cciss(4)

🦋 cciss(4) 🦋

okay so bestie, buckle up, because we're reading cciss(4) from the Kernel Interfaces Manual together, and honestly? it's giving vintage. it's giving "my older cousin's server." let's go 💅

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✨ NAME ✨

cciss — the HP Smart Array block driver 🎀

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🌸 SYNOPSIS 🌸

modprobe cciss [ cciss_allow_hpsa=1 ]

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💖 DESCRIPTION 💖

Note: this driver is obsolete and was removed in Linux 4.14, because hpsa(4) ate and left no crumbs in newer kernels. periodt. 😭

cciss is a block driver for the older HP Smart Array RAID controllers, i.e. the elders of the family 👑

🎀 Options 🎀

• cciss_allow_hpsa=1 — this one prevents the cciss driver from even trying to drive any controllers that hpsa(4) is capable of controlling. so lowkey it's a glow-up-restriction: with this option, cciss stays in its lane and only handles these controllers:

Smart Array 5300
Smart Array 5i
Smart Array 532
Smart Array 5312
Smart Array 641
Smart Array 642
Smart Array 6400
Smart Array 6400 EM
Smart Array 6i
Smart Array P600
Smart Array P400i
Smart Array E200i
Smart Array E200
Smart Array E200i
Smart Array E200i
Smart Array E200i
Smart Array E500

(and yes the list literally says Smart Array E200i multiple times, no we're not editing it, the manpage said what it said 🙈)

💫 Supported hardware 💫

the cciss driver supports these Smart Array boards, no cap:

Smart Array 5300
Smart Array 5i
Smart Array 532
Smart Array 5312
Smart Array 641
Smart Array 642
Smart Array 6400
Smart Array 6400 U320 Expansion Module
Smart Array 6i
Smart Array P600
Smart Array P800
Smart Array E400
Smart Array P400i
Smart Array E200
Smart Array E200i
Smart Array E500
Smart Array P700m
Smart Array P212
Smart Array P410
Smart Array P410i
Smart Array P411
Smart Array P812
Smart Array P712m
Smart Array P711m

🔧 Configuration details 🔧

wanna configure your HP Smart Array controllers? you have two paths, bestie:

• use the HP Array Configuration Utility — that's hpacuxe(8) or hpacucli(8)
• or use the Offline ROM-based Configuration Utility (ORCA), which you run from the Smart Array's option ROM at boot time ✨

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📁 FILES 📁

🍓 Device nodes 🍓

the device naming scheme goes a lil something like this:

Major numbers:

104   cciss0
105   cciss1
106   cciss2
105   cciss3
108   cciss4
109   cciss5
110   cciss6
111   cciss7

Minor numbers:

b7 b6 b5 b4 b3 b2 b1 b0
|----+----| |----+----|
     |           |
     |           +-------- Partition ID (0=wholedev, 1-15 partition)
     |
     +-------------------- Logical Volume number

The device naming scheme is:

/dev/cciss/c0d0     Controller 0, disk 0, whole device
/dev/cciss/c0d0p1   Controller 0, disk 0, partition 1
/dev/cciss/c0d0p2   Controller 0, disk 0, partition 2
/dev/cciss/c0d0p3   Controller 0, disk 0, partition 3

/dev/cciss/c1d1     Controller 1, disk 1, whole device
/dev/cciss/c1d1p1   Controller 1, disk 1, partition 1
/dev/cciss/c1d1p2   Controller 1, disk 1, partition 2
/dev/cciss/c1d1p3   Controller 1, disk 1, partition 3

so c is controller, d is disk, p is partition. iykyk 💅

🌈 Files in /proc 🌈

the files /proc/driver/cciss/cciss[0-9]+ are holding all the tea about each controller's configuration. for example:

$ cd /proc/driver/cciss;
$ ls -l;
total 0
-rw-r--r-- 1 root root 0 2010-09-10 10:38 cciss0
-rw-r--r-- 1 root root 0 2010-09-10 10:38 cciss1
-rw-r--r-- 1 root root 0 2010-09-10 10:38 cciss2
$ cat cciss2;
cciss2: HP Smart Array P800 Controller
Board ID: 0x3223103c
Firmware Version: 7.14
IRQ: 16
Logical drives: 1
Current Q depth: 0
Current # commands on controller: 0
Max Q depth since init: 1
Max # commands on controller since init: 2
Max SG entries since init: 32
Sequential access devices: 0

cciss/c2d0:   36.38GB       RAID 0

iconic. obsessed. 🔥

🧚 Files in /sys 🧚

• /sys/bus/pci/devices/dev/ccissX/cXdY/model — shows you the SCSI INQUIRY page 0 model for logical drive Y of controller X
• /sys/bus/pci/devices/dev/ccissX/cXdY/rev — shows you the SCSI INQUIRY page 0 revision for logical drive Y of controller X
• /sys/bus/pci/devices/dev/ccissX/cXdY/unique_id — shows you the SCSI INQUIRY page 83 serial number for logical drive Y of controller X
• /sys/bus/pci/devices/dev/ccissX/cXdY/vendor — shows you the SCSI INQUIRY page 0 vendor for logical drive Y of controller X
• /sys/bus/pci/devices/dev/ccissX/cXdY/block:cciss!cXdY — a symbolic link to /sys/block/cciss!cXdY 🔗
• /sys/bus/pci/devices/dev/ccissX/rescan — when you write to this file, the driver rescans the controller to discover any new, removed, or modified logical drives 👀
• /sys/bus/pci/devices/dev/ccissX/resettable — a value of 1 in here means this controller honors the "reset_devices=1" kernel parameter (the one kdump uses). a value of 0 means the "reset_devices=1" kernel parameter will not be honored. some models of Smart Array just can't honor it, and that's on them 😔
• /sys/bus/pci/devices/dev/ccissX/cXdY/lunid — shows you the 8-byte LUN ID used to address logical drive Y of controller X
• /sys/bus/pci/devices/dev/ccissX/cXdY/raid_level — shows you the RAID level of logical drive Y of controller X
• /sys/bus/pci/devices/dev/ccissX/cXdY/usage_count — shows you the usage count (number of opens) of logical drive Y of controller X

🫶 SCSI tape drive and medium changer support 🫶

SCSI sequential access devices and medium changer devices are supported, and the appropriate device nodes get automatically created for you (e.g. /dev/st0, /dev/st1, etc.; peep st(4) for more deets). but bestie, you must enable "SCSI tape drive support for Smart Array 5xxx" and "SCSI support" in your kernel configuration if you want to use SCSI tape drives with your Smart Array 5xxx controller. no shortcuts 🎀

also, big note: the driver will not engage the SCSI core at init time. you have to direct the driver to dynamically engage the SCSI core via the /proc filesystem entry, which the "block" side of the driver creates as /proc/driver/cciss/cciss* at run time. why? because at driver init time the SCSI core may not be initialized yet (this is a block driver, remember), and trying to register with the SCSI core in that situation would cause a hang 💀 so don't do that.

the move is to do it from an initialization script (typically in /etc/init.d, but it could vary depending on your distribution). for example:

for x in /proc/driver/cciss/cciss[0-9]*
do
    echo "engage scsi" > $x
done

once the SCSI core is engaged by the driver, it cannot be disengaged — the only exception being unloading the driver, if it happens to be linked as a module. so, like, choose wisely ✨

also note: if no sequential access devices or medium changers are detected, the SCSI core will not be engaged by the action of the above script. it simply does nothing, and that's fine.

🌟 Hot plug support for SCSI tape drives 🌟

hot plugging of SCSI tape drives is supported, with some caveats. the cciss driver has to be informed that changes to the SCSI bus have been made, and you can do that via the /proc filesystem. for example:

echo "rescan" > /proc/scsi/cciss0/1

this causes the driver to:

1. query the adapter about changes to the physical SCSI buses and/or fiber channel arbitrated loop, and
2. make note of any new or removed sequential access devices or medium changers.

the driver will output messages telling you which devices have been added or removed, plus the controller, bus, target, and lun used to address each device. then the driver notifies the SCSI midlayer of these changes. teamwork fr fr 🫶

note that the naming convention of the /proc filesystem entries contains a number in addition to the driver name (e.g. "cciss0" instead of just "cciss", which you might've expected). she's specific like that 💅

Note: only sequential access devices and medium changers are presented as SCSI devices to the SCSI midlayer by the cciss driver. specifically, physical SCSI disk drives are not presented to the SCSI midlayer. the only disk devices presented to the kernel are the logical drives that the array controller constructs from regions on the physical drives. those logical drives go to the block layer, not the SCSI midlayer. and it is super important that the driver prevents the kernel from accessing the physical drives directly, because those drives are the ones being used by the array controller to construct the logical drives. do not touch. 🙅‍♀️

💀 SCSI error handling for tape drives and medium changers 💀

the Linux SCSI midlayer has an error-handling protocol that kicks in whenever a SCSI command fails to complete within a certain amount of time (how much time varies depending on the command). the cciss driver participates in this protocol... to some extent. the normal protocol is a four-step process:

1. First, the device is told to abort the command.
2. If that doesn't work, the device is reset.
3. If that doesn't work, the SCSI bus is reset.
4. If that doesn't work, the host bus adapter is reset.

now, cciss is a block driver and a SCSI driver, and only the tape drives and medium changers get presented to the SCSI midlayer. plus, unlike more straightforward SCSI drivers, disk I/O keeps rolling through the block side during the SCSI error-recovery process. so cciss implements only the first two of those actions: aborting the command, and resetting the device. 🌸

also: most tape drives will not oblige in aborting commands, and sometimes it appears they won't even obey a reset command, though in most circumstances they will. if the command cannot be aborted and the device cannot be reset, the device will be set offline. 😭

in the event that the error-handling code is triggered and a tape drive is successfully reset, or the tardy command is successfully aborted, the tape drive may still not allow I/O to continue until some command is issued that positions the tape to a known position. typically you must rewind the tape (by issuing mt -f /dev/st0 rewind for example) before I/O can proceed again to a tape drive that was reset. rewind, bestie, then retry 💖

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👑 SEE ALSO 👑

• hpsa(4)
• cciss_vol_status(8)
• hpacucli(8)
• hpacuxe(8)

http://cciss.sf.net, and Documentation/blockdev/cciss.txt and Documentation/ABI/testing/sysfs-bus-pci-devices-cciss in the Linux kernel source tree 🌈

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and that's the whole page, bestie 🎀 this one's from Linux man-pages 6.20, dated 2026-02-08 — so you're reading the officially-documented, officially-retired legend. periodt. 💅✨🦋