Re: [OT] best tape backup system?
And worse yet, you have to run them to the end and then rewind them if you are going to keep the data for long [the magnetic fields affect layers near them]. An array of RAID1 disks, which sleep deeply [off] between uses would probably be affordable, and last MUCH longer. Just my 2 cents worth- ya, well, that's what you get for 2 cents. b- Mark Hahn wrote: Not sure if it is important to many people, but tapes take a lot less electricity than online disks. do you really care? an active disk is about 15W, inactive 5W and asleep nearly zero. even assuming idle-but-spinning, I make that as about $2/year. tapes are wonderful in every way except one: they're finicky and difficult to care for properly. for instance, do you have a humidity and temperature-controlled place to store them? and have you actually logged the temp/hum for that to see whether, for instance, it gets warm on weekends? if I were forced to use tapes, I would insist on making 2+ copies of everything. note that this clearly hurt's tape's competitiveness WRT price, size, bandwidth, etc. I don't see any new tape installations that are not driven by secondary factors such as big piles of old data already on tape, or someone wanting to physically move the media into a vault. (on that topic, I don't buy the idea that tape's less vulnerable to hacking, either. just because your backup is on disk doesn't mean that it's online or accessible. similarly, just because your tape is in a separate cabinet doesn't mean that a sufficiently motivated badguy could not get the tape put into some drive...) regards, mark hahn. (buying many TB of disk this year and no tape) - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html . - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [OT] best tape backup system?
> Not sure if it is important to many people, but tapes take a lot less > electricity than online disks. do you really care? an active disk is about 15W, inactive 5W and asleep nearly zero. even assuming idle-but-spinning, I make that as about $2/year. tapes are wonderful in every way except one: they're finicky and difficult to care for properly. for instance, do you have a humidity and temperature-controlled place to store them? and have you actually logged the temp/hum for that to see whether, for instance, it gets warm on weekends? if I were forced to use tapes, I would insist on making 2+ copies of everything. note that this clearly hurt's tape's competitiveness WRT price, size, bandwidth, etc. I don't see any new tape installations that are not driven by secondary factors such as big piles of old data already on tape, or someone wanting to physically move the media into a vault. (on that topic, I don't buy the idea that tape's less vulnerable to hacking, either. just because your backup is on disk doesn't mean that it's online or accessible. similarly, just because your tape is in a separate cabinet doesn't mean that a sufficiently motivated badguy could not get the tape put into some drive...) regards, mark hahn. (buying many TB of disk this year and no tape) - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [OT] best tape backup system?
We must be in 2 different worlds!!! I can have wide LVD and narrow SE on the same card (2940U2W). And wide ultra and narrow SE on the same card (2940UW). That is why the card is so good. IMO. Just not with linux. The OS that must not be named, supports the above. :( In fact, I have a PC with a 2940UW with 2 disks (UW), 2 CDs, 1 DDS3 and a zip drive. All happy with OS to not be named 98. Maybe I should try knopix, and see if that system likes Linux. However, as I said before. I did not swap out every component. I used the same disks every time, but did swap the data cables, tape drives, SCSI cards and terminators. But those disks still work today in U2W (LVD-80) mode. My last attempt to mix SCSI disks and tapes was over 1 year ago, using RH9. On previous attempts I would have used RH7. I don't recall ever using RH8. Guy -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Michael Tokarev Sent: Wednesday, February 23, 2005 1:29 PM To: linux-raid@vger.kernel.org Subject: Re: [OT] best tape backup system? Guy wrote: > I know a thing or 2 about SCSI. I know I had it correct. 1 config was all > wide LVD (2940U2W). My card has a LVD and a SE port on the same logical > SCSI bus. I was surprized once when I noticied such "logical SCSI bus" really isn't "logical" per se. I mean, if I plug ANY device into the "SE port", all devices, including the ones attached to "LVD port" switches to SE mode. Another channel - yes, sure, but not another port (connector) on the same channel. Well, I can't say for all vendors and all cards, but the ones we have here (mostly adaptec and ncr/sym) works this way. For example, Adaptec AHA-3940U2x controller: it's 2-channel card with 3 ports, two 68pin LVD/SE (one per channel) and one older "scsi-like-ide" connector attached to 1st channel -- any device attached to this last connector forces the whole 1st channel to go into SE mode, and no LVD-only device works (in fact, it does not work at all in this case with any LVD-only device attached). > Another config was wide LVD disks and a narrow SE tape. Another, > my disks support SE, I had all SE wide and narrow. Correct terminators in > each case. I also tried a 2940UW, no LVD, all SE. All configs worked if I > only used the disks or the tape drives, but failed if I used disks and tape > at the same time. Well, this is weird. We have numerous configurations with mixed tapes and disks (and other stuff) and had no single problem so far, everything just works (except of that obvious LVD vs SE issue). Including 2940UW and other controllers. /mjt - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [OT] best tape backup system?
Guy wrote: I know a thing or 2 about SCSI. I know I had it correct. 1 config was all wide LVD (2940U2W). My card has a LVD and a SE port on the same logical SCSI bus. I was surprized once when I noticied such "logical SCSI bus" really isn't "logical" per se. I mean, if I plug ANY device into the "SE port", all devices, including the ones attached to "LVD port" switches to SE mode. Another channel - yes, sure, but not another port (connector) on the same channel. Well, I can't say for all vendors and all cards, but the ones we have here (mostly adaptec and ncr/sym) works this way. For example, Adaptec AHA-3940U2x controller: it's 2-channel card with 3 ports, two 68pin LVD/SE (one per channel) and one older "scsi-like-ide" connector attached to 1st channel -- any device attached to this last connector forces the whole 1st channel to go into SE mode, and no LVD-only device works (in fact, it does not work at all in this case with any LVD-only device attached). Another config was wide LVD disks and a narrow SE tape. Another, my disks support SE, I had all SE wide and narrow. Correct terminators in each case. I also tried a 2940UW, no LVD, all SE. All configs worked if I only used the disks or the tape drives, but failed if I used disks and tape at the same time. Well, this is weird. We have numerous configurations with mixed tapes and disks (and other stuff) and had no single problem so far, everything just works (except of that obvious LVD vs SE issue). Including 2940UW and other controllers. /mjt - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [OT] best tape backup system?
I know a thing or 2 about SCSI. I know I had it correct. 1 config was all wide LVD (2940U2W). My card has a LVD and a SE port on the same logical SCSI bus. Another config was wide LVD disks and a narrow SE tape. Another, my disks support SE, I had all SE wide and narrow. Correct terminators in each case. I also tried a 2940UW, no LVD, all SE. All configs worked if I only used the disks or the tape drives, but failed if I used disks and tape at the same time. I am convinced I had many valid configurations, none worked until I used 2 SCSI cards. My system has grown, it now has 5 SCSI buses, 17 disk drives and 2 tape drives. Works just fine. But no tape on the same SCSI bus as disks. Guy -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Michael Tokarev Sent: Tuesday, February 22, 2005 4:53 PM To: linux-raid@vger.kernel.org Subject: Re: [OT] best tape backup system? Guy wrote: > I have NOT been able to share a SCSI cable/card with disks and a tape drive. > Tried for days. I would get disk errors, or timeouts. I corrected the > problem by putting the tape drive on a dedicated SCSI bus/card. I don't > recall the details of the failures, since it has been well over a year now. > But I do know I only had problems while using the tape drive and the disks > at the same time. Like, during a backup. The disks were happy while the > tape drive was idle. I also swapped parts, it had no effect. I assumed > Linux does not like to share SCSI. There may be various reasons for this, and i think all of them are related to hardware only, esp. to the SCSI bus. Eg, some modern disk drives don't understand SE mode anymore, so can't be plugged into an scsi bus with at least one SE device. On the other hand, it was qutie common for esp. old tapes to NOT understand LVD mode. Obviously you can't mix that sort of devices on the same bus. I guess the bus where you drives are is in LVD mode while tapes works in SE mode... BTW, I've seen quite modern tape drive with an old scsi connector (I don't even remember anymore how it's called -- the one which looks pretty like an IDE connector but a bit wider and with more (80?) pins; with max speed of 20Mb/sec aka 10MHz or so) inside the case and with an adaptor for current 68pin scsi connector standard. Obviously it works in SE mode only (that bus worked in that mode only). Don't remember which vendor that drive was... /mjt - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [OT] best tape backup system?
hi ya On Tue, 22 Feb 2005, Jon Lewis wrote: > I should clarify, that's 80GB per tape...so 800GB native assumes you have > 10 tapes in the unit. yup...seen those puppies too ... too much headache for me > > i keep wondering why people pay $150K for 1TB brandname tape subsystems .. > > I wouldn't pay that much... the odd part is people do :-) just because its "name branded enterprise blah blah" > but I think the "common wisdom" is that tape is > more durable/portable than disks. Once upon a time, it was cheaper than > disks too...but that's no longer the case. yup ... and disks have become more reliable tapes still ahve the same problem they always had ... the heads need to be cleaned, and if the drive unit goes in for repair, you have no alternative options - i usually get those calls, from panicky folks, which there is no solution other than buy 2 tape drives or buy disk-based backups in addition to tapes if they like tapes both tape and disk backups have its purposes and reasons > It's part of why my plan to > buy a bunch of Exabyte stuff got shot down and instead we bought P4's with > 1TB SATA-RAID5 arrays to use as "backup servers". i'd buy 2 disk based backups, because one has to backup the backup server :-) - disks is cheap, compared to loss of 1TB of corp data or 10TB of corp data is more along the lines of fun when things become interesting :-) -- david> Not sure if it is important to many people, but tapes take a lot david> less electricity than online disks. i doubt that it'd be a factor in buying tapes vs disks, but one never knows :-0 they should be more worried about magnets and phones next to the tape or tapes under the old fashion crt's - you'd be surprise what one finds, when one goes into "server rooms" which i guess is the fun part, fixing their problems c ya alvin - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [OT] best tape backup system?
Not sure if it is important to many people, but tapes take a lot less electricity than online disks. --David Dougall On Tue, 22 Feb 2005, Jon Lewis wrote: > On Tue, 22 Feb 2005, Alvin Oga wrote: > > > > Better depends on what you want/need/can afford. Last time I was tape > > > shopping, I thought this would be a good compromise on the need/can > > > afford: > > > Exabyte VXA-2 Packetloader 1x10 > > > > > > Native tape capacity is 800gb. The only downside is, no magazine...it > > > stores the tapes in an internal carosel accessed from the front, one > > > position at a time. For a bit more $, they have magazine based tape > > > library systems with VXA-2 drives. > > > > for 1TB of storage ... i'd put the data on 4 disks ( raided ) > > and take the disks and put in nice bubble wrap and nice cushion > > I should clarify, that's 80GB per tape...so 800GB native assumes you have > 10 tapes in the unit. > > > i keep wondering why people pay $150K for 1TB brandname tape subsystems .. > > I wouldn't pay that much...but I think the "common wisdom" is that tape is > more durable/portable than disks. Once upon a time, it was cheaper than > disks too...but that's no longer the case. It's part of why my plan to > buy a bunch of Exabyte stuff got shot down and instead we bought P4's with > 1TB SATA-RAID5 arrays to use as "backup servers". > > -- > Jon Lewis | I route > Senior Network Engineer | therefore you are > Atlantic Net| > _ http://www.lewis.org/~jlewis/pgp for PGP public key_ > - > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to [EMAIL PROTECTED] > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [OT] best tape backup system?
On Tue, 22 Feb 2005, Alvin Oga wrote: > > Better depends on what you want/need/can afford. Last time I was tape > > shopping, I thought this would be a good compromise on the need/can > > afford: > > Exabyte VXA-2 Packetloader 1x10 > > > > Native tape capacity is 800gb. The only downside is, no magazine...it > > stores the tapes in an internal carosel accessed from the front, one > > position at a time. For a bit more $, they have magazine based tape > > library systems with VXA-2 drives. > > for 1TB of storage ... i'd put the data on 4 disks ( raided ) > and take the disks and put in nice bubble wrap and nice cushion I should clarify, that's 80GB per tape...so 800GB native assumes you have 10 tapes in the unit. > i keep wondering why people pay $150K for 1TB brandname tape subsystems .. I wouldn't pay that much...but I think the "common wisdom" is that tape is more durable/portable than disks. Once upon a time, it was cheaper than disks too...but that's no longer the case. It's part of why my plan to buy a bunch of Exabyte stuff got shot down and instead we bought P4's with 1TB SATA-RAID5 arrays to use as "backup servers". -- Jon Lewis | I route Senior Network Engineer | therefore you are Atlantic Net| _ http://www.lewis.org/~jlewis/pgp for PGP public key_ - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [OT] best tape backup system?
On Tue, 22 Feb 2005, Jon Lewis wrote: > On Tue, 22 Feb 2005, Louis-David Mitterrand wrote: > > > I am considering getting a Sony SAIT 3 with 500G/1TB tapes, which seems > > like a nice solution for backuping a whole server on a single tape. > > > > Has anyone used that hardware and can comment on its performance, > > linux-compatibility or otherwise? > > > > Is there a better solution out there? > > Better depends on what you want/need/can afford. Last time I was tape > shopping, I thought this would be a good compromise on the need/can > afford: > Exabyte VXA-2 Packetloader 1x10 > > Native tape capacity is 800gb. The only downside is, no magazine...it > stores the tapes in an internal carosel accessed from the front, one > position at a time. For a bit more $, they have magazine based tape > library systems with VXA-2 drives. for 1TB of storage ... i'd put the data on 4 disks ( raided ) and take the disks and put in nice bubble wrap and nice cushion :-) don't pop the bubbles and yup.. i want the fast restore of 1TB of data too which to me is more important than the $50 or $100 tape costs (plus the tape drive) vs $600 set of 1TB disk c ya alvin i keep wondering why people pay $150K for 1TB brandname tape subsystems .. :-) - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [OT] best tape backup system?
On Tue, 22 Feb 2005, Louis-David Mitterrand wrote: > I am considering getting a Sony SAIT 3 with 500G/1TB tapes, which seems > like a nice solution for backuping a whole server on a single tape. > > Has anyone used that hardware and can comment on its performance, > linux-compatibility or otherwise? > > Is there a better solution out there? Better depends on what you want/need/can afford. Last time I was tape shopping, I thought this would be a good compromise on the need/can afford: Exabyte VXA-2 Packetloader 1x10 Native tape capacity is 800gb. The only downside is, no magazine...it stores the tapes in an internal carosel accessed from the front, one position at a time. For a bit more $, they have magazine based tape library systems with VXA-2 drives. Anyone used these? I'd still like one. -- Jon Lewis | I route Senior Network Engineer | therefore you are Atlantic Net| _ http://www.lewis.org/~jlewis/pgp for PGP public key_ - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [OT] best tape backup system?
Guy wrote: I have NOT been able to share a SCSI cable/card with disks and a tape drive. Tried for days. I would get disk errors, or timeouts. I corrected the problem by putting the tape drive on a dedicated SCSI bus/card. I don't recall the details of the failures, since it has been well over a year now. But I do know I only had problems while using the tape drive and the disks at the same time. Like, during a backup. The disks were happy while the tape drive was idle. I also swapped parts, it had no effect. I assumed Linux does not like to share SCSI. There may be various reasons for this, and i think all of them are related to hardware only, esp. to the SCSI bus. Eg, some modern disk drives don't understand SE mode anymore, so can't be plugged into an scsi bus with at least one SE device. On the other hand, it was qutie common for esp. old tapes to NOT understand LVD mode. Obviously you can't mix that sort of devices on the same bus. I guess the bus where you drives are is in LVD mode while tapes works in SE mode... BTW, I've seen quite modern tape drive with an old scsi connector (I don't even remember anymore how it's called -- the one which looks pretty like an IDE connector but a bit wider and with more (80?) pins; with max speed of 20Mb/sec aka 10MHz or so) inside the case and with an adaptor for current 68pin scsi connector standard. Obviously it works in SE mode only (that bus worked in that mode only). Don't remember which vendor that drive was... /mjt - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [OT] best tape backup system?
In my case, I am sure I had the termination correct. I normally don't set the SCSI card to auto termination, since I don't trust it! But I did try every valid permutation. On non-Linux systems, I have never had problems mixing disks with tapes or anything else. And since I swapped terminators, cables and cards, the only hardware that could be at fault would be the tape or disk drives. But, they are still working to this day, just on separate SCSI cards. If I recall, I once had a Unix system where someone created about 128 Gig of sparse files. I backed up the files to a DDS-3 tape (12-24 Gig). The backup took more than 24 hours. That is better than 10 to 1. :) So, yes, giving the correct data, 2 to 1 can be done, but not in the real world. IMO. Guy -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gordon Henderson Sent: Tuesday, February 22, 2005 12:40 PM To: Guy Cc: linux-raid@vger.kernel.org Subject: RE: [OT] best tape backup system? On Tue, 22 Feb 2005, Guy wrote: > I have NOT been able to share a SCSI cable/card with disks and a tape > drive. Tried for days. I would get disk errors, or timeouts. I > corrected the problem by putting the tape drive on a dedicated SCSI > bus/card. I don't recall the details of the failures, since it has been > well over a year now. But I do know I only had problems while using the > tape drive and the disks at the same time. Like, during a backup. The > disks were happy while the tape drive was idle. I also swapped parts, > it had no effect. I assumed Linux does not like to share SCSI. Linux is fine with multiple devices on SCSI - scanners, drives, tapes. I haven't had problems with these combinations. The "usual culprit" is termination. Either not enough or too much! You need termination at both ends of the bus - one end is usually (but not always) the SCSI card, and all cards I've used in the past few years have had the ability to turn termination on or off (You turn it off if the card is not at one end of the bus) Some tape drives I've used also have the ability to turn termination on, or not - sometimes you set the drive number to one range for termination, another range for not (eg. 0-7 no termination, 8-15 active termination). It's a real PITA to get right at times. > I have not had problems with 2 or more tape drives on the same SCSI > bus/card. I think I had 3 at one time. > > Amanda... The last time I checked, incremental backups require a different > tape each time. You will need a lot of tapes. If a full backup fits on a > single tape, just do a full backup each night. I need many tapes to do a > full backup, but a single tape can hold many daily incremental backups. I > deemed Amanda to wasteful for me. I use home made scripts and cpio and do a > full backup about once per month, and do nightly incremental backups to 1 > tape. Once the daily tape is full I do another full backup. Works very > well for me. But, restoring is a pain, but that is very rare for me, only > once in 1+ years, so far. My scripts seek the tape as required, so I can > eject the tape if needed, as long as I put it back in time for the nightly > backup. Yup. One tape per backup run with Amanda. Way back when tape capacity exceeded disk capacity, I used Amanda to backup many machines to one tape every night - that was its original strength, the ability to backup many machines over the LAN to one tape drive. These days with disk capacities generally exceeding tapes, it's not like that anymore (although I still have some smaller servers backed up to a non-local tape drive for reasons of economy) > If anyone gets 1.3 to 1 compression, that is real good IMO. The > last time I checked, I got about 1.1 to 1. What a marketing scam Compression is always a weirdism - I'm guessing your data is music, video or pictures - stuff thats already compressed which won't compress twice. Typical "officy" type data would be stuff that generally compresses well - text documents, spreadsheets, program source code (& compiled binaries) etc. Amanda can compress data and in some cases better than the tape drives (using gzip, etc), but it's slow and makes restoring more interesting... I think Sony are claiming 2.3:1 with their new tapes - well, they'll get that with text-files, but nothing near that with anything else! Gordon - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [OT] best tape backup system?
On Tue, 22 Feb 2005, Guy wrote: > I have NOT been able to share a SCSI cable/card with disks and a tape > drive. Tried for days. I would get disk errors, or timeouts. I > corrected the problem by putting the tape drive on a dedicated SCSI > bus/card. I don't recall the details of the failures, since it has been > well over a year now. But I do know I only had problems while using the > tape drive and the disks at the same time. Like, during a backup. The > disks were happy while the tape drive was idle. I also swapped parts, > it had no effect. I assumed Linux does not like to share SCSI. Linux is fine with multiple devices on SCSI - scanners, drives, tapes. I haven't had problems with these combinations. The "usual culprit" is termination. Either not enough or too much! You need termination at both ends of the bus - one end is usually (but not always) the SCSI card, and all cards I've used in the past few years have had the ability to turn termination on or off (You turn it off if the card is not at one end of the bus) Some tape drives I've used also have the ability to turn termination on, or not - sometimes you set the drive number to one range for termination, another range for not (eg. 0-7 no termination, 8-15 active termination). It's a real PITA to get right at times. > I have not had problems with 2 or more tape drives on the same SCSI > bus/card. I think I had 3 at one time. > > Amanda... The last time I checked, incremental backups require a different > tape each time. You will need a lot of tapes. If a full backup fits on a > single tape, just do a full backup each night. I need many tapes to do a > full backup, but a single tape can hold many daily incremental backups. I > deemed Amanda to wasteful for me. I use home made scripts and cpio and do a > full backup about once per month, and do nightly incremental backups to 1 > tape. Once the daily tape is full I do another full backup. Works very > well for me. But, restoring is a pain, but that is very rare for me, only > once in 1+ years, so far. My scripts seek the tape as required, so I can > eject the tape if needed, as long as I put it back in time for the nightly > backup. Yup. One tape per backup run with Amanda. Way back when tape capacity exceeded disk capacity, I used Amanda to backup many machines to one tape every night - that was its original strength, the ability to backup many machines over the LAN to one tape drive. These days with disk capacities generally exceeding tapes, it's not like that anymore (although I still have some smaller servers backed up to a non-local tape drive for reasons of economy) > If anyone gets 1.3 to 1 compression, that is real good IMO. The > last time I checked, I got about 1.1 to 1. What a marketing scam Compression is always a weirdism - I'm guessing your data is music, video or pictures - stuff thats already compressed which won't compress twice. Typical "officy" type data would be stuff that generally compresses well - text documents, spreadsheets, program source code (& compiled binaries) etc. Amanda can compress data and in some cases better than the tape drives (using gzip, etc), but it's slow and makes restoring more interesting... I think Sony are claiming 2.3:1 with their new tapes - well, they'll get that with text-files, but nothing near that with anything else! Gordon - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [OT] best tape backup system?
I have NOT been able to share a SCSI cable/card with disks and a tape drive. Tried for days. I would get disk errors, or timeouts. I corrected the problem by putting the tape drive on a dedicated SCSI bus/card. I don't recall the details of the failures, since it has been well over a year now. But I do know I only had problems while using the tape drive and the disks at the same time. Like, during a backup. The disks were happy while the tape drive was idle. I also swapped parts, it had no effect. I assumed Linux does not like to share SCSI. I have not had problems with 2 or more tape drives on the same SCSI bus/card. I think I had 3 at one time. Amanda... The last time I checked, incremental backups require a different tape each time. You will need a lot of tapes. If a full backup fits on a single tape, just do a full backup each night. I need many tapes to do a full backup, but a single tape can hold many daily incremental backups. I deemed Amanda to wasteful for me. I use home made scripts and cpio and do a full backup about once per month, and do nightly incremental backups to 1 tape. Once the daily tape is full I do another full backup. Works very well for me. But, restoring is a pain, but that is very rare for me, only once in 1+ years, so far. My scripts seek the tape as required, so I can eject the tape if needed, as long as I put it back in time for the nightly backup. If anyone gets 1.3 to 1 compression, that is real good IMO. The last time I checked, I got about 1.1 to 1. What a marketing scam Guy -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gordon Henderson Sent: Tuesday, February 22, 2005 10:41 AM To: Louis-David Mitterrand Cc: linux-raid@vger.kernel.org Subject: Re: [OT] best tape backup system? On Tue, 22 Feb 2005, Louis-David Mitterrand wrote: > I am considering getting a Sony SAIT 3 with 500G/1TB tapes, which seems > like a nice solution for backuping a whole server on a single tape. I've been using DLT tapes for many years now, prior to that DAT tapes and Exabytes before that... Capacity is the one thing that you struggle with on tapes, and most of the servers I've built recently have had their disk partition sizes matched to the best DLT tape drive we could afford at the time. Your Sony tapes of 500GB (native, I presume and up to 1TB compressed) look quite attractive though, but I've no experience of how reliable they might be... Beware of the compression though - it all depends on what your data-set is - I can rarely get much beyond 1.3 times the native/raw capacity, but if all you are storing is text files you may well achieve close to 2x raw capacity. One thing I'd recomend is getting a seprate SCSI card just for the tape drive if possible, rather than daisy-chain it to the end of an existing SCSI bus with drives. You'll improve performance, and you'll also be able to hot remove/add the tape drive should you need to (assuming external drives) without the wory of upsetting a bus with disks passing live data. I'm moving towards external drives now to make it easier to replace the drive should it ever fail while maintaining server avalability. > Has anyone used that hardware and can comment on its performance, > linux-compatibility or otherwise? > > Is there a better solution out there? Things that I was looking for was long-term viability - (eg) what does the road-map look like for the Sony drives. Availability (and price!) of media, and so on, as well as things like being able to read older tapes on newer drives, should you get a bigger drive in the future. > Is it worth waiting a short while for some new upcoming technology? Personally, no. Strike while the iron is hot, Carpe Jugulum, and stuff like that! Get the best you can afford today, otherwise you'll always be chasing that next best thing thats just round the corner without actually implementing a solution. Other things to consider is the software you use to do the backup - I've been using Amanda for many (>12 ish) years with good results. It uses standard dump/xfsdump or tar as the underlying tape storage format, so even if you lose the Amanda database, you can still restore from the tapes, however, I have to admit that Amanda might not be the easiest thing to install for the first time and I've not actually looked for an alternative recently, so don't really have a handle on what else is out there, but you want something that will email you with the right 'next' tape to put in and email you the results, as well as something that will tell you what tape holds the latest versions of what files (especially if you ever get into the dreaded situation where you have to do incremental dumps) Amanda also checks that you have the right tape in before it overwrites it (it keeps a seaprate file at the start of the tape with the tape name) This is useful
Re: [OT] best tape backup system?
On Tue, 22 Feb 2005, Louis-David Mitterrand wrote: > I am considering getting a Sony SAIT 3 with 500G/1TB tapes, which seems > like a nice solution for backuping a whole server on a single tape. I've been using DLT tapes for many years now, prior to that DAT tapes and Exabytes before that... Capacity is the one thing that you struggle with on tapes, and most of the servers I've built recently have had their disk partition sizes matched to the best DLT tape drive we could afford at the time. Your Sony tapes of 500GB (native, I presume and up to 1TB compressed) look quite attractive though, but I've no experience of how reliable they might be... Beware of the compression though - it all depends on what your data-set is - I can rarely get much beyond 1.3 times the native/raw capacity, but if all you are storing is text files you may well achieve close to 2x raw capacity. One thing I'd recomend is getting a seprate SCSI card just for the tape drive if possible, rather than daisy-chain it to the end of an existing SCSI bus with drives. You'll improve performance, and you'll also be able to hot remove/add the tape drive should you need to (assuming external drives) without the wory of upsetting a bus with disks passing live data. I'm moving towards external drives now to make it easier to replace the drive should it ever fail while maintaining server avalability. > Has anyone used that hardware and can comment on its performance, > linux-compatibility or otherwise? > > Is there a better solution out there? Things that I was looking for was long-term viability - (eg) what does the road-map look like for the Sony drives. Availability (and price!) of media, and so on, as well as things like being able to read older tapes on newer drives, should you get a bigger drive in the future. > Is it worth waiting a short while for some new upcoming technology? Personally, no. Strike while the iron is hot, Carpe Jugulum, and stuff like that! Get the best you can afford today, otherwise you'll always be chasing that next best thing thats just round the corner without actually implementing a solution. Other things to consider is the software you use to do the backup - I've been using Amanda for many (>12 ish) years with good results. It uses standard dump/xfsdump or tar as the underlying tape storage format, so even if you lose the Amanda database, you can still restore from the tapes, however, I have to admit that Amanda might not be the easiest thing to install for the first time and I've not actually looked for an alternative recently, so don't really have a handle on what else is out there, but you want something that will email you with the right 'next' tape to put in and email you the results, as well as something that will tell you what tape holds the latest versions of what files (especially if you ever get into the dreaded situation where you have to do incremental dumps) Amanda also checks that you have the right tape in before it overwrites it (it keeps a seaprate file at the start of the tape with the tape name) This is useful when faced with a dozen tape drives and you are in a hurry... Tar (or star) might seem like a good way to dump a filesystem, but it's harder to extract a single file or directory off the tape unless you have a good index of everything thats on the tape. Restore has an interactive mode which lets you browse the index of the tape and add files and folders as needed before hitting the extract button and going away for several cups of coffee while it does its thing. There are potential problems with dump - there is a small but finite chance of data corruption when you dump (or even tar) a live filesystem, so I've been building servers with 2x the disk capacity and I rsync the live partition to the 'yesterday' partition, then remount that read-only and dump from that. So-far so good, and the punters get a instant restore if they accidentally delete a file. (Accidental file deletion is a PITA, taking sometimes many hours to restore from tape) Ah, found something relevant: http://dump.sourceforge.net/isdumpdeprecated.html That article is well-worth a read. Do check your restore mechanism, whatever method you use! Do deliberately remove (rename!) a file or directory and try to get it back from tape, so you are familiar with the mechanisms should you be called to do so for real. Restoring a entire partition is usually a lot easier than just a single file though, and don't forget to archive your root partition (if it's separate, so you can get back all your changes to the init files, etc. if you ever have to restore from scratch. Good luck, Gordon - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [OT] best tape backup system?
On Tue, 22 Feb 2005, Louis-David Mitterrand wrote: > Is there a better solution out there? We using an "59P6744 200/400GB LTO Full-High Tape Drive" with great resuslt. It made a full 180G backup within 100 minutes. We are using the "tob" script for full and differential backups. Bye, -=Lajbi= LAJBER Zoltan Szent Istvan Egyetem, Informatika Hivatal engineer: a mechanism for converting caffeine into designs. - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
