SSA under Linux - Aix

This is a discussion on SSA under Linux - Aix ; I installed RHEL3U8 on an IBM 660 today and realized that it can't see my SSA adapter and attached disks (SSA storage model no. 7133- D40), however googling did _not_ give a good answer. Does anybody know if SSA is ...

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Thread: SSA under Linux

  1. SSA under Linux

    I installed RHEL3U8 on an IBM 660 today and realized that it can't
    see my SSA adapter and attached disks (SSA storage model no. 7133-
    D40),
    however googling did _not_ give a good answer.
    Does anybody know if SSA is supported by RHEL (Cards, drivers)?


    Thanks


  2. Re: SSA under Linux

    hmmmm .. did you google groups ?

    http://groups.google.co.uk/groups?q=...=1&sa=N&tab=wg

    The answer looks like "no" linux does not support SSA.

    Rgds
    Mark Taylor


  3. Re: SSA under Linux

    However ref: http://www.vergenet.net/linux/redund...y-HOWTO-7.html

    Linux SSA Device Driver

    There is no Linux SSA device driver today, however IBM Systems Storage
    Division (SSD) will support us to get one written for the IBM PCI SSA
    adapter -- and possibly officially endorse it, at least that is the
    usual process. There are at least two well-known SCSI device driver
    authors in the Linux community who are more than keen to write the
    device driver. I will get loan hardware and the device driver
    development toolkit in time. The loan contract will only be valid for
    90 days, though, after which we will probably need to return the loan
    hardware. Donations are more than welcome!

    I also contacted Pathlight Technology Inc.. Pathlight offers a single
    loop PCI SSA adapter which is simpler and probably cheaper than the
    IBM adapter. Pathlight is also going to support us but they currently
    have a problem with releasing the driver source code because it
    contains some parts which are considered confidential.

    SSA documentation is available for free on the SSA Industry
    Association's Documentation and Standards page or from the Symbios
    Logic, Inc. anonymous FTP server.

    A couple of prerequisites have to be fulfilled prior to getting the
    SSA device driver reasonably done. A major difference of SSA compared
    to external RAID boxes is that all disks are seen by the operating
    system individually. This currently limits us to 16 SCSI/SSA disks due
    to the major/minor device number scheme in the Linux kernel. (It
    appears the current development trend is to go for a 64 bit dev_t
    value which would allow us to use at least 16 bits for the minor
    device number.)

    Remark: There is also a PCI SSA RAID adapter from IBM which does RAID
    levels 0 (striping), 1 (mirroring) and 5 (striping with parity) in
    hardware. The current adapter firmware doesn't support more than one
    adapter in a loop, however, which makes it unusable for multi-host
    attachments. This could change before too long. RAID 5 organized
    bunches of disks are presented to the operating system as single
    entities, and the adapter can group up to 14 plus 1 disks in a RAID 5
    configuration. Since the biggest SSA disk is currently 9.1 GB, this
    sums up to 14 times 9.1 GB = 127.4 GB as a single entity. Please keep
    in mind that due to parity sum calculations which are needed for every
    write operation, mirrored setups (RAID level 1) are usually faster on
    writes than RAID level 5.

    According to the SCSI development folks, the current Linux SCSI mid
    layer code is too slow to handle SSA data rates efficiently. This is a
    known problem which will hopefully be fixed as soon as there is a SSA
    device driver available.

    Design Request: I herewith ask the Linux SCSI developers/maintainers
    to fix this as soon as possible, as well as re-design the disk and
    device numbering scheme to support more than 16 SCSI disks.

    The SSA driver will also need to support SSA Target Mode (see section
    Non-IP Heartbeat).

    The Vicom SLIC

    Another way to attach SSA disks to a Linux machine is to use the so-
    called Serial Loop Interface Card (SLIC) built by Vicom Systems, Inc..
    This device is also offered by IBM with the feature code #7190. The
    SLIC basically converts a F/W/D SCSI bus to a single SSA loop which
    can have up to 32 disks. The SLIC presents the disks to the operating
    system as 32 SCSI LUNs (logical units) on a single SCSI ID (remember
    we still have the 16 SCSI disks limitation inside Linux). The good
    news is that as long as the SLIC is the only SCSI target on the SCSI
    bus, there is no bus arbitration overhead. This results in a maximum
    sustained throughput of 18 MByte/s. The current SLIC supports only one
    SSA initiator per loop which is not good for a twin-tailed
    configuration but the requirement for multiple-initiator is recognized
    and will eventually be fulfilled. There will also be Ultra-SCSI
    versions which will sort of double the throughput.

    Pathlight Technology Inc.

    Pathlight who was mentioned before is also going to release several
    SCSI-to-SSA converter tools. At NAB 97, they announced some
    interesting new products: a SSA 16 port hub is ready and in
    production, SSA Network Agent which interconnects SSA and Ultra Wide
    SCSI and Ethernet in one box and enables SCSI and SSA initiators and
    targets to transfer data between each other. Also they announced a new
    small black box called "Magic" that extends the SSA cable length to
    100 meters (300 feet) on twisted pair copper cable.

    HTH
    Mark taylor



  4. Re: SSA under Linux

    Mark Taylor wrote:
    > However ref: http://www.vergenet.net/linux/redund...y-HOWTO-7.html
    >
    > Linux SSA Device Driver
    >
    > There is no Linux SSA device driver today, however IBM Systems Storage
    > Division (SSD) will support us to get one written for the IBM PCI SSA
    > adapter -- and possibly officially endorse it, at least that is the
    > usual process. There are at least two well-known SCSI device driver
    > authors in the Linux community who are more than keen to write the
    > device driver. I will get loan hardware and the device driver
    > development toolkit in time. The loan contract will only be valid for
    > 90 days, though, after which we will probably need to return the loan
    > hardware. Donations are more than welcome!
    >
    > I also contacted Pathlight Technology Inc.. Pathlight offers a single
    > loop PCI SSA adapter which is simpler and probably cheaper than the
    > IBM adapter. Pathlight is also going to support us but they currently
    > have a problem with releasing the driver source code because it
    > contains some parts which are considered confidential.
    >
    > SSA documentation is available for free on the SSA Industry
    > Association's Documentation and Standards page or from the Symbios
    > Logic, Inc. anonymous FTP server.
    >
    > A couple of prerequisites have to be fulfilled prior to getting the
    > SSA device driver reasonably done. A major difference of SSA compared
    > to external RAID boxes is that all disks are seen by the operating
    > system individually. This currently limits us to 16 SCSI/SSA disks due
    > to the major/minor device number scheme in the Linux kernel. (It
    > appears the current development trend is to go for a 64 bit dev_t
    > value which would allow us to use at least 16 bits for the minor
    > device number.)
    >
    > Remark: There is also a PCI SSA RAID adapter from IBM which does RAID
    > levels 0 (striping), 1 (mirroring) and 5 (striping with parity) in
    > hardware. The current adapter firmware doesn't support more than one
    > adapter in a loop, however, which makes it unusable for multi-host
    > attachments. This could change before too long. RAID 5 organized
    > bunches of disks are presented to the operating system as single
    > entities, and the adapter can group up to 14 plus 1 disks in a RAID 5
    > configuration. Since the biggest SSA disk is currently 9.1 GB, this
    > sums up to 14 times 9.1 GB = 127.4 GB as a single entity. Please keep
    > in mind that due to parity sum calculations which are needed for every
    > write operation, mirrored setups (RAID level 1) are usually faster on
    > writes than RAID level 5.
    >
    > According to the SCSI development folks, the current Linux SCSI mid
    > layer code is too slow to handle SSA data rates efficiently. This is a
    > known problem which will hopefully be fixed as soon as there is a SSA
    > device driver available.
    >
    > Design Request: I herewith ask the Linux SCSI developers/maintainers
    > to fix this as soon as possible, as well as re-design the disk and
    > device numbering scheme to support more than 16 SCSI disks.
    >
    > The SSA driver will also need to support SSA Target Mode (see section
    > Non-IP Heartbeat).
    >
    > The Vicom SLIC
    >
    > Another way to attach SSA disks to a Linux machine is to use the so-
    > called Serial Loop Interface Card (SLIC) built by Vicom Systems, Inc..
    > This device is also offered by IBM with the feature code #7190. The
    > SLIC basically converts a F/W/D SCSI bus to a single SSA loop which
    > can have up to 32 disks. The SLIC presents the disks to the operating
    > system as 32 SCSI LUNs (logical units) on a single SCSI ID (remember
    > we still have the 16 SCSI disks limitation inside Linux). The good
    > news is that as long as the SLIC is the only SCSI target on the SCSI
    > bus, there is no bus arbitration overhead. This results in a maximum
    > sustained throughput of 18 MByte/s. The current SLIC supports only one
    > SSA initiator per loop which is not good for a twin-tailed
    > configuration but the requirement for multiple-initiator is recognized
    > and will eventually be fulfilled. There will also be Ultra-SCSI
    > versions which will sort of double the throughput.
    >
    > Pathlight Technology Inc.
    >
    > Pathlight who was mentioned before is also going to release several
    > SCSI-to-SSA converter tools. At NAB 97, they announced some
    > interesting new products: a SSA 16 port hub is ready and in
    > production, SSA Network Agent which interconnects SSA and Ultra Wide
    > SCSI and Ethernet in one box and enables SCSI and SSA initiators and
    > targets to transfer data between each other. Also they announced a new
    > small black box called "Magic" that extends the SSA cable length to
    > 100 meters (300 feet) on twisted pair copper cable.
    >
    > HTH
    > Mark taylor
    >
    >

    Yaaaaay!

    I have an F50 running FC6 that could use the installed disk space. It
    is a very adequate machine to run this OS, but I am doing some syslog
    collection with it and this driver would be da bomb.

    Please keep this group posted with any details.

    SG

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