry" command, but reports an error for a "Read" command, the same message will be seen from format(1m).

This may occur due to a temporary condition e.g. when the array has just been powered-on or reset. In that case, disk arrays tend to respond quickly to "Inquiry" commands from a host, but they report a sense key of "not ready" for "Read" commands until all of their internal startup processing has been done (which can take a few minutes). If this message from format(1m) is seen from a disk array LUN, even when the disk array has not recently been powered-on or reset, then this requires further investigation on the disk array for possible problems.

Internal Comments
Bug ID 1157327 describes this message and some background information about why it was originally @ introduced. However that bug does not explain the likely causes of seeing that message with modern
disks, hence this HOWTO.

Previously Published As
88136

Change History
Date: 2009-11-25
User Name: Curtis DeCotis
Action: Currency check
Comment: Updated product list

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