I know I have seen various discussions on the list concerning support of various ATLs and tape formats and have read many of them. I now find myself in that awkward position of having to tell management that we are fast approaching the practical usage limit of our ATLs and they are going to have to spend more $ to keep things going.
We are a fairly small TSM shop compared to some. We have two production TSM server sites which are also disaster recovery sites for each other. One site is 3tb of onsite data the second site is 1tb. Since they DR each other each site needs the combined capacity of 4tb plus any growth requirements.
TSM v5.1.8 servers running under Win2000 on Dell servers.
Currently we use two ATLs, one in each site. IBM 3494 with two 3590-e1a scsii drives and one Exabyte ATL with four 8mm Mammoth2 drives. Each site has some external Mammoth2 drives that are used for creating DR tapes.
The 3590 drives/tapes are reliable all the time and fast at everything except start/stop (tape reclamation).
The Mammoth2 drives are mostly reliable but Exabyte support and service SUCK big time. Last drive repalcement they had the drive for 3 months! They claim every error is ALWAYS a tape problem even though there may be five or more tapes giving the same error. Disable rant mode. However the Mammoth2s are good streaming, much better at start/stop than 3590s and are relatively cheap.
Our ATLs each have about 6tb usable and we are going to quickly pass that mark so I am looking to get new ATLs. The mixed tape media environment we have now is somewhat problematic so I want to standardize both sites with the same ATL/drive/media.
Because of cost there is no way a 3494 is going into the smaller site so the question now is which kind of tape format to acquire for both sites.
As I understand it, DLT and LTO both have the slow start/stop processing issues while the AIT and SAIT should have start/stop processing speeds similar to our current Mammoth2 drives.
1) Are any of you using ATLs with AIT drives? What are your experiences with drive and media reliability/durability?
2) For those of you that use DLT or LTO, do you see a real big slowdown in the start/stop processing and what are your experiences with drive and media reliability/durability?
3) For those of you that do see speed issues with start/stop processing on whatever drive you use, how do you handle it? More drives and lower reclaim thresholds or more tapes and higher reclaim thresholds?
As of this moment I am leaning toward ATLs with > 100 slots and AIT3 but am still digesting info on all types. I did notice that the cost for maintenance contracts for AIT ATLs was about 20% lower than for some LTO ATLs. I don't know if this is indicative of higher repair frequency of LTO drives but it must mean something.
Any and all comments on drives/ATLs appreciated.
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Steve Bennett, (907) 465-5783 State of Alaska, Enterprise Technology Services, Technical Services Section
