>Jochem van Hal wrote:
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>
>
>Hi,
>
>Recently, we're trying to decide about the various ways in which TSM can be
>set up. We need about 2Tb of primary pool space. For primary pool only , we
>may either:
>
>1) Get a big library, and a lot of tapes, amounts to >$50.000. (With the
>lib
>we can also maintain the copy pool)
>
>2) Get a bunch of IDE-disk cabinets, and a lot of 70 Gb IDE disks, amounts
>to $25.000 or so (of course we will also need a small library for the copy
>pool). These cabinets have a scsi interface.
>
>It seems IDE disks are not only the cheaper, but also the much faster
>solution for daily retrieve operations. In this case we would opt for a
>RAID-5 IDE set for primary stg (but also a fast(er) SCSI system for the DB
>and LOG). With this amount of disks some are bound to crash every now and
>then, RAID-5 helps. All in all, the TSM server only 'sees' scsi.
>
>One cabinet would show up like one disk, in reality 70Gb disk times 7 disks
>= 0.5 Tb/cabinet, which is a rather big 'disk' size.
>
>Question 1) However, on the forum no-one seems to use a PRimary IDE (PRIDE)
>disk pool? Why? I'm i missing something or what?
>
>Question 2) If PRIDE seems like a good solution, would the better way to
>use
>DISK devices (any TSM limits?, caused by size or sheer number of DISK
>volumes on the PRIDE disk) or FILE devices (but fragmenting files all over
>the disks, and need of reclaim)
>
>Question 3) Any (other) TSM limits endangering this plan (we are talking
>about 2Tb or more on disk...)
>
>Of course OS limits have been accounted for. It seems AIX and NT are OK.
>
>Thank you,
>
>
>Allshare Personnel BV
>Jochem van Hal
>TSM admin
>jvhal AT allshare DOT nl
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>
>-
>
>Here is my personal opinion of how to think about backup data.
>
>1) If only backing up data in the event of a disaster, IE: lots of DB
>files, and that data is hardly ever required to be restored.
>   Keeping this data in a tape library is the best and most cost effective
>solution, full tapes are taken out of the library marked unavailable and
>the storage pool in the library can be X times the size of the amount of
>tapes in.
>   Of course no space reclaim is realistic in this case, and tapes would
>have to be manually place a tape back in the library if needed. (We use
>this method with SAP/Oracle backups and a 7337) consisting of about 40
>DLT(14 in library) tapes holding approx 180G each and all changes based on
>expiration, no
>reclaim. one 180G offsite copy daily runs in the same library.
>   (Although it sounds that this library is a little small for you
>solution, this library runs about 22 hours a day with 180G to the storage
>pool and the offsite copy of said data)
>
>2) If the storage pool which will require some restoration on a limited
>basis. It may still be cost effective to use a tape library. Some
>considerations are, if many of small files changing constantly tape
>transfers are not as good on performance for this, if large amounts of data
>that will require a lot of recliam/move of data.. time may become a issue.
>The initial cost of a library verse a five year cost on disk failure is not
>going to make disk look cheaper and if the library can hold and server the
>data in a manner required it will be the most cost effective solution after
>the five year window.
>
>3) If the storage pool will require a lot of clients with small files and
>is very large and quick online access for restore, then disk is the answer.
>Cost is high and failure is high.
>
>I am sure others have methods of making these decisions, and may be better
>focused for your need.
>
>Good day,
>Bart
>