Quantum SDLT 320 & AHA 2940UW Configuration Help Please

[Folkert Rienstra]

It is part of the equation.

The tape drive can only work as fast as the data can come in.

Which has been said now how many times?

The data can come in only as fast as the disks can be read from,

Which wildly differs with how data is backed up, using the file system
(file backup) or without using the file system (image backup) using direct
IO, simply sequentially backing up all the sectors of a partition or physical
harddrive. Or alternatively, the backing up of an image saved as a single file.

File backup is very random data access. Random read of sectors
on a harddrive can be 10 times as slow as for sequential access.
Which means that a drive has to be 10 times as fast (STR) as the
tapedrive at 13MB/s. Even if his drives are fairly recent and can do
say 50 to 60MB/s they will come short. If not at the beginning of the
drive, certainly when nearing the end where it will only do 30 or so.

and everything in between.


If you can give a model number this would help since there are different
generations of 40 GB drives which have different performance.

None will be that fast that they can deliver random data at 13MB/s.

 

[Folkert Rienstra]

Folkert,

I am terribly sorry

No you don't. You would shape-up considerably if you did. No signs of that.

if I have offended you with my

lack of knowledge about this topic

Hasn't got anything to do with that.

or posting in this group.

Or that either.

Just has to do with your blatant disregard of advice when given
and your urgent need to rant without giving requested information.
You can say a 100 times how much you appreciate our advice but
your actions show you a blatant liar. You apologize for not giving
the requested info and then go on by not giving the requested info.
Yet another post from you and still haven't given that information.

No, you don't draw blood at all. You are quite helpful.

It never occurred to me that the actual drive type would have any
bearing on the tape doing this "shoe-shining".

It doesn't. Nobody said anything about drive type.
The exact question was:
"The big unanswered question right now is what drives are you backing up?"

I can tell you that I have tried to backup the various IDE drives
(Seagate & IBM / 40Gb ~ 9 ms ) in my system, all with the same result.

And still not the requested info, just more of your ranting.

Although I appreciate your assistance,

No you don't, Liar Troll.

I find it quite rude of you to chastise me in this way.

Almost as rude as asking for information and then completely
disregarding everything that is handed to you?
Refusing requests for more info even after multiple requests.
Yes, I'd say that that is very rude.

I can assure you that I am not doing this
to "draw blood" oar anything of the sort.

Yet you manage perfectly.
Which is obviously why you made it a point of *topposting* this in clearly
the wrong post. It all just comes very natural to you, doesn't it, Troll.

I simply am looking for information from people who know more about
this than I do.

Yup, and go ignoring everything that is provided to you and ask new stupid
questions which show how you disregarded what was handed to you earlier.

You are not looking for information. You wouldn't recognize information
if it bit you in the arse. If you appreciated information you would follow
up on it and provide the additionally requested info with as much precision
as possible. Sofar you have never done that. Only more of your rants.

If you have no patience for new users such as myself, please have the
fortitude to ignore this thread.

No such luck.

 

[Steve Cousins]

Which wildly differs with how data is backed up, using the file system
(file backup) or without using the file system (image backup) using direct
IO, simply sequentially backing up all the sectors of a partition or physical
harddrive. Or alternatively, the backing up of an image saved as a single file.

This is true. I don't know how Windows Backup works but I'm guessing it
is doing "file backup". Definitely doing an image backup should be
quite a bit faster.

File backup is very random data access. Random read of sectors
on a harddrive can be 10 times as slow as for sequential access.
Which means that a drive has to be 10 times as fast (STR) as the
tapedrive at 13MB/s. Even if his drives are fairly recent and can do
say 50 to 60MB/s they will come short. If not at the beginning of the
drive, certainly when nearing the end where it will only do 30 or so.

I guess I have been lucky. I have some older systems that have
relatively slow disk systems that I've been able to stream to our
SDLT220 drive which has a native speed of 11MB/s. Even with hardware
compression on (which is about 1.4:1 with our data, and hence needing
about 15.4 MB/s) I've been able to stream to it using tar to do file
backups. They are SCSI drives but from 5 years ago, like the Barracuda
37, 73 and 181 drives. I guess DDRA has helped out with this because I
think these are around 10MB/s. Oh yeah, and we also had a Dell PERC 2
RAID system that was terrible for performance. Something like 4MB/sec
RAID5 writes and 7MB/sec reads. I do remember having trouble doing
backups with this. Ended up staging it to a series of 2GB files on one
of the 181 GB drives.

 

[Folkert Rienstra]

This is true.
I don't know how Windows Backup works but I'm guessing it is doing "file
backup". Definitely doing an image backup should be quite a bit faster.


I guess I have been lucky. I have some older systems that have
relatively slow disk systems that I've been able to stream to our
SDLT220 drive which has a native speed of 11MB/s.
Even with hardware compression on (which is about 1.4:1 with our
data, and hence needing about 15.4 MB/s)

I've been able to stream to it using tar to do file backups.

So this sounds like backing up an Image file (in this case an Archive).
Does this write directly to tape 'on the go' or does it buffer to a tempo-
rary file (on disk or in memory) and is it written from there? If the lat-
ter, then this could extend that drive's buffer from 32MB to much larger
and keep the drive streaming for far longer than the 3 seconds that it's
own buffer can provide, provided that that buffer fills up and empties
totally each time. It may shoeshine but with less and much longer strokes.

They are SCSI drives but from 5 years ago, like the Barracuda 37, 73
and 181 drives. I guess DDRA has helped out with this because I think
these are around 10MB/s.

STR according to stats that I can find:
Barracuda 180 (-7 series) can do 41-22 MB/s.
Barracuda 36 (-5 series) 19-11 MB/s.
Barracuda 36ES (-8 series) 39-29 MB/s.

Can't find Barra73. Cheetah 73 did 34-19 MB/s.

 

[Steve Cousins]

So this sounds like backing up an Image file (in this case an Archive).
Does this write directly to tape 'on the go' or does it buffer to a tempo-
rary file (on disk or in memory) and is it written from there? If the lat-
ter, then this could extend that drive's buffer from 32MB to much larger
and keep the drive streaming for far longer than the 3 seconds that it's
own buffer can provide, provided that that buffer fills up and empties
totally each time. It may shoeshine but with less and much longer strokes.

These are completely "on the go" except for the ones I staged from the
very slow PERC RAID. For instance:

tar cvbf 1024 /dev/tape /usr3

where usr3 is a mounted partition (the whole drive) from one of the 181
GB drives. It contains files anywhere from ~0 bytes to around 85 MB. The
vast majority of the data is in the larger files of course but there are
probably about as many small files as there are "large" files.

STR according to stats that I can find:
Barracuda 180 (-7 series) can do 41-22 MB/s.
Barracuda 36 (-5 series) 19-11 MB/s.
Barracuda 36ES (-8 series) 39-29 MB/s.

Can't find Barra73. Cheetah 73 did 34-19 MB/s.

Wow! Both on your encyclopedic knowledge (or extreme desire to Google)
and on the numbers. They seem high to me but it has been a while since
I've had to do much with those disks. They do what I need and the
performance isn't a problem for what they are doing (storing older ocean
model programs and data) that I haven't needed to deal with them. They
just keep on working.

I think you are right, the 73's are Cheetah's. We also have a couple of
Cheetah 146's too.

 

[Mike Tomlinson]

Can't find Barra73. Cheetah 73 did 34-19 MB/s.

Cheetah 73s were good drives in their day, but full height and ran very
hot.

 

[Folkert Rienstra]

These are completely "on the go" except for the ones I staged from the
very slow PERC RAID. For instance:

tar cvbf 1024 /dev/tape /usr3

where usr3 is a mounted partition (the whole drive) from one of the 181
GB drives. It contains files anywhere from ~0 bytes to around 85 MB.
The vast majority of the data is in the larger files of course but there
are probably about as many small files as there are "large" files.

Wow! Both on your encyclopedic knowledge (or extreme desire to Google)

Nah, not really, just picked from a hardcopy list of benchresults as published on-
ce in a while by the german PC mag c't that I always keep around for comparison.

and on the numbers.

5 years is not that old.

They seem high to me but it has been a while since I've had to do much
with those disks.

Well, they are STRs.

 

[Steve Cousins]

Cheetah 73s were good drives in their day, but full height and ran very
hot.

Half-height. I haven't run into a full height drive in quite a while
(15 years) and that was a 5.25" drive. I think it was a Micropolis ESDI
drive in the 330 MB range, which was absolutely huge to us.

 

[Mike Tomlinson]

Half-height. I haven't run into a full height drive in quite a while
(15 years) and that was a 5.25" drive.

Take a look at ST173404LW.

 

[Folkert Rienstra]

So did a barracuda I once had. Your average 1" height model, one
of those sealed with black selfadhesive plastic on top of the lid.
Got so stinking hotyou could nearly touch it.

Half-height.

Time for Mike to retire. He can't get anything right anymore.

 

[Folkert Rienstra]

Take a look at ST173404LW.

Yes, now what? Where exactly does it say full height?

1.6" is half height. Did someone step on your head, Tomlinson?

 

[Mike Tomlinson]

1.6" is half height. Did someone step on your head, Tomlinson?

You really should ask your doctor for some Prozac, Folkert. It might
cheer you up a bit.

 

[Folkert Rienstra]

You really should ask your doctor for some Prozac, Folkert.

Is that what you're using Tomlinson.

It might cheer you up a bit.

And cause the same mush that is in your head? No thanks.