btape getting 89 MBs, so maybe my disk and sql updating is effecting
the speed? note drive has a 16384 blocksize, ran tapeinfo on the
drive...gary

[root@genepi1 bacula]# btape -c /etc/bacula/bacula-sd.conf /dev/nst0
Tape block granularity is 1024 bytes.
btape: butil.c:284 Using device: "/dev/nst0" for writing.
01-Dec 12:29 btape JobId 0: 3301 Issuing autochanger "loaded? drive 0" command.
01-Dec 12:29 btape JobId 0: 3302 Autochanger "loaded? drive 0", result
is Slot 12.
btape: btape.c:476 open device "LTO-4" (/dev/nst0): OK
*speed file_size=3 skip_raw
btape: btape.c:1082 Test with zero data and bacula block structure.
btape: btape.c:960 Begin writing 3 files of 3.221 GB with blocks of
2097152 bytes.
+++4
btape: btape.c:608 Wrote 1 EOF to "LTO-4" (/dev/nst0)
btape: btape.c:410 Volume bytes=3.221 GB. Write rate = 89.47 MB/s
+++
btape: btape.c:608 Wrote 1 EOF to "LTO-4" (/dev/nst0)
btape: btape.c:410 Volume bytes=3.221 GB. Write rate = 89.47 MB/s
+++
btape: btape.c:608 Wrote 1 EOF to "LTO-4" (/dev/nst0)
btape: btape.c:410 Volume bytes=3.221 GB. Write rate = 89.47 MB/s
btape: btape.c:384 Total Volume bytes=9.663 GB. Total Write rate = 89.47 MB/s

btape: btape.c:1094 Test with random data, should give the minimum throughput.
btape: btape.c:960 Begin writing 3 files of 3.221 GB with blocks of
2097152 bytes.
+++
btape: btape.c:608 Wrote 1 EOF to "LTO-4" (/dev/nst0)
btape: btape.c:410 Volume bytes=3.221 GB. Write rate = 16.02 MB/s
+++
btape: btape.c:608 Wrote 1 EOF to "LTO-4" (/dev/nst0)
btape: btape.c:410 Volume bytes=3.221 GB. Write rate = 33.90 MB/s
+++
btape: btape.c:608 Wrote 1 EOF to "LTO-4" (/dev/nst0)
btape: btape.c:410 Volume bytes=3.221 GB. Write rate = 44.12 MB/s
btape: btape.c:384 Total Volume bytes=9.663 GB. Total Write rate = 26.18 MB/s


[root@genepi1 bacula]# tapeinfo
Usage: tapeinfo -f <generic-device>
[root@genepi1 bacula]# tapeinfo -f /dev/changer
Product Type: Medium Changer
Vendor ID: 'OVERLAND'
Product ID: 'NEO Series      '
Revision: '0504'
Attached Changer API: No
SerialNumber: '2B81000045'
SCSI ID: 1
SCSI LUN: 1
Ready: yes
[root@genepi1 bacula]# tapeinfo -f /dev/nst0
Product Type: Tape Drive
Vendor ID: 'HP      '
Product ID: 'Ultrium 4-SCSI  '
Revision: 'B12H'
Attached Changer API: No
SerialNumber: 'HU17450M8L'
MinBlock: 1
MaxBlock: 16777215
SCSI ID: 1
SCSI LUN: 0
Ready: yes
BufferedMode: yes
Medium Type: Not Loaded
Density Code: 0x46
BlockSize: 16384
DataCompEnabled: yes
DataCompCapable: yes
DataDeCompEnabled: yes
CompType: 0x1
DeCompType: 0x1
BOP: yes
Block Position: 0
Partition 0 Remaining Kbytes: 799204
Partition 0 Size in Kbytes: 799204
ActivePartition: 0
EarlyWarningSize: 0
NumPartitions: 0
MaxPartitions: 0



On Thu, Dec 1, 2011 at 10:49 AM,  <mark.bergman AT uphs.upenn DOT edu> wrote:
> In the message dated: Thu, 01 Dec 2011 16:27:33 GMT,
> The pithy ruminations from Alan Brown on
> <Re: [Bacula-users] tuning lto-4> were:
> => gary artim wrote:
> => > You guys/gals are great, very responsive! I did try
> => > spooling/despooling and my run times shot up.
> =>
> => They will - you're copying everything twice (disk to disk to tape), but
> => this is the only way to achieve fast despooling speeds - if you don't do
> => this then your LTO drive will start to "shoe shine" and speeds drop off
> => rapidly when it happens.
>
> And you increase wear & tear on the drive and media.
>
> =>
> => The trick is to run multiple jobs at once - you have to spool to achieve
> => this anyway or extracting will be a nightmare.
> =>
> => Spooling is a net gain when you're running incrementals.
> =>
>
> Not necessarily. Spooling is a gain if you are measuring the speed
> of writing to tape. Spooling may be a net loss for end-to-end (client
> machine-->spool server-->tape drive) speed.
>
> For backups clients where the total volume being backed up is less than
> the spool size, then there's a very good chance of a performance gain. As
> soon as a job requires multiple rounds of spooling and de-spooling,
> there's a good chance of a performance loss because bacula stops reading
> from the client machine (stops spooling that job) as soon as despooling
> begins. Of course, spooling allows you to run multiple jobs in parallel, a
> clear win over running them in series.
>
>
> See:
>
>        [1] http://copilotco.com/mail-archives/bacula-devel.2007/msg02642.html
>        [2] 
> http://www.bacula.org/git/cgit.cgi/bacula/plain/bacula/projects?h=Branch-5.1
>
>        [3] http://www.mail-archive.com/bacula-users AT lists.sourceforge DOT 
> net/msg49366.html
>
>
> => Spooling MUST happen on a fast dedicated drive. You're best off dropping
> => in a fast SSD such as a 64/128Gb OCZ vertex3 or similar to handle it.
>
> Hmm...for LTO4 (large spool files are good), you might want more space
> than that, particularly if you have multiple clients (multiple spool
> files). A more cost-effective option might be several fast drives (10K
> or 15K SAS or SCSI) in RAID-0. It doesn't take very many drives in RAID0 to
> have an aggregate drive throughput that is greater than the bus interface.
>
> =>
> => > I was using a simple
> => > 7200 drive though, no ssd or raid...I assume the performance gain
>
> Yeah, the sustained read speed from a 7.2k RPM drive is lower than the
> possible write speed to an LTO-4 drive:
>
>       
>  http://www.seagate.com/www/en-us/support/before_you_buy/speed_considerations
>
> => > happens when your networks multi machines...wearing multiple hats so
> => > will report back on btape next week, unless I get some time. gary
> =>
> => Even on a single host, if the heads are thrashing then spooling will
> => save time overall. The big advantage is being able to run multiple jobs
> => so that several are spooling data at the same time one is despooling.
>
> Absolutely. Spooling is a big win for multiple jobs, and for reducing
> wear&tear on the tape drive. It may or may not give a performance increase for
> any single backup job.
>
> Mark
>
>

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