certance DAT

[.VWV.]

[Technicians' or hackers' suggestions seem like music to me. Thanks. I
am compelled on this shit system, owing to the need of managing some
commercial stuff. I hate it. Please forgive me for using it].

I have compared some features among different current tape drive
standards. It seems DLT and LTO Ultrium 2 cartridges are more expensive
then DAT 72 and VXA 2 ones. I have not found yet a criterion useful to
choose the most reliable standard. Any suggestion could be useful. I'll
need either to dump or to tar.

Please CC me. Thanks once more.

.VWV.

---- Original Message ----
From: "Glenn Dawson" <glenn at antimatter.net>
To: "Chuck Swiger" <cswiger at mac.com>; ".VWV."
<victorvittorivonwiktow at interfree.it> Cc:
<freebsd-questions at freebsd.org> Sent: Wednesday, 27 July, 2005 05:19
Subject: Re: certance DAT

> At 08:17 PM 7/26/2005, Chuck Swiger wrote:
> ...so it's not exactly super-zippy, either.  Hmm, is it just me, or
> are the following numbers significantly low for a RAID-1 of two 10K
> RPM U320 SCSI disks...?
>
>> /dev/amrd1
>>         512             # sectorsize
>>         73274490880     # mediasize in bytes (68G)
>>         143114240       # mediasize in sectors
>>         8908            # Cylinders according to firmware.
>>         255             # Heads according to firmware.
>>         63              # Sectors according to firmware.
>>
>> Seek times:
>>         Full stroke:      250 iter in   1.824059 sec =    7.296 msec
>>         Half stroke:      250 iter in   1.805398 sec =    7.222 msec
>>         Quarter stroke:   500 iter in   4.254147 sec =    8.508 msec
>>         Short forward:    400 iter in   2.821081 sec =    7.053 msec
>>         Short backward:   400 iter in   2.860203 sec =    7.151 msec
>>         Seq outer:       2048 iter in   8.821875 sec =    4.308 msec
>>         Seq inner:       2048 iter in   9.006505 sec =    4.398 msec
>> Transfer rates:
>>         outside:       102400 kbytes in   9.242111 sec =    11080
>>         kbytes/sec middle:        102400 kbytes in   9.230325 sec =
>>         11094 kbytes/sec inside:        102400 kbytes in  10.779231
>> sec =     9500 kbytes/sec
>>
>> [ This is running RELENG_5_4... ]
>
> I would have expected the transfer rates to be about twice what
> they're listed as here.  Though I don't know how you measured them.
>
> If you want to see something interesting, create a ufs1 file system
> on the same raid 1 using FreeBSD 4.x.  Then mount it in 5.x and do
> your test for transfer rates.  Compare that to either ufs1 or ufs2 on
> the same raid 1 as created by 5.4.
>
> The results are very interesting.
>
> -Glenn
>
>
>> --
>> -Chuck