Re: [off-topip] Better Backup Media
On Thu, 23 Jun 2005 at 3:56pm, Mitch Collinsworth wrote On Thu, 23 Jun 2005, Joshua Baker-LePain wrote: Actually, with LTO3, I'm a bit worried about keeping the tape streaming when writing from staged dumps. Native transfer rate of LTO-3 is stated as 288 GB/hr, which is about 76 MiB/s. That's more than most single spindles can handle, *especially* if you're trying to write to tape while other dumps are coming in to the holding disk. Looks like I'll have to do some work on the server end to really get this thing going. Wow, that's impressive. First question is: what does the drive do when you can't feed it data fast enough? Depending on the answer you may or may not actually care enough to worry about it. According to my vendor, LTO is variable speed. So the drive will throttle down to whatever it can get. So, I'll worry about it, but not obsess over it (well, too much at least). -- Joshua Baker-LePain Department of Biomedical Engineering Duke University
Re: [off-topip] Better Backup Media
On Tue, 21 Jun 2005, Chris Loken wrote: BUT - my AIT-4 drive apparently can't even read AIT-3 tapes. Seems mind-bogglingly stupid but my vendor assures me it's true (haven't dared to try). Anybody understand if this is an issue that's going to be resolved and, if so, will it be in firmware or hardware? Answer looks pretty clear from the charts here: http://b2b.sony.com/documents/category/storage/branded-tape/AIT_Drives/AIT-4/AITMedia_05.pdf I suppose it was necessary in order to progress, but bailing on backwards compatibility is very annoying to the customer. It's also not especially good for business. If I've been buying all the AIT line drives, at least in part because the newer ones will read tapes I wrote with the older ones, then I have a business reason to engage in brand loyalty. Once that reason is gone then the next time I upgrade drives, all media choices are back on the table again and I may choose something other than AIT the next time. Didn't the same thing happen with DLT between DLT8000 and SDLT? -Mitch
Re: [off-topip] Better Backup Media
On Thu, 23 Jun 2005 at 10:34am, Mitch Collinsworth wrote Answer looks pretty clear from the charts here: http://b2b.sony.com/documents/category/storage/branded-tape/AIT_Drives/AIT-4/AITMedia_05.pdf Good link -- thanks. Something else I heard on another mailing list: However AIT-4 (unlike AIT-1 til -3) appears to write fill bytes onto the tape if it's not fed with data quickly enough, thus wasting lots of capacity. The person said they heard it somewhere and hadn't seen it confirmed. If true, though... yuck. -- Joshua Baker-LePain Department of Biomedical Engineering Duke University
Re: [off-topip] Better Backup Media
Thanks for the link, was not aware about that, just assumed it should be backwards compatiable. Really likes AIT. Yeah, it definitly going to make us think twice before upgrading. Chen On Tue, 21 Jun 2005, Chris Loken wrote: BUT - my AIT-4 drive apparently can't even read AIT-3 tapes. Seems mind-bogglingly stupid but my vendor assures me it's true (haven't dared to try). Anybody understand if this is an issue that's going to be resolved and, if so, will it be in firmware or hardware? Answer looks pretty clear from the charts here: http://b2b.sony.com/documents/category/storage/branded-tape/AIT_Drives/AIT-4/AITMedia_05.pdf I suppose it was necessary in order to progress, but bailing on backwards compatibility is very annoying to the customer. It's also not especially good for business. If I've been buying all the AIT line drives, at least in part because the newer ones will read tapes I wrote with the older ones, then I have a business reason to engage in brand loyalty. Once that reason is gone then the next time I upgrade drives, all media choices are back on the table again and I may choose something other than AIT the next time. Didn't the same thing happen with DLT between DLT8000 and SDLT? -Mitch === Yu Chen Howard Hughes Medical Institute Chemistry Building, Rm 182 University of Maryland at Baltimore County 1000 Hilltop Circle Baltimore, MD 21250 phone: (410)455-6347 (primary) (410)455-2718 (secondary) fax:(410)455-1174 email: [EMAIL PROTECTED] ===
Re: [off-topip] Better Backup Media
On Thu, 23 Jun 2005, Joshua Baker-LePain wrote: Something else I heard on another mailing list: However AIT-4 (unlike AIT-1 til -3) appears to write fill bytes onto the tape if it's not fed with data quickly enough, thus wasting lots of capacity. The person said they heard it somewhere and hadn't seen it confirmed. If true, though... yuck. Well, maybe, maybe not. DLT8000 did that, too. Lots of people griped bitterly about poor performance with their DLT4000's and 7000's. Problem was usually that their 1-pass backup software kept starving the write buffer and the drives had to shoe-shine in order to deal with it. The DLT8000 had variable speed write, which meant the tape kept streaming and the data was laid down as fast as it came in, even if that was slower than what the tape could handle. I always had a good chuckle at conferences listening to vendors trying to explain this problem to all the folks griping about their expensive tape drives that would only write at a fraction of their advertised speed. In general the vendors would do everything they could to avoid pointing the blame at the expensive commercial backup software products because they usually sold that to the customers, too. The good news for amanda users is that when you stage your dumps to holding disk, you eliminate the most frequent cause of the data starvation problem, which is the backup program scouring the partition looking for which files to backup today. Once you have your data on the holding disk you're unlikely to starve the tape drive and it can stream the data at full speed onto the tape. If it can't, you have a h/w problem that is typically easy to fix. -Mitch
Re: [off-topip] Better Backup Media
On Thu, 23 Jun 2005 at 11:46am, Mitch Collinsworth wrote On Thu, 23 Jun 2005, Joshua Baker-LePain wrote: Something else I heard on another mailing list: However AIT-4 (unlike AIT-1 til -3) appears to write fill bytes onto the tape if it's not fed with data quickly enough, thus wasting lots of capacity. The person said they heard it somewhere and hadn't seen it confirmed. If true, though... yuck. Well, maybe, maybe not. DLT8000 did that, too. Lots of people griped bitterly about poor performance with their DLT4000's and 7000's. Problem was usually that their 1-pass backup software kept starving the write buffer and the drives had to shoe-shine in order to deal with it. The DLT8000 had variable speed write, which meant the tape kept streaming and the data was laid down as fast as it came in, even if that was slower than what the tape could handle. Indeed -- the other person referred to the AIT-4 behavior as DLT syndrome. But isn't variable speed write different than writing fill bytes? Does DLT8000 lose capacity when not writing as fast as it can? The good news for amanda users is that when you stage your dumps to holding disk, you eliminate the most frequent cause of the data starvation problem, which is the backup program scouring the partition looking for which files to backup today. Once you have your data on the holding disk you're unlikely to starve the tape drive and it can stream the data at full speed onto the tape. If it can't, you have a h/w problem that is typically easy to fix. Actually, with LTO3, I'm a bit worried about keeping the tape streaming when writing from staged dumps. Native transfer rate of LTO-3 is stated as 288 GB/hr, which is about 76 MiB/s. That's more than most single spindles can handle, *especially* if you're trying to write to tape while other dumps are coming in to the holding disk. Looks like I'll have to do some work on the server end to really get this thing going. -- Joshua Baker-LePain Department of Biomedical Engineering Duke University
Re: [off-topip] Better Backup Media
On Thu, 23 Jun 2005, Joshua Baker-LePain wrote: Indeed -- the other person referred to the AIT-4 behavior as DLT syndrome. But isn't variable speed write different than writing fill bytes? Does DLT8000 lose capacity when not writing as fast as it can? Yes. Same idea. Tape spins at constant rate, data is written as fast as possible or else as fast as it comes in. They probably had some minimum below which it would stop and restart, but you'd get more on a tape if you could keep the write buffer from starving. Actually, with LTO3, I'm a bit worried about keeping the tape streaming when writing from staged dumps. Native transfer rate of LTO-3 is stated as 288 GB/hr, which is about 76 MiB/s. That's more than most single spindles can handle, *especially* if you're trying to write to tape while other dumps are coming in to the holding disk. Looks like I'll have to do some work on the server end to really get this thing going. Wow, that's impressive. First question is: what does the drive do when you can't feed it data fast enough? Depending on the answer you may or may not actually care enough to worry about it. -Mitch
Re: [off-topip] Better Backup Media
Fabricio Luiz Machado wrote: Some of my DDS-4 tapes are bad (I/O error). So... i´m thinking if these tapes are trustworthy... :-/ Are there another better solution, that I can trust more than DDS-4 ? Maybe DLT ? Many people say DLT is better than DDS, but I personally have had some very bad experiences with DLT *drives*, so I've ditched that technology and never want to touch it again. Using LTO has been nothing but joy these past 2 years. I still have one DDS4 drive in service and it's been quite reliable - you just need to use the cleaning tape regularly. But some DDS drives *have* died on me. -- Toomas Aas
Re: [off-topip] Better Backup Media
Agree here. We like AIT. And now AIT-4 is out. Chen On Mon, Jun 20, 2005 at 08:17:55PM -0300, Fabricio Luiz Machado wrote: Hi. Some of my DDS-4 tapes are bad (I/O error). So... i?m thinking if these tapes are trustworthy... :-/ Are there another better solution, that I can trust more than DDS-4 ? Maybe DLT ? DLT has a good track record, but is expensive and been obsoleted by newer technologies. A lot of us here speak very highly of AIT, and it's positioned to replace DDS in the market. I'd look into AIT. Brandon === Yu Chen Howard Hughes Medical Institute Chemistry Building, Rm 182 University of Maryland at Baltimore County 1000 Hilltop Circle Baltimore, MD 21250 phone: (410)455-6347 (primary) (410)455-2718 (secondary) fax:(410)455-1174 email: [EMAIL PROTECTED] ===
Re: [off-topip] Better Backup Media
On Tue, 21 Jun 2005 at 11:41am, Toomas Aas wrote Fabricio Luiz Machado wrote: Some of my DDS-4 tapes are bad (I/O error). So... i´m thinking if these tapes are trustworthy... :-/ Are there another better solution, that I can trust more than DDS-4 ? Maybe DLT ? I can second the comments recommending AIT. I have both AIT-1 and AIT-3 drives and both have been highly reliable. I'm looking at upgrading capacity (see below), and my vendor also spoke very highly of AIT. Many people say DLT is better than DDS, but I personally have had some very bad experiences with DLT *drives*, so I've ditched that technology and never want to touch it again. Using LTO has been nothing but joy these past 2 years. As long as we're talking drives and media (and I'm in the market), does anyone have any experience with S-AIT? According to my vendor, it has the same smart compresser as AIT and a capacity of 500GB/tape (vs. 400GB for LTO-3). LTO-3 looks like it may be the winner on price, but if there's a good reason to go S-AIT, I'm not averse to doing so. -- Joshua Baker-LePain Department of Biomedical Engineering Duke University
Re: [off-topip] Better Backup Media
On Tue, Jun 21, 2005 at 09:20:45AM -0400, Joshua Baker-LePain wrote: As long as we're talking drives and media (and I'm in the market), does anyone have any experience with S-AIT? According to my vendor, it has the same smart compresser as AIT and a capacity of 500GB/tape (vs. 400GB for LTO-3). LTO-3 looks like it may be the winner on price, but if there's a good reason to go S-AIT, I'm not averse to doing so. I don't have any SAIT experience, but the last time I looked, the big limitation for me was that nobody but Sony was selling a library with SAIT drives in it, and Sony was only selling them in their high end tape silos. That may have changed since the last time I looked. I seem to remember maybe seeing a Spectra Logic box with a SAIT drive in it at a conference sometime recently. I know that Overland isn't offering them in their Neo libraries, which is where I'd really like to see one. If I replace my Overland it'll probably be with another. It's been highly reliable. Right now SAIT looks to me like it'll probably win out over LTO for density and speed in the near term and in the long term, but helical scan has always been harder to sell than linear tape. The AIT technology has been highly reliable for me and seems to be as reliable for everyone else as well. AIT may finally be the technology that gets helical scan into the real enterprise market, but until you see an AIT derivative in an STK silo for instance, it seems like SAIT is going to remain a specialty product. Who knows, maybe this has all changed in the past few months, or is in the process of changing now. AIT-4 sure looks pretty though. Brandon -- Pseudo-Random Googlism: birthday is here; commemoration to continue
Re: [off-topip] Better Backup Media
On Tue, 21 Jun 2005 at 9:36am, Brandon D. Valentine wrote On Tue, Jun 21, 2005 at 09:20:45AM -0400, Joshua Baker-LePain wrote: As long as we're talking drives and media (and I'm in the market), does anyone have any experience with S-AIT? According to my vendor, it has the same smart compresser as AIT and a capacity of 500GB/tape (vs. 400GB for LTO-3). LTO-3 looks like it may be the winner on price, but if there's a good reason to go S-AIT, I'm not averse to doing so. I don't have any SAIT experience, but the last time I looked, the big limitation for me was that nobody but Sony was selling a library with SAIT drives in it, and Sony was only selling them in their high end tape silos. That may have changed since the last time I looked. I seem to On their website now I see the CSM-20 -- 1-2 drives, 20 tapes, 5U. Qualstar also sells a higher end one -- 1-4 drives, 33 tapes, and expandable. remember maybe seeing a Spectra Logic box with a SAIT drive in it at a conference sometime recently. I know that Overland isn't offering them in their Neo libraries, which is where I'd really like to see one. If I replace my Overland it'll probably be with another. It's been highly reliable. Yup, I like Overland a lot as well. My AIT-3 changer is a LoaderExpress, and the LTO-3 quote I got is for a Neo-2000. As you noted, they're (still) not doing SAIT. AIT-4 sure looks pretty though. But still only 200GB/tape, which for me isn't a compelling upgrade over AIT-3. -- Joshua Baker-LePain Department of Biomedical Engineering Duke University
Re: [off-topip] Better Backup Media
Brandon D. Valentine wrote: AIT-4 sure looks pretty though. We've used AIT-3 for a couple of years and AIT-4 for 6-months or so. No significant problems. BUT - my AIT-4 drive apparently can't even read AIT-3 tapes. Seems mind-bogglingly stupid but my vendor assures me it's true (haven't dared to try). Anybody understand if this is an issue that's going to be resolved and, if so, will it be in firmware or hardware? Chris
[off-topip] Better Backup Media
Hi. Some of my DDS-4 tapes are bad (I/O error). So... i´m thinking if these tapes are trustworthy... :-/ Are there another better solution, that I can trust more than DDS-4 ? Maybe DLT ? thanks! Fabricio. ___ Yahoo! Acesso Grátis - Internet rápida e grátis. Instale o discador agora! http://br.acesso.yahoo.com/
Re: [off-topip] Better Backup Media
On Mon, Jun 20, 2005 at 08:17:55PM -0300, Fabricio Luiz Machado wrote: Hi. Some of my DDS-4 tapes are bad (I/O error). So... i?m thinking if these tapes are trustworthy... :-/ Are there another better solution, that I can trust more than DDS-4 ? Maybe DLT ? DLT has a good track record, but is expensive and been obsoleted by newer technologies. A lot of us here speak very highly of AIT, and it's positioned to replace DDS in the market. I'd look into AIT. Brandon -- Pseudo-Random Googlism: sunshine is on a rage in japan
