One issue that comes up repeatedly is the requirements of a server and the holding disk
configuration to keep an LTO6 (or LTO5) streaming at something approaching its rated speed, which is
faster than that of an individual disk drive.
The most common approach is to have an array of high speed disk drives configured in raid10 or raid5
for holding space to get data transfer speeds high enough.
We are trying to set up a new server and a new tape library without breaking the budget, and we need
a lot of external storage just for storage, even without the question of Amanda and a holding disk.
We have a J4500 hanging off our T5220 and hope to carry it over to a new Supermicro server. We
planned on filling the internal bays on the Supermicro and using software raid to configure them.
We'll be using Ubuntu LTS, I'm guessing 14.04, since this project will be for the summer.
Kicking ideas around for speed, throughput, etc. to drive the LTO, we came up with the idea of just
getting a pair of SSDs for holding disk space. Those ought to be individually faster than the LTO by
a good bit.
Has anyone done this? Any comments?
This also lead us to the question/idea of whether Amanda could be configured with some sort of
"staged" holding disk. In other words, suppose you had some multi-TB disk drives for holding disk,
and a couple of SSDs for transfer to tape. Backups would go to the first stage disk drives. When
they were complete, they would be transferred to the SSDs. The tape would be written from backups
that are complete and on the SSDs. If the tape were out of order or offline, then the disk drives
would provide some capacity for holding incrementals for a while, whereas if our holding disks were
just SSDs, then our fall back capacity would be substantially smaller.
Thoughts?
Might there be a way within Ubuntu of configuring a disk drive with an ssd for read/write cache that
would achieve what we are after? ZFS does something a bit like this, though not exactly.
--
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Chris Hoogendyk
-
O__ ---- Systems Administrator
c/ /'_ --- Biology & Geology Departments
(*) \(*) -- 347 Morrill Science Center
~~~~~~~~~~ - University of Massachusetts, Amherst
<hoogen...@bio.umass.edu>
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Erdös 4
