[Halld-offline] ENP consumption of disk space under /work
Chip Watson
watson at jlab.org
Fri Jun 9 10:57:09 EDT 2017
Mark et al,
Keep up! 5/31 and 6/1 were based upon a quick and dirty (and incorrect)
scan for disk usage, which mistakenly followed links, so your usage was
reported as being 4x of reasonable. The correct answer, learned later,
was that you were ONLY 2x of reasonable (coarse estimate). That
correction was the 6/7 data. On 6/8 you were presented a new option
(costing a bit more, which can be covered by sacrificing performance
(i.e. SSDs) in favor of space, (unless Graham can swing another few $K
or unless bids come in very favorable -- so I'm writing this in as best
value with the SSDs as an option which you may or may not be able to
afford). So now the 1.7 needed reduction is lessened by sacrificing
something else.
Yes, this is an iterative, collaborative process, played out at high
speed! (anyone else dizzy?)
It still remains true that you have to trim your work from your
(GlueX's) most recently reported (6/7) 59 TB down 25% to reach the
target of 44 TB. I.e. down by a factor of 1.34 instead of 1.7, and
perhaps you are already converging on this. You'll have a month to get
down to that point, so no rush -- 5% a week should do it. But remember,
it remains possible for you to balloon up again, so watch your diet!
Lightly spoken,
Chip
On 6/8/17 4:49 PM, Mark Ito wrote:
>
> Chip,
>
> Indeed we do have to choose! You are quite right. Here are my notes
> and conclusion.
>
> On 5/31 the choices were:
>
> (1) Physics cuts its use of /work by a factor of 4-5.
> (2) Physics increases funding to $40K
> (3) We pull a server out of Lustre, decreasing Physics' share of the
> system, and use that as half of the new active-active pair, beefing it
> up with SSDs and perhaps additional memory; this would actually shrink
> Physics near term costs, but puts higher pressure on the file system for
> the farm
>
> On 6/1:
>
> Option 3: shrink /work 2x (to 172 TB), freeze cache & volatile, ~$5K
> (performance hit on the farm)
> new system has 2 JBODS, 2 controllers per head
> might need to temporarily shrink space by 190 TB
> on top of the 2x to drain a node to re-purpose it
> if LQCD needs its disk space back
>
> Option 1: shrink /work 4x and increase cache and volatile by 25%
> ~$15K
> (Chip's recommendation)
> new system has 1 JBOD and can be expanded in the future
>
> Option 2: /work as is (340 TB), increase cache & volatile by 25%,
> ~$40K
> (over budget)
> needs 3 JBODs for the new system, 2 cascaded for ENP
>
> and also on 6/1:
> We have NO intention of keeping /work on Lustre.
>
> On 6/7:
>
> So, in the absence of money (which clearly seems to be the case),
> do you choose (a) reduce your use of work by 1.7x, or (b) reduce
> your use of cache + volatile by 25%. There is no middle case.
>
> And today, 6/8:
>
> I'll offer one more option: we can use 10TB drives instead of
> 8TB.
>
> and also today:
>
> Default choice if no one else votes is now this: new /work server
> is procured with 44 drives, 10 TB HGST He10 enterprise drives (top
> rated, new big brother to our He8 drives).
>
> So I am confused....
>
> ...but I think I like this last default choice. Let's see if I
> understand it:
>
> a) /work _not_ on Lustre
>
> b) 44 TB total /work for Hall D
>
> c) Hall D /cache and /volatile about the same as now or they grow a bit
>
> d) we can afford this with this year's money
>
> If I have that right[?!], then the default is fine. SSD's would be
> nice of course, but I don't think they are critical since we are
> compute bound. The big advance for us would be a more reliable work
> disk at the cost of slightly less of it.
>
> And don't get me wrong, I do appreciate the effort in coming up with a
> solution. :-)
>
> -- Mark
>
> On 06/08/2017 11:42 AM, Chip Watson wrote:
>>
>> Mark,
>>
>> Sorry, you don't get off that easy :P. You have to choose, and not
>> choosing means you choose what follows.
>>
>> I'll offer one more option: we can use 10TB drives instead of 8TB.
>> Probably slightly longer rebuild times, but actually higher streaming
>> bandwidth. Cost will go up, maybe a few $K. I think we can find a
>> way to squeeze that out of the system.
>>
>> Default choice if no one else votes is now this: new /work server is
>> procured with 44 drives, 10 TB HGST He10 enterprise drives (top
>> rated, new big brother to our He8 drives). If Physics is poor, we
>> can defer buying them the read cache SSD to compensate for the higher
>> price of 10TB (Graham, can you swing an extra $3K?).
>>
>> 21 drives for ENP, 21 for LQCD, 2 hot spares in a 44 drive
>> enclosure (SSDs in hosts)
>>
>> ENP and LQCD each get total quota (enforced) of 108 TB
>>
>> GlueX, CLAS-12 each get 44 TB, A and C get 10 TB (enforced)
>>
>> CLAS-12 says they can live within this, and C believes they are
>> already there. GlueX and A will need to figure out what can be moved
>> into /volatile.
>>
>> If requested, we can give you modest lifetime "pin" for /volatile so
>> some large data files that should not go to tape can have longer
>> lifetimes in Lustre /volatile than they can today.
>>
>> Next year, for about $10K we can add a second cascaded JBOD next year
>> with one more RAID stripe for ENP. We'll also need to spend $25K to
>> replace the Lustre storage that ages out in FY18 (or suffer the
>> reduction).
>>
>> regards,
>>
>> Chip
>>
>>
>> On 6/8/17 9:40 AM, Mark Ito wrote:
>>>
>>> That was just an observation. I would not interpret it as a vote for
>>> anything... :-)
>>>
>>>
>>> On 06/08/2017 09:33 AM, Chip Watson wrote:
>>>>
>>>> I'll take this as a vote by GlueX to have more work and reduce cache.
>>>>
>>>> Do A,B,C concur?
>>>>
>>>>
>>>> On 6/8/17 9:28 AM, Mark Ito wrote:
>>>>>
>>>>> In my previous estimate, of the cache portion, 278 TB, only 105 TB
>>>>> of that is pinned. The unpinned part is presumeably old files that
>>>>> should be gone, but have not been deleted since there happens to
>>>>> be no demand for the space. If we use 105 TB as our cache usage
>>>>> then re-doing your estimate gives 555 TB, which means in 9 months
>>>>> we will have 270 TB of unused space. Which would mean that we have
>>>>> room to increase our usage without buying anything!
>>>>>
>>>>>
>>>>> On 06/07/2017 05:54 PM, Chip Watson wrote:
>>>>>>
>>>>>> Mark,
>>>>>>
>>>>>> I still need you to answer the question of how to further reduce
>>>>>> usage and how to configure. Your usage as you report it is about
>>>>>> 370 TB. Assuming that Hall B needs the same within 9 months, and
>>>>>> that A+C need half as much, then that leads to a total of 925TB
>>>>>> which is more than Physics owns, by 100 TB (NOT CURRENT USAGE,
>>>>>> JUST PROJECTION BASED ON GLUEX USAGE).
>>>>>>
>>>>>> There is also the question of how to split the storage budget.
>>>>>> In budget, you can have new half a JBOD: 21 disks configured as 3
>>>>>> RAID z2 stripes of 5+2 disks, 8TB, thus 120 raw data, 108 in a
>>>>>> file system, and 86 TB at 80% -- for all of GlueX, CLAS-12, A and
>>>>>> C. If GlueX is 40% of the total, that makes 35TB, and you are
>>>>>> still high by 70%.
>>>>>>
>>>>>> The other low cost option is to re-purpose a 2016 Lustre node so
>>>>>> that /work is twice this size (one full JBOD), and GlueX can use
>>>>>> 70TB as /work. But then you must reduce /cache + /volatile by a
>>>>>> comparable amount since we have to pull a node out of
>>>>>> production. And this still isn't free since we'll need a total
>>>>>> of 4 RAID cards instead of 2 to provide correct performance, and
>>>>>> we'll need to add SSD's to the mix.
>>>>>>
>>>>>> So, in the absence of money (which clearly seems to be the case),
>>>>>> do you choose (a) reduce your use of work by 1.7x, or (b) reduce
>>>>>> your use of cache + volatile by 25%. There is no middle case.
>>>>>>
>>>>>> thanks,
>>>>>>
>>>>>> Chip
>>>>>>
>>>>>>
>>>>>> On 6/7/17 5:30 PM, Mark Ito wrote:
>>>>>>>
>>>>>>> Summarizing Hall D work disk usage (/work/halld only):
>>>>>>>
>>>>>>> o using du, today 2017-06-06, 59 TB
>>>>>>>
>>>>>>> o from our disk-management database, a couple of days ago,
>>>>>>> 2017-06-04, 86 TB
>>>>>>>
>>>>>>> I also know that one of our students got rid of about 20 TB of
>>>>>>> unneeded files yesterday. That accounts for part of the drop.
>>>>>>>
>>>>>>> We produce a report from that database
>>>>>>> <https://halldweb.jlab.org/disk_management/work_report.html>
>>>>>>> that is updated every few days.
>>>>>>>
>>>>>>> From the SciComp pages, Hall D is using 287 TB on cache and 21
>>>>>>> TB on volatile.
>>>>>>>
>>>>>>> My view is that this level of work disk usage is more or less as
>>>>>>> expected, consistent with our previous estimates, and not
>>>>>>> particularly abusive. That having been said, I am sure there is
>>>>>>> a lot that can be cleaned up. But as Ole pointed out, disk usage
>>>>>>> grows naturally and we were not aware that this was a problem. I
>>>>>>> seem to recall that we agreed to respond to emails that would be
>>>>>>> sent when we reached 90% of too much, no? Was the email sent out?
>>>>>>>
>>>>>>> One mystery: when I ask Lustre what we are using I get:
>>>>>>>
>>>>>>> ifarm1402:marki:marki> lfs quota -gh halld /lustre
>>>>>>> Disk quotas for group halld (gid 267):
>>>>>>> Filesystem used quota limit grace files quota limit grace
>>>>>>> /lustre 290T 470T 500T - 15106047 0 0 -
>>>>>>> which is less than cache + volatile, not to mention work. I
>>>>>>> thought that to a good approximation this 290 TB should be the
>>>>>>> sum of all three. What am I missing?
>>>>>>>
>>>>>>> On 05/31/2017 10:35 AM, Chip Watson wrote:
>>>>>>>> All,
>>>>>>>>
>>>>>>>> As I have started on the procurement of the new /work file
>>>>>>>> server, I have discovered that Physics' use of /work has grown
>>>>>>>> unrestrained over the last year or two.
>>>>>>>>
>>>>>>>> "Unrestrained" because there is no way under Lustre to restrain
>>>>>>>> it except via a very unfriendly Lustre quota system. As we
>>>>>>>> leave some quota headroom to accommodate large swings in usage
>>>>>>>> for each hall for cache and volatile, then /work continues to
>>>>>>>> grow.
>>>>>>>>
>>>>>>>> Total /work has now reached 260 TB, several times larger than I
>>>>>>>> was anticipating. This constitutes more than 25% of Physics'
>>>>>>>> share of Lustre, compared to LQCD which uses less than 5% of
>>>>>>>> its disk space on the un-managed /work.
>>>>>>>>
>>>>>>>> It would cost Physics an extra $25K (total $35K - $40K) to
>>>>>>>> treat the 260 TB as a requirement.
>>>>>>>>
>>>>>>>> There are 3 paths forward:
>>>>>>>>
>>>>>>>> (1) Physics cuts its use of /work by a factor of 4-5.
>>>>>>>> (2) Physics increases funding to $40K
>>>>>>>> (3) We pull a server out of Lustre, decreasing Physics' share
>>>>>>>> of the system, and use that as half of the new active-active
>>>>>>>> pair, beefing it up with SSDs and perhaps additional memory;
>>>>>>>> this would actually shrink Physics near term costs, but puts
>>>>>>>> higher pressure on the file system for the farm
>>>>>>>>
>>>>>>>> The decision is clearly Physics', but I do need a VERY FAST
>>>>>>>> response to this question, as I need to move quickly now for
>>>>>>>> LQCD's needs.
>>>>>>>>
>>>>>>>> Hall D + GlueX, 96 TB
>>>>>>>> CLAS + CLAS12, 98 TB
>>>>>>>> Hall C, 35 TB
>>>>>>>> Hall A <unknown, still scanning>
>>>>>>>>
>>>>>>>> Email, call (x7101), or drop by today 1:30-3:00 p.m. for
>>>>>>>> discussion.
>>>>>>>>
>>>>>>>> thanks,
>>>>>>>> Chip
>>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Mark Ito,marki at jlab.org, (757)269-5295
>>>>>>
>>>>>
>>>>> --
>>>>> Mark Ito,marki at jlab.org, (757)269-5295
>>>>
>>>
>>> --
>>> Mark Ito,marki at jlab.org, (757)269-5295
>>
>
> --
> Mark Ito,marki at jlab.org, (757)269-5295
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